Multi-Channel DMA Controller IP User's Guide
Contents
1. ORCA 4 sysMEM Mode Name of Parameter File LUTs PFUs Registers EBRs YO fmax MHz 8237 dma_mc_04_2_001 Ipc 1258 200 524 N A 59 58 Non 8237 dma_mc_04_2_002 lpc 2661 499 1187 N A 125 66 1 Performance and utilization characteristics are generated using OR4E02 2PBGAM680 DE in Lattice s ispLEVER 3 0 SP1 software Syn thesized using Synplicity Synplify 7 03 When using this IP core in a different density package speed or grade within the ORCA family performance may vary 2 PFUisa standard logic block of some Lattice devices For more information check the data sheet of the device Supplied Netlist Configurations The Ordering Part Number OPN for all configurations of this core in ORCA Series 4 devices is DMA MC 04 N2 Table 19 lists the Lattice specific netlists that are available in the Evaluation Package which can be downloaded from the Lattice web site at www latticesemi com Table 19 Core Configuration Paramotor Fili Number of Channels Data Bus Width Address Bus Width Word Count Width 8237 Mode dma_mc_04_2_001 lpc 4 8 16 16 Non 8237 Mode dma_mc_04_2_002 lpc 4 32 32 16 24 Lattice Semiconductor Appendix for ispXPGA FPGAs Table 20 Performance and Resource Utilization Multi Channel DMA Controller User s Guide Name of ispXPGA sysMEM Mode Parameter File LUT4 PFUs Registers EBRs 1 0 fmax MHz 8237 dma_mc_xp_2_0012. 26 Lattice Semiconductor Appendix for LatticeXP FPGAs Table 24 Performance and Resource Utilization Multi Channel DMA Controller User s Guide Name of sysMEM Mode Parameter File SLICEs LUTs EBRs Registers 1 0 fmax MHz 8237 dma_mc_xm_3_001 lpc 746 1287 0 555 59 71 Non 8237 dma_mc_xm_3_002 Ipc 1794 3084 0 1179 125 80 1 Performance and utilization characteristics are generated using LFXP10E 4F388C in Lattice ispLEVER 5 0 software When using this IP core in a different density package or speed grade performance may vary Supplied Netlist Configurations The Ordering Part Number OPN for all configurations of this core in LatticeXP devices is DMA MC XM N3 Table 25 lists the Lattice specific netlists that are available in the Evaluation Package which can be downloaded from the Lattice web site at www latticesemi com Table 25 Core Configuration i Number of Channels Data Bus Width Address Bus Width Word Count Width 8237 Mode dma_mc_xm_3_001 lpc 4 8 16 16 Non 8237 Mode dma_me_xm_3_002 lpc 4 32 32 16 You can use the IPexpress software tool to help generate new configurations of this IP core IPexpress is the Lattice IP configuration utility and is included as a standard feature of the ispLEVER design tools Details regarding the usage of IPexpress can be found in the IPexpress and ispLEVER help system For more information on the ispLEVER de
3. This register is only available in the 8237 mode Each of the four channels has a 16 bit wide Current Address Reg ister that holds the value of the address used during DMA transfers The address is automatically incremented or decremented after each transfer The microprocessor loads the Current Address Register simultaneously with the Base Address Register If Auto Initialization is enabled the MCDMA reloads the base address value at the end of the DMA cycle This register has to be written in two consecutive cycles after clearing the byte pointer Current Word Count Register This register is only available in the 8237 mode Each channel has a 16 bit Current Word Count register that deter mines the number of transfers to be performed The actual number of transfers is one more than the value pro grammed into this register The Current Word Count is decremented after each transfer If Auto Initialization is enabled the value in the Base Word Count register is reloaded at the end of the DMA service When the value in the register goes from zero to OxFFFF a terminal count eopout_n signal is generated If Auto Initialization is not enabled this register has a count of OxFFFF at the end of DMA service Base Address Register This register is only available in the 8237 mode Each channel has a 16 bit Base Address Register This register stores the starting address for the transfer In the idle state or program condition the microprocessor simulta
4. N number of channels Timing Specifications Figure 3 illustrates the waveform for a write operation into one of the internal registers in the MCDMA core Clock edges 1 2 and 3 indicate the point where the data is written into the registers Clock edges 2 and 3 indicate a back to back write operation into the same register The iorin_n signal is held high during the entire write operation Figure 3 Processor Write Timing Waveform 1 2 3 Clock Xx N cs n gi gf 8 ile or TTT iowin_n SA S ain D a J N 7 7 77 i SL E T AS f Je dbin fi AU xf f sf f amp Y Y IFLA NF S N Figure 4 shows the processor read timing waveform Data is available on the following clock edge after cs_n and iorin_n are asserted Clock edges 1 2 and 3 indicate the edges on which the data is valid Lattice Semiconductor Multi Channel DMA Controller User s Guide Figure 4 Processor Read Timing Waveform VIJLEN RE X _XLLLLL dbout J j A i j A x Lattice Semiconductor Multi Channel DMA Controller User s Guide Figure 5 shows the timing waveform for two words DMA transfer Figure 5 Two Word DMA Transfer Timing Waveform a Ss Clock dreq XA hreq ee eee hida x aen Lon aout Y Valid A
5. a Terminal Count or external eopin_n is encountered or until dreq goes inactive Thus transfers continue until the I O device has exhausted its data capacity After the I O device has had a chance to catch up the DMA ser vice is reestablished by dreq Parameter Descriptions Table 3 lists the parameters used to configure the MCDMA core The values of these parameters must be set prior to functional verification The parameters in parenthesis can be configured using the IPexpress software tool included with the ispLEVER design tools Table 3 MCDMA Parameters Parameter Description Supported Values DMA Mode MODE 8237 Defines the DMA mode If it is TRUE the DMA will be in TRUE FALSE 8237 mode otherwise it will be in non 8237 mode Number of Channel Sets the number of channels In 8237 mode it is fixed to 4 4 8237 NUM_CHANNELS channels In non 8237 it can be set for 1 to 16 channels 1 16 non 8237 Data Width Sets the size of data buses and the temporary register 8 8237 DATA BUS WIDTH 8 16 32 64 non 8237 Address Width Sets the size of DMA output address In the 8237 mode it 16 8237 ADDR_BUS_WIDTH sets the size of the current and base address register In the non 8237 mode it sets the size of the source address regis ter 16 24 32 non 8237 Word Count Width Sets the size of the Word Count Register 16 8237 WORD_COUNT_WIDTH 8 16 24 32 non 8237 Internal Address Width Va
6. MEM MEM j 1 0 MEM Not Ready NR C i Ca S24 Write I I I I I i 8237 only I I I I I I I Phase Read Phase Compressed 8237 only Another Transfer Lattice Semiconductor Multi Channel DMA Controller User s Guide Table 2 State Descriptions State Description Idle State SI Upon reset the state machine enters the idle state SI The CPU can program the core s internal registers while it is in this state The device stays in this state until an unmasked DMA request is detected at which point the state machine asserts the hreq signal then transitions to state SO While in state SI all the outputs of the state machine are in their inactive states Input Signals hardware reset software reset only for 8237 mode unmasked dreq signal Asserted Output Signals hreq Possible State Transitions SI SO Acquire Bus State SO The device stays in this state until the hlda signal from the CPU is sampled asserted The internal registers can still be programmed while in this state Once the state machine samples and asserts the hlda signal it transitions to the state S1 for regular I O to memory or memory to I O DMA transfers For memory to memory transfers the state machine transitions to state S11 The criteria for detect ing a memory to memory transfer are different in the 8237 and non 8237 modes 8237 Mode In this mode a memory to memory transfer is detect
7. internal register when read by the CPU In the write to memory phase of the memory to memory DMA operation the dbout data bus transmits the data from the temporary register iowout_n Low Output IO Write Output This active low signal is used to load data to a peripheral during a DMA Read transfer Output Low memw_n Output Low memr_n Memory Write This active low signal is used to indicate that data is being written to the selected memory location during a DMA Write or a memory to memory transfer Memory Read This active low signal is used to indicate that data is being read from the selected memory location during a DMA Read or a memory to memory transfer 13 Lattice Semiconductor Multi Channel DMA Controller User s Guide Table 4 Signal Definitions of the MCDMA Controller Continued Port Name Type Active State Description aen Output High Address Enable This active high signal enables the 8 bit latch that contains the upper 8 address bits onto the system address bus aout ADDR_BUS WIDTH 1 0 Output N A Address Output These lines are enabled only during active DMA transfer and contain the memory address dack N 1 0 Output High Low DMA Acknowledge This signal is used to notify the request ing peripheral that it has been granted a DMA cycle The polarity of this signal is programmable A device reset initial izes all dack signals to active low Note
8. lpc 1450 432 562 N A 58 58 Non 8237 dma_mc_xp_2_002 lpc 3487 1072 1181 N A 124 66 1 Performance and utilization characteristics are generated using LFX1200B 05F900C in Lattice ispLEVER 3 x software The evaluation ver sion of this IP core only works on this specific device density package and speed grade 2 PFU is a standard logic block of some Lattice devices For more information check the data sheet of the device Supplied Netlist Configurations The Ordering Part Number OPN for all configurations of this core in ispXPGA devices is DMA MC XP N2 Table 21 lists the Lattice specific netlists that are available in the Evaluation Package which can be downloaded from the Lattice web site at www latticesemi com Table 21 Core Configuration ee Number of Channels Data Bus Width Address Bus Width Word Count Width 8237 Mode dma_mc_xp_2_001 lpc 4 8 16 16 Non 8237 Mode dma_mc_xp_2_002 pc 4 32 32 16 You can use the IPexpress software tool to help generate new configurations of this IP core IPexpress is the Lattice IP configuration utility and is included as a standard feature of the ispLEVER design tools Details regarding the usage of IPexpress can be found in the IPexpress and ispLEVER help system For more information on the ispLEVER design tools visit the Lattice web site at www latticesemi com software 25 Lattice Semiconductor Appendix for LatticeECP and LatticeEC FPGAs Tab
9. neously writes to the Base Address register and to the Current Address register The microprocessor cannot read this register Base Word Count Register This register is available only in the 8237 mode Each channel has a 16 bit Base Word Count register that stores the starting word count for DMA transfers During Auto Initialization this value is used to restore the current word count register The microprocessor cannot read this register Command Register This register controls the operation of the core In the 8237 mode this register is 8 bits wide In non 8237 mode it is 4 bits wide When DMA is in state idle the microprocessor programs this register A reset or master clear clears the register Table 6 lists the function of this register Lattice Semiconductor Multi Channel DMA Controller User s Guide Mode Register Each channel has a 6 bit wide register During a write operation by the microprocessor when MCDMA is in idle state the least two significant bits bit O and 1 of the data bus determine which channel mode register is being accessed A reset or a master clear clears the mode registers Table 7 lists the format of a mode register in the 8237 mode Mask Register This register is only visible in the 8237 mode Each channel has a bit associated with it that is used to mask a hard ware DMA request disable the incoming dreq All four bits of this register can be accessed at once or the CPU can program each of the bits separ
10. number of cycles taken to access this register depends on the size of the address bus During memory to memory transfers this register stores the address of the memory location that is written into This register is not used during DMA transfers between memory and I O The user must always program the register with the address that is aligned with the width of the data bus Word Count Register This register is only available in non 8237 mode and its width is configurable This register determines the number of transfers to be performed The actual number of transfers is one more than the value programmed into this reg ister The current word count is decremented after each transfer When the value in the register goes from zero to OxFFFF a Terminal Count eopout_n signal is generated At the end of a DMA transfer this register has a value of OxFFFF if auto initialization is not enabled for the channel 20 Lattice Semiconductor Multi Channel DMA Controller User s Guide Command Register This register controls the operation of the core This register is 4 bits wide in the non 8237 mode A reset or master clear clears the register Table 13 lists the functions of this register for the non 8237 mode Mode Register Non 8237 Mode Each channel has an 8 bit mode register Table 14 lists the format of the mode register in the non 8237 mode Pro gramming the corresponding increment and decrement bits to the same value can hold the source or dest
11. 8 16 24 or 32 bits Auto initialization Supported Supported Compressed timing Supported Not supported Cascade mode Not supported Not supported DMA transfer configuration for each channel Not supported Supported Priority request mode Rotating fixed priority mode Fixed priority mode DMA request active state High low High Software reset Supported Not supported Compatibility Differences with the 8237 Intel Device When the MCDMA core is configured for the 8237 mode it differs from the Intel 8237A core in the following ways e The bi directional ports are split into separate input and output ports e MCDMA does not support the cascade mode of operation e The latch that holds the upper byte of the address is internal and the address strobe signal ADSTB is not gener ated The slave s write cycle in the MCDMA core is synchronous Features e Selectable 8237 mode e Configurable up to 16 independent DMA channels for non 8237 mode e Configurable data width of 8 16 32 or 64 bits for non 8237 mode Configurable address width of 16 24 or 32 bits for non 8237 mode Configurable Word Count register width for non 8237 mode e Independent auto initialization of all channels e Memory to memory transfers on single block and demand transfer mode e Memory block initialization Lattice Semiconductor Multi Channel DMA Controller User s Guide e Software DMA requests Lattice Semiconductor Multi Channel DMA Controller User s Guide Bl
12. Lattice EEEE Semiconductor EELEE Corporation Multi Channel DMA Controller User s Guide February 2006 ipug11_04 0 Lattice Semiconductor Multi Channel DMA Controller User s Guide Introduction The Multi Channel Direct Memory Access MCDMA Controller is designed to improve microprocessor system per formance by allowing external devices to transfer information directly from the system memory and vice versa Memory to memory transfer capability is also supported The MCDMA Controller core supports two modes of operation 8237 and non 8237 modes When the 8237 mode is selected the core is functionally compatible with the Intel 8237A DMA Controller device with a few variations These variations are listed in the Compatibility Differences with the 8237 Intel Device section of this document The 8237 and non 8237 modes are detailed later in this document to provide a clearer description of each mode Differences Between 8237 Mode and Non 8237 Mode MCDMA While the 8237 and non 8237 modes share some commonality they also have differences Table 1 shows the dif ferences between the two modes Table 1 Feature Differences Between the 8237 and Non 8237 Modes Feature 8237 Mode Non 8237 Mode Multiple independent channels 4 1 16 Parameterized address bus Fixed 16 bits 16 24 or 32 bits Parameterized data bus Fixed 8 bits 8 16 32 or 64 bits Parameterized word count register Fixed 16 bits
13. Low IO Read Input This is an active low signal when asserted along with cs_n Thus it permits the CPU to read the internal registers of MCDMA YO Write Input This is an active low signal When asserted along with cs_n it permits the CPU to write into the internal registers of the MCDMA ain AIN BUS WIDTH 1 0 Input N A Address This signal selects one of the internal registers In the 8237 mode ain is 4 bits wide In the non 8237 mode the bus width depends on the number of channels selected dbin DATA BUS WIDTH 1 0 Input N A Data Bus Input The CPU writes to the internal registers through this data bus dreq N 1 0 Input High Low 8237 High Non 8237 hreq Output High eopout_n Low Output iorout_n Low Output dbout DATA BUS WIDTH 1 0 Output N A DMA Request These programmable parity signals are asyn chronous signals generated by peripherals requesting DMA service A device reset initializes dreq to active high In 8237 mode these parity signals are programmable to be active high or low In non 8237 these signals are always active high Hold Request This is an active high signal sent to the CPU to request control over the system bus End of Process Out This active low signal indicates normal termination of a DMA service I O Read Output This active low signal is used to access data from a peripheral during a DMA Write transfer Data Bus Output This bus contains the value of the
14. ad operation and states S21 S22 S23 S24 for the memory write operation Wait states are introduced whenever the slave device is not ready for the transfer MCDMA Transfer Modes When the MCDMA is in the active cycle the DMA service takes place in one of the following three modes e Single Transfer Mode In single transfer mode the device is programmed to make one transfer only Following each transfer the Word Count decrements and the address decrements or increment depending on what is selected in the Mode register To be recognized the dreq signal must be held active until dack becomes active If dreq is held active throughout the single transfer hreq goes inactive and releases the bus to the system After the transfer hreq will go active again When the controller receives a new hlda another single transfer will be performed Block Transfer Mode In block transfer mode dreq signals the device to continue making transfers during the ser vice until a terminal count is encountered generation of eopout_n This occurs when the word count goes to OxFFFF or an external End of Process eopin_n is encountered The dreq signal must be held active until dack becomes active Auto initialization occurs at the end of the service if the channel has been programmed for it Lattice Semiconductor Multi Channel DMA Controller User s Guide e Demand Transfer Mode In demand transfer mode the device is programmed to continue making transfers until
15. ately Each mask bit is set when its associated channel produces an eopout_n signal A reset or master clear sets all four bits and masks all the channels Table 8 and Table 9 list the mask regis ter format for the 8237 mode Request Register This register is only visible in 8237 mode The request register allows software DMA requests The values in the mask register mask the hardware request dreq Software requests generated from the request register are non maskable Individual bits of this register can be accessed with the channel number supplied on the two least signif icant bits of the data bus A reset or master clear clears this register The channel must be in block mode in order to make a software request Table 10 lists the request register format in 8237 Mode Status Register This register is only available in the 8237 mode The microprocessor can read the status register which contains information about the status of the device This information includes which of the channels have completed their DMA service and which channels have a DMA request pending The Status Register is reset upon a hardware reset or a master clear Bits 0 through 3 which indicate which channel has reached Terminal Count are cleared every time the Status register is read Bits 4 through 7 are set when their corresponding channel is requesting ser vice Table 11 shows the status register format Temporary Register This register holds data during memory to m
16. c way The registers visible to the microprocessor are different for the 8237 and non 8237 modes The MCDMA controller core is a fully synchronous machine that runs off the positive edge of the clock However the DMA request signals dreq N 1 0 are asynchronous with respect to the clock These signals have to be synchronized within the core DMA Initialization Once the Command and Mode registers are programmed and the controller is enabled DMA transfers can be initi ated either by asserting the unmasked channel s dreq signal or by requesting to DMA by programming the request register The internal registers of the core are accessible during the idle state SI when no channel is requesting service and no DMA transfers are in progress The core operates in two cycles Idle and Active The core remains in the idle cycle as long as it is not performing any DMA transfers and none of the unmasked channels have a pending request In this state the microprocessor can program the device Once an unmasked channel requests DMA service the device asserts the hreq signal to take control of the bus and enters the first active cycle state SO The device can still be programmed in the SO state until it receives the hlda signal from the bus arbiter For DMA transfers between memory and I O the active cycles go from states S1 through S4 When memory to memory DMA transfers are performed the active cycles go through states S11 S12 S13 S14 for the memory re
17. d register rolls over from OxFFFF to 0x0000 This causes the state machine to transition to state SI If block or demand transfer mode is selected the counter has not rolled over and DMA hasn t satisfied the transfer complete conditions the state machine transitions to a state where DMA transfers will continue This next state depends upon the mode of operation 8237 Mode The state machine transitions to state S2 as long as the higher order address remains the same If the higher order address for the new transfer changes the state machine transitions to state S1 to enable the external latch to update its latched value Non 8237 Mode The state machine transitions to state S2 Input Signals eopin_n Asserted Output signals eopout_n Possible State Transitions SI S1 S2 Compressed Timing Mode This feature is only available in the 8237 mode MCDMA The purpose of this mode is to allow MCDMA to achieve greater throughput by compressing the memory to I O or I O to memory transfer time to two clock cycles In this mode state S3 is removed from the state machine This causes the read pulse width to equal the write pulse width Thus the transfer only has state S2 to change the address and state S4 to perform a read write operation Priority Request Encoder This block prioritizes the DMA request and asserts the dack signal for the winning request In the 8237 mode the arbitrating scheme is user programmable and available i
18. ddress X Valid Address X dack iorout_n memr_n Ven iowout_n memw_n Note 1 Note 1 This timing diagram demonstrates the extended write operation In the 8237 mode when normal write operation is selected iowout_n or the memw_n is asserted one clock cycle later If compressed timing is selected the state S3 is bypassed making the read and write pulses of equal width This is only applicable in 8237 mode The iowout_n and memw_n signals are generated off the falling clock edge This ensures the address is held at least for half a cycle after the rising edge of the write signal 16 Lattice Semiconductor Multi Channel DMA Controller User s Guide Register Descriptions The 8237 and non 8237 modes of the MCDMA Controller have different types and number of internal registers The 8237 mode has ten types of internal registers that are visible to the microprocessor while the non 8237 mode has seven types of internal registers that are visible to the microprocessor 8237 Mode Internal Registers Table 5 Internal Registers in 8237 Mode Name Size in Bits Number of Registers Base Address Registers 16 4 Base Word Count Registers 16 4 Current Address Registers 16 4 Current Word Count Registers 16 4 Command Register 8 1 Status Register 8 1 Temporary Register 8 1 Mode Register 8 4 Mask register 8 1 Request Register 4 1 Current Address Register
19. de Bit Description 0 Clear Request bit Set Request bit Channel unmasked Channel masked Auto Initialization disable Auto Initialization enable 4 o o o Register Address Map The 8237 and non 8237 modes of the MCDMA Controller decode and use different numbers of ain bit input sig nals The ain signal is used for mapping the register address and decoding software command Table 16 Register Address Map and Software Command of 8237 Mode Write Read ain3 ain2 aini ain0 Channel iorin n 1 iowin n 0 iorin n 0 iowin n 1 0 0 0 0 Base and current Address reg Current DMA address reg 0 0 0 1 a Base and current Word Count reg Current Word Count reg 0 0 1 0 1 Base and current Address reg Current DMA address reg 0 0 1 1 Base and current Word Count reg Current Word Count reg 0 1 0 0 o Base and current Address reg Current DMA address reg 0 1 0 1 Base and current Word Count reg Current Word Count reg 0 1 1 0 3 Base and current Address reg Current DMA address reg 0 1 1 1 Base and current Word Count reg Current Word Count reg 1 0 0 0 X Command Register Read Status Register 1 0 0 1 X Single Request bit command Illegal 1 0 1 0 X Single Mask bit command Illegal 1 0 1 1 X Mode Register Illegal 1 1 0 0 X Clear Byte Pointer command Illegal 1 1 0 1 X Master clear command Read temporary reg 1 1 1 0 X Clear Mask Register command Illegal 1 1 1 1 X Mask regist
20. e state machine transitions to state S12 Input Signals eopin_n Asserted Output Signals aen address Possible State Transitions S12 Memory to Memory Read This is the second state of memory to memory transfer The memr_n signal is Transfer State Two S12 asserted The state transitions to state 13 Input Signals eopin_n Asserted Output Signals memr_n address Possible State Transitions S13 Lattice Semiconductor Multi Channel DMA Controller User s Guide Table 2 State Descriptions Continued State Memory to Memory Read Transfer State Three S13 Memory to Memory Read Transfer State Four S14 Memory to Memory Write Transfer State One S21 Memory to Memory Write Transfer State Two S22 Memory to Memory Write Transfer State Three S23 Description This is the third state of the memory to memory transfer The state machine sam ples the ready signal and stays in this state as long as it is asserted The machine transitions to state S14 when the ready signal is de asserted Input Signals eopin_n ready Asserted Output Signals memr_n address Possible State Transitions S13 S14 This is the fourth stage of the memory to memory transfer The state machine de asserts memr_n signal and asserts an enable signal to flop the incoming data into the temporary register The state machine transitions to state S21 which is the first state of the memory to memory write transfer
21. ed Channel 2 masked Channel 3 unmasked Channel 3 masked o o O O Table 9 Mask Register Access One Bit 8237 Mode Bit Description 1 0 00 Select channel 0 mask bit 01 Select channel 1 mask bit 10 Select channel 2 mask bit 11 Select channel 3 mask bit 2 O Clear mask bit 1 Set mask bit 7 3 Don t care Table 10 Request Register Access One Bit 8237 Mode Bit Description 1 0 00 Select channel 0 request bit 01 Select channel 1 request bit 10 Select channel 2 request bit 11 Select channel 3 request bit 2 O Clear request bit 1 Set request bit 7 3 Don t care 19 Lattice Semiconductor Multi Channel DMA Controller User s Guide Table 11 Status Register Access One Bit 8237 Mode Do _ Description Channel 0 terminal count Channel 1 terminal count Channel 2 terminal count Channel 3 terminal count Channel 0 request Channel 1 request Channel 2 request NI a S oO N o Channel 3 request Table 12 Non 8237 Internal Registers Name Size in Bits Number of Registers Source Address Register 16 24 or 32 N4 Word Count Register 8 16 24 or 32 N Destination Address Register 16 24 or 32 N Command Register 4 1 Temporary Register 8 16 32 or 64 1 Mode Register 8 N Channel Control Register 3 N 1 Based on the width of the address bus selected 2 Ba
22. ed if the memory transfer enable bit in the Command register is set and the dreq 0J signal is asserted The dackout signal generated by the priority encoder is used to check if Channel 0 has the highest priority at that time The DMA priority scheme will be described more in the priority request encoder section Non 8237 Mode In this mode memory to memory transfer is detected if bit zero of the current channel s mode register is set If the current channel s dreq signal is de asserted in this state and no other requests are pending the state machine transitions to state SI If other requests are pending or the dreq signal remains asserted the state transitions to either S1 or 11 Input Signals hlda command 0 or mode 0 dackout Asserted Output Signals hreq Possible State Transitions SI S1 S11 Memory to Memory Read This is the first state of the memory to memory transfer The absence of the dack Transfer State One S11 signal characterizes this transfer The aen signal is asserted In the 8237 mode the address from Channel 0 of the current address register is placed on the address bus In the non 8237 mode the contents of the source address register are placed on the address bus The memr_n and memw_n signals are de asserted During each of the eight states of the memory to memory transfer the state machine responds to external eopin_n signal and stops the DMA transfer service as soon as the cur rent cycle is completed Th
23. emory transfers A reset or master clear command clears this register The microprocessor can read this register in the 8237 mode while the MCDMA is in the idle state This register yields the last data transferred during the most recent memory to memory transfer Table 6 Command Register 8237 Mode Bit Description 0 Memory to memory disable Memory to memory enable 1 Channel 0 address hold disable Channel 0 address hold enable X if bit0o 0 2 Controller enable Controller disable 3 Normal timing Compressed timing X if bitO 1 4 Fixed Priority Rotating Priority 5 Late Write Extended Write X if bits 1 6 dreq active high dreg active low 7 dack active low dack active high Lattice Semiconductor Multi Channel DMA Controller User s Guide Table 7 Mode Register 8237 Mode Bit Description 1 0 00 Channel 0 select 01 Channel 1 select 10 Channel 2 select 11 Channel 3 select 3 2 00 Verify transfer 01 Write transfer 10 Read transfer 11 Illegal xx If bits 6 amp 7 are 11 4 O Auto initialization disable 1 Auto initialization enable 5 O Address increment 1 Address decrement 7 6 10 Demand mode select 01 Single mode select 10 Block mode select 11 Cascade mode unsupported Table 8 Mask Register Access All Bits 8237 Mode Bit Description 0 Channel 0 unmasked Channel 0 masked Channel 1 unmasked Channel 1 masked Channel 2 unmask
24. er s contents during the register read cycle or the temporary register contents during the memory write cycle of a memory to memory transfer DMA Finite State Machine The DMA FSM Finite State Machine module initiates data transfers and generates control signals for various transfer modes It also generates the address and address enable signals aen The FSM exchanges signals with the CPU interface block and priority encoder block The state machine in the 8237 mode is similar to the non 8237 mode except a few additional FSM branches in 8237 mode that incorporate Lattice Semiconductor Multi Channel DMA Controller User s Guide Illegal I O to memory transfer mode bits e Compressed timing mode FSM Operation When a software or hardware request is received and is found to be valid having passed the polarity mask and mode checks the DMA FSM in SI Idle state transmits a request signal hreq to the CPU and transitions to SO and waits for the hlda signal If the request drops dreq is de asserted or the mode register of the request in hand is in cascade mode unsupported the FSM returns to SI idle Otherwise the FSM remains in SO Once the request is acknowledged by the assertion of hlda signal the FSM transitions to S1 S11 S1 and S11 are synony mous The FSM also determines the transfer type based on the Command and Mode register that is received from the CPU interface If memory to memory transfer is enabled the FSM tra
25. er Illegal In the 8237 mode the additional software commands are Clear Byte Pointer Master Clear and Clear Mask Regis ter Table 17 Register Address Map and Software Command of Non 8237 Mode Write iorin_n 1 iowin n 0 ain2 aint ain0 Read iorin_n 0 iowin_n 1 0 0 0 Command register 0 0 1 Source Address register 0 1 O Word Count register 0 1 1 Destination Address register 1 0 O Moderegister 1 0 1 Channel Control register 1 1 O0 Master Clear command 1 1 1 Clear Byte Pointer command 22 Lattice Semiconductor Multi Channel DMA Controller User s Guide Programming the MCDMA Controller Programming the core to achieve the desired functionality is very similar in both the 8237 and non 8237 modes The differences lie in the address map and the name of the registers For the 8237 mode the steps to program the core are e Disable the controller through the command register e Program the Mode Register Select the channel to be programmed Set the features on the channel to programmed such as transfer mode read write verify transfer address increment decrement etc e Write into the Address Registers and Word Count Register Set the base source address register Set the number of transfer to be performed in the Word Count Registers e Enable the controller For the non 8237 mode the steps to program the core are e Disable the controller e Se
26. iming option is selected This will result both read and write pulses being asserted for just a single cycle Non 8237 Mode memw_n or iowout_n is asserted and the state machine transi tions to state S3 While in state S2 S3 or S4 the state machine will terminate a block or demand transfer if the eopin_n signal is sampled asserted Input Signals eopin_n dreq Asserted Output Signals dack memw_n memr_n iorout_n iowout_n Possible State Transitions S3 S4 Active DMA state three S3 This is the third state of the DMA transfer In the 8237 mode the memw_n or iowout_n signal is asserted if extended write is not selected The state machine is sensitive to the eopin n and dreq signals for demand transfers The state machine transitions to state S4 when ready signal is sampled de asserted The machine stays in state S3 as long as ready is sampled asserted Input Signals eopin_n dreq ready Asserted Output Signals memw_n iowout_n Possible State Transitions S3 S4 Lattice Semiconductor Multi Channel DMA Controller User s Guide Table 2 State Descriptions Continued State Description Active DMA state four S4 This is the last stage of the DMA transfer The memw_n or iowout_n signal is de asserted depends on the operation I O to memory or memory to I O The same thing happens to the memr_n or iorout_n signal for only one of them being de asserted The eopout_n signal is asserted if the current wor
27. ination address constant Channel Control Register This register is visible in the non 8237 mode Each channel has one channel control register Table 15 lists the reg isters format A reset or a master clear resets the request and sets the mask This masks the channel s hardware requests Auto initialization is disabled upon a reset Table 13 Command Register Non 8237 Mode Bit Description 0 0 Controller enable 1 Controller disable 1 Reserved This bit is always 0 2 Reserved This bit is always 0 3 O dack active low 1 dack active high Table 14 Mode Register Non 8237 Mode Bit Description 0 0 Memory to memory disable 1 Memory to memory enable 1 O Write transfer 1 Read transfer X Ifbit0 1 2 O Increment Source Address disable 1 Increment Source Address enable 3 0 Decrement Source Address disable 1 Decrement Source Address enable 4 0 Increment Destination Address disable 1 Increment Destination Address enable 5 0 Decrement Destination Address disable 1 Decrement Destination Address enable 7 6 00 Demand mode select 01 Single mode select 10 Block mode select 11 Illegal Note Bits 2 and 3 are mutually exclusive They cannot be enabled at the same time since the address will either increment or decre ment This also applies to Bits 4 and 5 21 Lattice Semiconductor Multi Channel DMA Controller User s Guide Table 15 Channel Control Register Non 8237 Mo
28. lds the memory location address during DMA transfers between an I O device and memory Lattice Semiconductor Multi Channel DMA Controller User s Guide The functionality of the core in the non 8237 mode is very similar to that of the 8237 mode However the two modes have totally different sets of programmable control registers This increases the programmability features in the non 8237 mode Some of the features available only in the non 8237 mode are e Multiple channels e Configurable channels for DMA transfers between memory and memory or I O and memory e Parameterized address output and data bus width e Parameterized word count register The microprocessor programs a number of registers to ensure the DMA controller functions properly The internal registers are accessed when the cs_n signal is asserted and the address of the register is placed on the ain bus When the iowin_n signal is low the registers are over written with the data on dbin bus When the iorin_n sig nal is asserted the registers are read and their contents are placed on the dbout bus The least significant eight bits of the data bus can access the internal registers irrespective of the data bus width To prevent erroneous behavior the DMA registers should be programmed only when the controller is in the Idle State SI or before it receives the hlda signal from the microprocessor Not adhering to these rules will cause the DMA controller to function in a non deterministi
29. le 22 Performance and Resource Utilization Multi Channel DMA Controller User s Guide Name of sysMEM Mode Parameter File SLICEs LUTs EBRs Registers 1 0 fmax MHz 8237 dma_mc_e2_3_001 lpc 710 1087 0 551 59 72 Non 8237 dma_mc_e2_3_002 Ipc 1633 2249 0 1181 125 86 1 Performance and utilization characteristics are generated using LFEC20E 4F672C in Lattice ispLEVER 4 1 software When using this IP core in a different density package or speed grade performance may vary Supplied Netlist Configurations The Ordering Part Number OPN for all configurations of this core in LatticeEC devices is DMA MC E2 N3 Table 23 lists the Lattice specific netlists that are available in the Evaluation Package which can be downloaded from the Lattice web site at www latticesemi com Table 23 Core Configuration sere Fia Number of Channels Data Bus Width Address Bus Width Word Count Width 8237 Mode dma_mc_e2_3_001 lpc 4 8 16 16 Non 8237 Mode dma_mc_e2_3_002 Ipc 4 32 32 16 You can use the IPexpress software tool to help generate new configurations of this IP core IPexpress is the Lattice IP configuration utility and is included as a standard feature of the ispLEVER design tools Details regarding the usage of IPexpress can be found in the IPexpress and ispLEVER help system For more information on the ispLEVER design tools visit the Lattice web site at www latticesemi com software
30. lue is set automatically based in the number of channels 4 8237 AIN BUS WIDTH parameter NUM_CHANNELS or N 3 when N 1 non 8237 4 when N 2 non 8237 5 when 3 lt N lt 4 non 8237 6 when 5 lt N 8 non 8237 7 when 9 lt N lt 16 non 8237 12 Lattice Semiconductor Signal Descriptions Multi Channel DMA Controller User s Guide Table shows the input and output ports of the MCDMA core that apply for both 8237 and non 8237 modes Table 4 Signal Definitions of the MCDMA Controller Port Name Type Active State Description clk Input Rising Edge Clock This signal controls and synchronizes the operations of the MCDMA cs n Low Input Chip Select This is an active low signal used to select the MCDMA reset Input High ready Input High Reset This is an active high signal that clears the internal registers After reset the device is placed in the Idle state and the DMA requests are masked Ready This is an active high signal used to extend the mem ory read and write pulses from the MCDMA This is most of often used to accommodate slow memories hlda Input High Hold Acknowledge This active high signal generated by the CPU indicates the CPU has relinquished control of the sys tem buses eopin_n Input Low End Of Process Input This active low input permits the external termination of the current DMA service iorin_n Input Low iowin_n Input
31. n either a fixed priority or rotating priority mode In non 8237 operation the arbitrating scheme is restricted to the fixed priority mode In the fixed priority mode dreq 0 has the highest priority and dreq n has the lowest priority In the 8237 mode n channel number is fixed to 3 while in the non 8237 mode n is user selectable up to 16 The rotating priority mode assigns the lowest priority to the channel that has been serviced most recently This mode ensures that all devices will be serviced fairly and prevents any one channel from monopolizing the system The maximum wait time for a channel to be serviced is the time taken to service all the other channels The main function of this block is to generate the dack x signal Each channel has an associated priority register that indicates the channel s priority In the fixed priority mode the values in these registers will never change while in the rotating priority mode their values change every time a channel is serviced DMA Operation In the non 8237 mode each channel can be programmed to perform DMA operation between memory locations or from I O to memory Each channel has a dedicated source address register that holds the address of the targeted read memory location and a destination address register which points to the targeted write memory location Memory locations are addressable but I O locations are not addressable The source address register in the non 8237 mode ho
32. nsitions through states S12 S13 14 S21 22 S23 and S24 If the next transfer should continue for the same request the path from S11 to S24 is repeated If memory to l O or I O to memory is enabled the FSM goes through states S2 S3 eliminated in 8237 s compressed timing mode and S4 If the transfer continues the state machine repeats the loop from S2 through S4 This goes on until the Word Count register gets an overflow or a termination from an external input occurs External inputs that can termi nate a transfer includes an eopin_n or hlda drop or a request drop during demand transfer Note In case of a non demand transfer the request can be dropped after dack is received The eopout_n signal is generated on the falling clock edge of S4 or S24 by the end of the transfer All transfer read write signals are generated on the falling edge of clock In the state machine described in Figure 2 input signals refer to the signals that the state machine samples These signals affect the state machine s transition logic Output signals refer to signals that will be asserted or de asserted transition while in that state Lattice Semiconductor Multi Channel DMA Controller User s Guide Figure 2 MCDMA Finite State Machine for 8237 and Non 8237 Modes Request LAST_TRAN ee SINGLE_TRAN Du No HDLA Illegal Termination Oge IO Mode LAST_TRAN SINGLE_TRAN Termination Not LAST_TRAN NR S1 S11 A
33. ock Diagram Figure 1 shows the block diagram of this core Figure 1 Block Diagram of MCDMA Core csn gt gt hreq eopin_n gt aen reset ____ gt iorout_n clk gt gt gt iowout_n i CPU Pa Senh ready prg gt memw_n hida gt eopout_n ain AIN_BUS_WIDTH 1 0 LIL dbin DATA_BUS_WIDTH 1 0 aout ADDR_BUS_WIDTH 1 0 Register Block dbout DATA_BUS_WIDTH 1 0 LI ln CT dreq N 1 0 Request Encoder dack N 1 0 N Number of channels Functional Description The MCDMA contains three basic blocks of control logic CPU Interface Data and Control Blocks the DMA State Machine and the Priority Request Encoder CPU Interface Control This explanation applies mainly to the non 8237 mode because most of the programmability lies in this mode How ever the concepts are also applicable to the 8237 mode The CPU Interface Control block first decodes the ain bus It then generates the enable signals to the selected registers or to a subset of the selected registers when byte enables are present during the write cycle When the registers are read it provides a select signal to the multiplexer that routes the appropriate register contents onto the data bus CPU Interface Data The CPU Interface Data block contains all the configuration registers It includes all the routing logic required to transfer either the selected regist
34. ound in the IPexpress and ispLEVER help system For more information on the ispLEVER design tools visit the Lattice web site at www latticesemi com software 28
35. rts the memw_n signal In the 8237 mode Channel 1 s current word register is decremented In the non 8237 mode the word count register of the channel being serviced is decremented If the counter rolls over from OxFFFF to 0x0000 the eopout_n signal is asserted and the state machine transitions to state SI Otherwise the state machine transitions to state S11 and starts a new memory to memory transfer Input Signals eopin_n Asserted Output Signals eopout_n in case the counter rolls over Possible State Transitions SI S11 This is the first state of DMA transfer The aen signal is asserted in this state while a valid address is placed on the address bus If dreq continues to be asserted the state machine transitions to state S2 If dreq is de asserted the state machine transitions to state SI DMA requests must be held active until the dack signal is asserted Input Signals dreq Asserted Output Signals aen address Possible State Transitions S2 SI Active DMA state two S2 This is the second state of the DMA transfer The dack signal is asserted The dreq signal does not need to be held asserted after this state if block or single transfer mode is selected memr_n or iorout_n is asserted depending on the direction of the transfer 8237 Mode memw_n or iowout_n is asserted if the extended write option is selected in the command register The state machine will skip state S3 and transi tion to state S4 if the compressed t
36. sed on the width of the word count register selected 3 Based on the width of the data bus selected 4 N Number of channels selected Source Address Register This register is only available in the non 8237 mode Each channel has a Source Address Register whose width matches with the address bus width This register stores the value of the source or memory address used during DMA transfers The address is automatically incremented or decremented by 1 2 or 4 after each transfer depend ing on the respective data bus width of 8 16 or 32 bits This register has to be written in consecutive cycles after clearing the byte pointer The number of cycles taken to access this register depends on the size of the address bus During a DMA transfer between an I O location and memory this register holds the address of the memory location During a memory to memory transfer this register stores the address of the location that is read from The user must always program the register with the address that is aligned with the width of the data bus Destination Address Register This register is only available in the non 8237 mode Each channel has a Destination Address Register whose width matches with the address bus width The address is automatically incremented or decremented by 1 2 or 4 after each transfer depending on the respective data bus width of 8 16 or 32 bits This register has to be written in consecutive cycles after clearing the byte pointer The
37. sign tools visit the Lattice web site at www latticesemi com software 27 Lattice Semiconductor Multi Channel DMA Controller User s Guide Appendix for LatticeSC FPGAs Table 26 Performance and Resource Utilization sysMEM Mode Name of Parameter File SLICEs LUTs EBRs Registers I Os fmax MHz 8237 dma_mc_sc_3_001 lpc 717 1249 0 534 59 gt 100 Non 8237 dma_mc_sc_3_002 lpc 1744 2864 0 1179 125 gt 100 1 Performance and utilization characteristics are generated using LFSC3GA25E 5F900C in Lattice ispLEVER 5 1 SP2 software When using this IP core in a different density package or speed grade performance may vary Supplied Netlist Configurations The Ordering Part Number OPN for all configurations of this core in LatticeSC devices is DMA MC SC N3 Table 27 lists the Lattice specific netlists that are available in the Evaluation Package which can be downloaded from the Lattice web site at www latticesemi com Table 27 Core Configuration Name of Parameter File Number of Channels Data Bus Width Address Bus Width Word Count Width dma_mc_sc_3_001 lpc 4 8 16 16 dma_mc_sc_3_002 lpc 4 32 32 16 You can use the IPexpress software tool to help generate new configurations of this IP core IPexpress is the Lattice IP configuration utility and is included as a standard feature of the ispLEVER design tools Details regarding the usage of IPexpress can be f
38. stage Input Signals eopin_n Asserted Output Signals none Possible State Transitions S21 This is the fifth stage of the memory to memory transfer mode In the 8237 mode the content of the current address register on Channel 1 is put on the address bus In the non 8237 mode the content of the destination address register on the chan nel being serviced is put on the address bus The memr_n and memw_n signals are de asserted The state machine transitions to state S22 Input Signals eopin_n Asserted Output Signals address Possible State Transitions S22 This is the fifth state of memory to memory transfer The state transitions to state 23 Input Signals eopin_n Asserted Output Signals address Possible State Transitions S23 This is the seventh state of the memory to memory transfer The memw_n signal is asserted and the content of the temporary register is placed on the data bus The state machine samples the ready signal and stays in this state as long as it is asserted Then the machine transitions to state S24 Input Signals eopin_n ready Output Signals memw_n Possible State Transitions S23 S24 Lattice Semiconductor Multi Channel DMA Controller User s Guide Table 2 State Descriptions Continued State Memory to Memory Write transfer state four S24 Active DMA State One S1 Description This is the eighth and final stage of the memory to memory transfer The state machine de asse
39. t Input ain The first 3 bits of ain ain 2 0 selects which registered to be programmed The rest of the bits select which channel to be programmed e Program the Mode and Channel control registers of all the channels e Write into the Address registers and Word Count register e Enable the controller The core remains in the idle state SI as long as DMA transfers are not requested While in state SI the dreq sig nals are sampled When an unmasked DMA request is presented the core enters the active state The request can be either a software or hardware request Although the internal registers can be programmed in state SO or before the hlda signal is asserted it is a good practice to program the internal registers only while the core is in the Idle state SI The functionality of the control ler is not guaranteed to be deterministic if the internal registers are accessed during an active DMA cycle Reference Information e ispLEVER Software User Manual Lattice Semiconductor Corporation e 8237A High Performance Programmable DMA Controller Intel Corporation September 1993 Technical Support Assistance Hotline 1 800 LATTICE North America 1 503 268 8001 Outside North America e mail techsupport latticesemi com Internet www latticesemi com 23 Lattice Semiconductor Multi Channel DMA Controller User s Guide Appendix for ORCA Series 4 FPGAs Table 18 Performance and Resource Utilization
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