ST7540 power line modem firmware stack
Contents
1. The stack firmware uses some microcontroller peripheral libraries which must be considered to calculate the final code size The used STM32F103xx microcontroller libraries are listed below stm32f 10x_gpio stm32f10x_exti stm32f10x_spi stm32f10x_rtc e stm32 10x_bkp stm32 10x_iwdg stm32r10x rec stm32f10x tim lt time h gt Doc ID 023619 Rev 1 23 27 Stack firmware structure UM1573 Table 1 Stack firmware module data size IAR ELF Linker V6 30 1 53127 W32 for ARM Copyright 2007 2011 IAR systems AB ro code ro data ne ae QC DO O O O where rocode bytes of read only code memory ro data bytes of read only data memory rw data bytes of read write data memory lt 24 27 Doc ID 023619 Rev 1 UM1573 4 References References 1 ARM based 32 bit MCU STM32F10x Standard Peripheral Library Rel 3 5 0 2011 2 ST7540FSK power line transceiver datasheets 2006 3 AN3046 application note 4 IAR embedded workbench IDE Rel 6 3 documentation www iar com Doc ID 023619 Rev 1 25 27 Revision history UM1573 5 Revision history Table 2 Document revision history ICE CORSE E 12 Nov 2012 Initial release 26 27 Doc ID 023619 Rev 1 ky UM1573 Please Read Carefully Information in this document is provided solely in connection with ST products STMicroelectronics NV and its subsidiaries ST reserve the right to make changes corrections modifications or2. uint8_t PLM SPI PreemptvyPriority uint8_t PLM SPI SubPriority uint8_t PLM _CDPD_ PreemptyPriority uint8_t PLM CDPD SubPriority PLM_IntPriorityInitTypeDef Figure 6 ST7540 driver structure PLM ST7540 DRIVER 5T 540 APIs GPIO Std Peripheral Lib EXTI Std Peripheral Lib SPI Std Peripheral Lib AM15248v1 Next the ST7540 is configured and programmed by the following function void PLM Init PLM_InitTypeDef PLM_InitStruct This routine sets up all the modem parameters and initializes its internal registers The structure passed to the API is the following typedef struct PLMFreg_TypeDef PLM BandpassFrequency PLMBaudrate_TypeDef PLM BaudRate uint16_t PLM HeaderPreamble PLMDeviation_TypeDef PLM_Deviation PLMPrefilter_TypeDef PLM_PreFilter PLMSensitivity_TypeDef PLM_Sensitivity PLM_InitTypeDef In the stm32f10x_p1m h file all the typedefs of the previous structure with the admitted values for the PLM parameters are defined The following APIs are used for the ST7540 peripheral management and are the starting point for implementing its own stack firmware Doc ID 023619 Rev 1 9 27 ST7540 stack firmware code UM1573 2 1 1 10 27 The first group returns some flags indicating if the band is in use by another device if the current data frame has been sent or a data frame is received and if the received frame is a valid frame uineg E PLM_BandInUse void uint8_t PLM_FrameSent void
3. Each node can also act as a data repeater without any additional programming features increasing both the reliability of the network and the statistical probability that the information from the master to the slave is delivered even under difficult network conditions However the coexistence of more than one master and more repeaters introduces the need for data collision management Since more than one device can initiate communication at any time this may cause a network jam lowering overall performance This potential problem can be solved using one of two main techniques One of these carrier sense multiple access with collision detect CSMA CD is used when a hardware device is able to detect any collision during the data transmission The other carrier sense multiple access with collision avoidance CSMA CA the one used with this transceiver is used when the hardware does not have this capability Figure 1 CSMA CA BACKOFF BACKOFF TRANSMISSION sate BAND IN BAND IN USE BAND IN BAND IN USE AM15243v1 BACKOFF BACKOFF BACKOFF BACKOFF O TRANSMISSION BAND IN BAND IN USE BANDFREE FREE BACKOFF TRANSMISSION BAND FREE i lt a BAND IN BAND IN USE BAND IN BAND IN USE se BAND IN USE BAND FREE BACKOFF BACKOFF BACKOFF BACKOFF TRANSMISSION I I I The implemented conflict avoidance mechanism uses a backoff time and the band in use BU hard
4. discharged or processed A data identification technique frame ID and the forward error correction redundancy FEC in the data frames are implemented in order to avoid cyclic repetitions or data loss that can cause an unnecessary increase of data traffic Doc ID 023619 Rev 1 5 27 ST7540 stack firmware code UM1573 2 6 27 ST7540 stack firmware code The firmware implementing the network model previously described is structured in several layers each one performing different operations Figure 3 Firmware structure of the power line modem USER APPLICATION LAYER PLM STACK NETWORK INTERFACE DATA LINK PLM ST7540 DRIVER PHYSICAL LAYER POWER LINE AM15245v1 There are three types of frame that can be sent to the power line modem The first are data frames which contain the user data to send The second are programming frames which normally contain the programming parameters of the node like the node unique address or other user defined programming parameters normally used when the node is set up using external software such as a graphical user interface or an external device The last are service frames which contain parameters as well as the PLM stack parameters including timing and data repetitions or user defined service parameters The service frames also include parameters that set the node working model which are dependent on the
5. ulnes_t PLM FrameArrived void uint8_t PLM _ValidFrameArrived vold The next group of APIs is used to send and receive a data frame void PLM SendDatal uint8 butter uint8g_ t len void PLM StartReceiveData void uint8_t PLM GetBufferLength void Uints E PLM GetReceivedBufferPointer void There are also some APIs used for low level statistics returning the number of FEC corrections done in the arrived frame and the wrong postamble indication uint8_t PLM GetFECCorrections void PLM_WP_TypeDef PLM GetWrongPostamble void The last group of driver APIs are used for the PLM reset and internal register write read operations void PLM Reset void void PLM WriteRegisters uint8_t buffer uint8_t len void PLM StartReadRegisters void PLM initialization In this section the instructions sequence on how to configure and use the ST7540 driver is shown First the PLM must be initialized and configured by filling the init structures PLM IntPriorityInitTypeDef PLM InterruptiInitStructure PLM InitTypeDef PLM _InitStructure Configuring the PLM device and setting the correct interrupt priorities defined in the macros PLM SPI _INT_ PREEMPTY PRIORITY and PLM_SPI_INT_SUB_ PRIORITY for the SPI and PLM_CDPD_ PREEMPTY PRIORITY and PLM_CDPD_SUB_PRIORITY for the CDPD external interrupt pin is done with the instructions PLM InterruptInitStructure PLM_SPI_PreemptyPriority PLM SPI _INT_PREEMPTY PRIORITY P
6. MODE DEFINITION Ra ac i ac lg ie ei ines ee les ee eee ee E Comment the definition to disable the equivalent option Use the internal RTC define DEVICE _USE_RTC Use the external 32KHz oscillator for RTC functions define DEVICE _USE_EXTOSC_32KHZ Enable the internal watchdog for auto reset define DEVICE _USE_ WATCHDOG Enable the internal oscillator calibration if external oscillator is not used define DEVICE _LSI_TIM MEASURE Enable the ACK frames transmission link stack level define DEVICE _WM_REQ ACK Enable the back ACK frames transmission link stack level define DEVICE _WM_REQ bACK Enable the repeater mode define DEVICE _WM_REPEATER Enable to repeat all frames after the ACK timeout static repeater behaviour previous option must be enabled too define DEVICE _WM_REPEAT ALL Enable the AES128 data encryption define DEVICE _WM_ENCRYPT_DATA Enable the grouping filter for subnets define DEVICE _ WM _GROUP_FILTER Hoping commented 0 or 1 disabled higher value higher level Minimum allowed value 2 define DEVICE_HOP_LEVEL The following parameters set up the configuration mode of the transceiver It s important to set the PLM communication frequency at the same value of the middle frequency of the bandpass filter used in the hardware PLM communication frequency define PLM FREQ 60KHZ PLM comm frequ
7. TargetDeviceGroup Or use as address user_data address TargetDeviceAddress user_data framelen PAYLOAD SIZE user_data frametype NL_CLS_DATA_FRAME Data frame is selected Load user data to transmit for i 0 i lt PAYLOAD_SIZE i user_data databuffer i UserData i If the frame must be sent in broadcast the fields user_data group and user_data address can be set to 0 they are ignored by the other devices and the broadcast flag must be added to the frame type user _data frametype LL BROADCAST FLAG Send data in broadcast The returned values are the same as for the data reception service where the N_SUCCESS value indicates the correct data transfer with the assurance of data packet delivery The resulting cases are the same as those of the indication service if nNStatus operation N_DOING PL IDLE MODE User application while data is being transmitting via PLM else if nNStatus operation N_ERROR PL DATA TRANSMISSION ERROR Error Management else if nNStatus operation N_SUCCESS PL DATA TRANSMITTED lt Doc ID 023619 Rev 1 UM1573 2 2 4 lt ST7540 stack firmware code Data delivery to the target device successfull Other stack interface APIs In the network interface file stk_n h there are some other APIs that can be used in the user application The first of which is a function used to reset the state machines and
8. es 23 4 ReIerenceS arauraeiaini bi A E i 25 5 Revision history ac asc nlesiia pi ea lieta teehee ewes 26 2 27 Doc ID 023619 Rev 1 ky UM1573 List of figures List of figures FIOUTS COMA CA ccebda rado AA LIA Lt 4 Figure 2 Data exchange diagram ccc ee eee eee ene eens 5 Figure 3 Firmware structure of the power line Modem 6 Figure 4 Data communication flow with a case of repetitioN LL 7 Figure 5 Firmware stack block diagram 8 Figure 6 ST7540 driver structure 0 0 ce eet ee eee teense 9 Figure 7 Stack working mode bitmap definition 18 Figure 8 Stack firmware Structure 23 ky Doc ID 023619 Rev 1 3 27 Network model description 4 27 Network model description The power line modem firmware stack is designed to manage a network structure composed of several power line modems called nodes These modem nodes are distributed throughout the power line One or more modems can be used as a data UM1573 concentrator and the others as slave modems All the nodes and the concentrator share the same power line which is used as a data communication channel physical means The network is logically designed to be a master slave structure where the data concentrator is considered a master device and each addressed node is the slave And in fact any device can initiate the communication thereby becoming a master while the target node having a unique address ID becomes the slave device
9. lt 77 UM1573 Y User manual ST7540 power line modem firmware stack Introduction This document explains how to use the firmware stack protocol designed for an STM32F103xx microcontroller interfaced with an ST7540 FSK power line transceiver The firmware is organized in a layer structure and is able to drive the ST7540 transceiver implementing a communication protocol for the data transfer between two or more devices connected to the same power line The stack is also able to manage the possible conflicts the data acknowledgement and the repetitions in the case of data loss This firmware stack is developed using the STM32F103xx Standard Peripherals Library Rel 3 5 0 and IAR Embedded Workbench IDE for STM32F103xx microcontrollers Rel 6 3 November 2012 Doc ID 023619 Rev 1 1 27 www st com Contents UM1573 Contents 1 Network model description ina 4 2 ST7540 stack firmware code 0 6 2 1 ST 7540 driver layer o 8 2 1 1 PIENIMANQIZAION ssaa iridati 10 2 1 2 Receiving data from power line Modem 11 2 1 3 Transmitting data to power line modem 11 2 2 Data link and network level 12 2 2 1 Stack initialization persero ito 16 2 2 2 Stack data reception service NL_NetworkIndication 18 2 2 3 Stack data transmission service NL_NetworkRequest 20 2 2 4 Other stack interface APIS 0 0 0 cc eee 21 3 Stack firmware structure
10. network model to implement for example with or without acknowledgement broadcast behavior repetition mode In any case each frame type here described is treated in the same manner by the stack and transferred to from the user application layer from to the power line modem A particular frame is the ping frame which is used to ping a remote node As well as the remote node receiving these kinds of frames the acknowledgement is given directly by the stack engine without notification to the upper levels The same behavior is done with the acknowledgement frames ACK and bACK to the data service or programming frames which are managed directly by the stack In the PLM stack level the user information is packed and added with the necessary information such as FEC and cyclic redundancy check CRC and sent to the PLM This works both ways if the PLM catches proper data packets these are managed by the stack Doc ID 023619 Rev 1 ky UM1573 ST7540 stack firmware code The FEC is used to correct wrong data if any the CRC is also checked and if valid data are decoded these are sent to the user application level The PLM stack directly manages the repetitions the necessary timing and acknowledgements If the target device does not acknowledge a data frame each neighboring node with the repetition feature enabled that has sensed the transited data frame forwards it after the acknowledge timeout as long as the band is not alr
11. restart the engines void NL _NetworkRestart void In order to know or to set the current stack settings and working mode the following APIs are available Working mode DNL_DLSP_t defined in stk_n h file void NL_GetDataLinkStackParameters NL_DLSP_t llsp void NL_SetDataLinkStackParameters NL_DLSP_t llsp Get API s uint8_t NL _GetLocalWorkingMode void uint8_t NL _GetLocalHopLevel vold void NL_GetLocalAddress uint16_t nDevGrp uint32_t nDevAdd Set API s void NL_SetLocalAddress uint16_t nDevGrp uint32_t nDevAdd void NL_SetLocalWorkingMode uint8_t wmode void NL_SetLocalHopLevel uint8_t hlevel To set up the working mode it is possible to set the single flag without changing the value of the other flags void NL_SetLocalWorkingModeFlag NL_WMFlag_t flag NL_WMFlag_status_t sts The following is a list of the flags and the values those flags can assume typedef enum i F_BROADCAST 0x01 F_ACK 0x02 F_bACK 0x04 F_REPEATER 0x08 F_GROUP 0x10 NL_WMFlag_t typedef enum Doc ID 023619 Rev 1 21 27 ST7540 stack firmware code UM1573 22 27 F ENABLED F_ DISABLED NL_WMFlag_status_t If the AES128 encryption is enabled the function to use to set up the AES key is void NL_SetEncryptionKey uint8_T Ekey Once the encryption is enabled by selecting the DEVICE_WM_ENCRYPT_DATA option in the interfaceconfig h file data is encrypted using the AES128 algorithm wi
12. 2 20s Timeout for broadcast frame retransmission 10sec step define DEFAULT_NTW_P_BC_GLOBAL_TX_TO 2 208 Timeout for network inactivity must be gt NTW_P_ACK_RX_TO define DEFAULT_NTW_P_ACTIVITY_TO 20000 7 2S Communication watchdog timeout define DEFAULT_NTW_P_WATCHDOG_TO 6 1min Timeout for completing a datatransfer one way define DEFAULT_NTW_P_DATATRANSFER_TO 10 10s Timeout for band in use 0 no timeout check define DEFAULT_NTW_P_BANDINUSE_TO O 100us step Timeout for sending a frame through SPI define DEFAULT_NTW_P_FRAME_ TX_ TO 12000 1 28 Timeout for repeat a broadcast frame define DEFAULT_NTW_P_BCAST_TX_TO 150000 77 15s Timeout for receiving an ACK 2400bps PLM speed worst case define DEFAULT_NTW_P_ACK RX_TO 2500 250ms Timeout for receiving a bACK 2400bps PLM speed worst case define DEFAULT_NTW_P_bACK_RX_TO 2500 77 250ms Timeout for frame receptions receiver define DEFAULT_NTW_P_FRM_RX_TO O 100us step Minimum delay before any transmission define DEFAULT_NTW_P_NDX_TO 100 10ms Max attempts if no activity is detected define DEFAULT_LL MAX ATTEMPT 5 Max repetition attempts for processed ID 0 disabled Doc ID 023619 Rev 1 15 27 ST7540 stack firmware code UM1573 define DEFAULT_MAX RPT_ATTEMPT 0 2 2 1 Stack initialization The following are the steps needed to configure the sta
13. LM InterruptInitStructure PLM SPI _SubPriority PLM_SPI_INT_SUB_ PRIORITY PLM InterruptInitStructure PLM CDPD PreemptyPriority PLM CDPD PREEMPTY PRIORITY PLM InterruptInitStructure PLM_CDPD_SubPriority PLM_CDPD_ SUB PRIORITY PLM PeripheralInit amp PLM_InterruptiInitStructure The PLM parameters configuration assigning the wanted values is done with the code shown here below In this example PLM is configured with a bandpass filter of 182 5 KHz a data baud rate of 2400 bps deviation of 0 5 and high sensitivity with the prefilter on Please refer to the ST7540 datasheets for more details on PLM parameters Doc ID 023619 Rev 1 ky UM1573 2 1 2 2 1 3 lt ST7540 stack firmware code PLM InitStructure PLM HeaderPreamble HEADER PREAMBLE VALUE PLM InitStructure PLM BandpassFrequency PLM _PB FREQ 132KHz PLM InitStructure PLM BaudRate PLM BAUDRATE_ 2400 PLM TInitStructure PLM Deviation PLM DEVIATION_05 PLM TnitStructure PLM PreFilter PLM PRE FILTER_ON PLM TnitStructure PLM Sensitivity PLM_SENSITIVITY_HIGH In order to load the parameters initialize the PLM variables reset and put the device in IDLE mode the following APIs must be used PLM Init amp PLM InitStructure PLM Reset Receiving data from power line modem The following API enables the PLM to receive data from the power line As soon as a data frame is received before receiving the next data frame the function must be called agai
14. RPTALL LL FRM PARAM DISABLED wm DEVICE OPT GRP LL FRM PARAM DISABLED wm DEVICE OPT ENC LL FRM PARAM DISABLED ACK frames lt 16 27 Doc ID 023619 Rev 1 UM1573 lt ST7540 stack firmware code ifdef DEVICE_WM_REQ_ACK wm DEVICE_OPT_ACK LL_FRM_PARAM_ACK_REQ endif bACK frames ifdef DEVICE_WM_REQ_ ACK wm DEVICE_OPT_bACK LL_FRM_PARAM_ ACK_REQ endif Repetitions ifdef DEVICE_WM_REPEATER wm DEVICE_OPT_RPT LL_FRM_PARAM_REPEAT endif ifdef DEVICE_WM_REPEAT_ALL wm DEVICE_OPT_RPTALL LL_FRM_PARAM_REPEAT_ALL endif Grouping 1fdef DEVICE _WM_GROUP_FILTER wm DEVICE OPT GRP LL FRM PARAM GROUP endif FF BNCFvpreLon 7 1fdef DEVICE_WM_ENCRYPT_DATA wm DEVICE_OPT_ENC LL FRM PARAM ENCRYPTION tendi f return wm Once the initialization structures are loaded the stack is configured with the following code if NL_NetworkInit APP_InitStackWorkingMode APP_InitStackDefaults uint16_t LocalGroup uint32_t LocalAddress Set the current group and address NL_SetLocalAddress LocalGroup LocalAddress The NL_SetLocalAddress API sets the grouping and the address for the device If the grouping is not used the address is made up of both parameters allowing a 6 byte addressing 2 for group and 4 for address At runtime normally at the power on if for example some or all the parameters are stored in the internal Flash memory of the STM32F103xx it is possibl
15. SE IN MILITARY AIR CRAFT SPACE LIFE SAVING OR LIFE SUSTAINING APPLICATIONS NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY DEATH OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ST PRODUCTS WHICH ARE NOT SPECIFIED AS AUTOMOTIVE GRADE MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER S OWN RISK Resale of ST products with provisions different from the statements and or technical features set forth in this document shall immediately void any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever any liability of ST ST and the ST logo are trademarks or registered trademarks of ST in various countries Information in this document supersedes and replaces all information previously supplied The ST logo is a registered trademark of STMicroelectronics All other names are the property of their respective owners 2012 STMicroelectronics All rights reserved STMicroelectronics group of companies Australia Belgium Brazil Canada China Czech Republic Finland France Germany Hong Kong India Israel Italy Japan Malaysia Malta Morocco Philippines Singapore Spain Sweden Switzerland United Kingdom United States of America www st com ky Doc ID 023619 Rev 1 27 27
16. ack link layer is the network layer All the interface API definitions are in the stk_n h file lt Doc ID 023619 Rev 1 UM1573 lt ST7540 stack firmware code The stack engine update is done by using the NL_DeviceStackUpdate function in a non blocking firmware flow void main void Application initialization Infinitive loop while 1 User application state machine USER_ApplicationSMupdate Stack engine update NL_DeviceStackUpdate or using an asynchronous from the program flow interrupt event of a timer or another peripheral or external device RTC for example void main void 1 Application initialization User application code Internal timer task event periodic external event void Timer_InterruptRequest void i Stack engine update NL_DeviceStackUpdate In the interfaceconfig h file all the macros that represent the default configuration for the chosen working model and the stack parameters are defined All the parameters and the configuration can be set in run mode using the appropriate APIs described hereinafter The stack working mode configuration parameters defined in the interfaceconfig h file are shown below In order to disable the corresponding option it is necessary to comment the equivalent macro Doc ID 023619 Rev 1 13 27 ST7540 stack firmware code UM1573 14 27 ee ee E E E E E WORKING
17. ansmission is completed using the following code in this firmware release the value of LL_HDR_SIZE is 19 bytes Send data throughout PL void PLM SendData uint8 _t buffer uint8_t len Wait frame transmission Manage timeout eventually or use this API ina state machine while PLM FrameSent Some other APIs can be used for statistics or for testing the PL performance or any other use and for the ST7540 internal register direct access Get the number of FEC correction for the arrived frame ulint8_t PLM GetFECCorrections void Get the postamble status for the arrived frame PLM_WP_TypeDef PLM GetWrongPostamble void Write a buffer of len bytes in the ST7540 internal registers void PLM WriteRegisters u8 buffer u8 len Enable the ST7540 internal registers reading use the PLM FrameArrived function to test the data arrived flag void PLM StartReadRegisters void Data link and network level The data link layer implements the core of the stack protocol described at the beginning of this section The stack is designed to work in a state machine firmware flow this means that IN awhile 1 loop or in a task routine called by a timer or any other synchronous periodic event of the user application level the stack engine update function must be called in order to update all the events and perform the consequent actions The interface between the user application layer and the st
18. ck in the user application First all the parameters defined in the interfaceconfig h file must be loaded in the stack configuration structures using the LL_WM_t and LL_settings_t data structure defined in the file stk_1 h For this issue two initialization functions can be defined in the user application file LL settings_t APP_InitStackDefaults void LL settings_t ds Typedef defined in the stk_1 h file Link Layer stack default settings ds MIN_SLOT DEFAULT _MIN_ SLOT ds MAX SLOT DEFAULT MAX SLOT ds GLOBAL TX TO DEFAULT_NTW_P_ GLOBAL TX_TO ds BC_GLOBAL TX_TO DEFAULT_NTW_P_BC_ GLOBAL TX_TO ds ACTIVITY_TO DEFAULT_NTW_P_ACTIVITY_TO ds WATCHDOG_TO DEFAULT _NTW_P_WATCHDOG_TO ds DATATRANSFER_TO DEFAULT_NTW_P_DATATRANSFER_TO ds BANDINUSE_TO DEFAULT _NTW_P_BANDINUSE_TO ds FRAME TX _ TO DEFAULT _NTW_P_FRAME TX_TO ds BCAST_TX_TO DEFAULT_NTW_P_BCAST_TX_TO ds ACK_RX_TO DEFAULT_NTW_P_ACK RX_TO ds bACK_RX_TO DEFAULT _NTW_P_bACK RX_TO ds FRM_RX_TO DEFAULT _NTW_P_FRM_RX_TO ds NDX_TO DEFAULT _NTW_P_NDX_TO ds MAX ATTEMPT DEFAULT _ LL MAX ATTEMPT ds MAX RPT_ATTEMPT DEFAULT MAX RPT_ATTEMPT ds TIME SYNC DEFAULT DEVICE _ TIME SYNC return ds LL WM_t APP_InitStackWorkingMode void LL WM_t wm Typedef defined in the stk_1 h file wm DEVICE OPT ACK LL FRM PARAM DISABLED wm DEVICE OPT _bACK LL FRM PARAM DISABLED wm DEVICE OPT RPT LL FRM PARAM DISABLED wm DEVICE OPT
19. e Y ID ALREADY START ADDRESS PROCESSED TOUT ACK amp ACK ID ACK timeout ELAPSED Ma counter STORE NEW ID Frame amp Frame ID ACK SENSED Node x CHECK Frame ID AM15247v1 The current firmware implementation is unique for any kind of device master slave or repeater The PLM stack is able to understand when the master slave or repeater state machine must be executed depending on the data context Figure 5 shows the block diagram of the implemented firmware stack 2 1 ST7540 driver layer The lower firmware layer or level is the physical layer which contains the ST7540 driver and is made up of all the routines used for the transceiver configuration initialization and management and all the necessary STM32F103xx peripherals for configuration and setup For the physical ST7540 interface management SPI and GPIOs connected to the transceiver the STM32F103xx standard library is used Please refer to the library user manual for more details In order to initialize the ST7540 hardware the following API must be used void PLM PeripheraliInit PLM _IntPriorityInitTypeDef PLM PeripInitStruct In PLM_IntPriorityInitTypeDef the interrupt priorities for both the SPI peripheral and the external interrupt used for the carriage detect pin CDPD can be defined 8 27 Doc ID 023619 Rev 1 lt UM1573 lt ST7540 stack firmware code The data structure is the following typedef struct Interrupt priorities
20. e to override some of the parameters set up with the previous function using the following APIs Set the local working mode void NL_SetLocalWorkingMode uint8_t WorkingMode where the meaning of each bit of the workingMode byte is explained in Figure 7 Doc ID 023619 Rev 1 17 27 ST7540 stack firmware code UM1573 2 2 2 18 27 Figure 7 Stack working mode bitmap definition WorkingMode b7 b6 b5 b4 b3 b2 b1 bO L 1 Frame sent in broadcast 0 unicast 1 ACK frame requested 0 ACK frame not requested 1 bACK frame requested 0 bACK frame not requested 1 Repetition enabled 0 Repetition disabled 1 Repeat all 0 Repeat after ACK timeout 1 Grouping filter enabled 0 Grouping filter disabled 1 Encrypted data 0 Clear data 0 Reserved AM15249v1 Set the local hop level void NL_SetLocalHopLevel uint8_t HopLevel Set the stack parameters typedef defined in stk_n h file void NL SetDataLinkStackParameters NL_DLSP_t devparam Stack data reception service NL_NetworkIndication The service used for receiving data from the network is defined in the stk_n h file which is the interface between the ST7540 stack and the user application level NL_Status_t nNStatus NL NetworkIndication NL_ _Data_t ntw data uint32_t timeout The value returned in the nNStatus variable can be one of the values defined in the NL Status_t structure defined in the file stk_n h if nNStatus
21. eady taken This repetition mechanism managed directly by the PLM stack engine is done once per node until either the data frame is acknowledged or each node has repeated the data frame The repetition mechanism is also implemented for the acknowledgement frame when not received by the master Figure 4 Data communication flow with a case of repetition q ees es Tr ese NOT SENSED ACK bACK a lt As each firmware layer adds its own information to the original frame 100 bytes of user data from the application level become more than double that at the power line level This is mainly because of the FEC redundancy added to each byte as soon as it arrives at a target node Network traffic is therefore reduced if the power line is not overly noisy because the FEC algorithm can adjust the corrupted information AM15246v1 Each frame also contains the target address the source address and other parameters These may include a flag byte indicating the network model the flag indicates if the repetition must be ignored for this frame or if the acknowledge is awaited a frame ID to avoid multiple repetitions of the same frame the CRC CRC16 bytes the modem preamble the header and the postamble byte Another implemented mechanism related to repetitions is hopping The hop level is one of the user defined PLM parameters and is employed to assign a certain hierarchy in the repetition If a frame must be repeated but
22. ency set to 60 KHz define PLM FREQ 66KHZ PLM comm frequency set to 66 KHz define PLM _ FREQ 72KHZ PLM comm frequency set to 72 KHz define PLM _ FREQ _76KHZ PLM comm frequency set to 76 KHz define PLM FREQ 82KHZ PLM comm frequency set to 82 05 KHz define PLM _ FREQ 86KHZ PLM comm frequency set to 86 KHz define PLM _ FREQ 110KHZ PLM comm frequency set to 110 KHz define PLM FREQ 132KHZ PLM comm frequency set to 132 6 KHz PLM interface communication baudrate Doc ID 023619 Rev 1 lt UM1573 lt ST7540 stack firmware code define PLM_600_BPS PLM communication baudrate 600 bps define PLM_1200_BPS PLM communication baudrate 1200 bps define PLM _2400_BPS PLM communication baudrate 2400 bps define PLM_4800_BPS PLM communication baudrate 4800 bps PLM Sensitivity define PLM SENS HIGH High sensitivity define PLM _SENS_ NORMAL Normal sensitivity The stack parameters defined in the interfaceconfig h file are explained here below eae aera ee ee ee eee eee ee re re ee DEFAULT LINK LAYER STACK DATA VALUES lt gt MODIFY WITH CARE Pee ei ema eee eee eee eh eee oe Minimum time slot for the back off time define DEFAULT MIN SLOT 5 300 us Maximum time slot for the back off time define DEFAULT MAX SLOT 500 50 ms Timeout for complete the communication 20sec 10sec step define DEFAULT _NTW_P GLOBAL TX _TO
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24. n void PLM StartReceiveData void The next instruction notifies when a data frame has arrived and is ready to be read if PLM FrameArrived Another instruction can be used instead to test if a data frame is ready in the PLM buffer and if this is the case it automatically removes the header and the redundancy FEC and checks if the data frame has a correct postamble The data reception is automatically enabled by this API if the frame is rejected if PLM ValidFrameArrived If valid data has arrived the data length and the received data buffer are recovered by the following APIs Recover received data frame length uint8_t plm_len PLM GetBufferLength Points to PLM data buffer uint8_t plm_buffer PLM GetReceivedBufferPointer Transmitting data to power line modem Before transmitting data the user should check if the band is already in use this can happen if another device is transmitting data and the PLM detects a header sequence if PLM BandInUse i Doc ID 023619 Rev 1 11 27 ST7540 stack firmware code UM1573 2 2 12 27 The buffer is then filled with the data to send and the correct buffer length is set Max payload size is 100 bytes Do not exceeds this value uint8_t buffer PAYLOAD_SIZE LL_HDR_SIZE ulnt8_t len LL _HDR_SIZE Is the size of some extra bytes added by the upper levels when a stack is used Send the user bytes and wait until the tr
25. oadcast belonging to this group and correctly acknowledged by the sender All of this is transparent to the user as it is automatically managed by the stack The fields data buffer and framelen contain the user raw data and the data length Refer to the stk_n h file for the admitted frame types If a data reception error occurs this can be verified checking the value of the field error of the NL_Status_t structure nNStatus error The following enumerations are the possible communication errors including also the transmission errors and are reported in the stk_n h file typedef enum NL_ERR_NONE No error NL_ERR_NOT_READY Stack not initialized NL_ERR_NETWORK_TIMEOUT Given timeout elapsed NL_ERR_TRANSMISSION_ERROR Data transmission error NL_ERR_COMMUNICATION_TIMEOUT Communication timeout NL_ERR_ LINE _ERROR Power line error NL_ERR_TARGET NOT_REACHABLE Target device unreachable NL ERR FRAME CLASS UNKNOWN Unknown frame type NL_ERR_GENERIC Unclassified error Doc ID 023619 Rev 1 19 27 ST7540 stack firmware code UM1573 2 2 3 20 27 NL ERR Stack data transmission service NL_NetworkRequest The service used for transmitting data from the network is also defined in the stk_n h file NL_Status_t nNStatus NL NetworkReguest NL_Data_t ntw_ data uint32_t timeout In order to transmit user data first the NL_Data_t structure must be filled NL Data_t user data uint8_ t i user_data group
26. operation N_DOING PL IDLE MODE User application while no data is arrived from PLM else if nNStatus operation N_ERROR PL DATA RECEPTION ERROR Error Management else if nNStatus operation N_SUCCESS PL DATA ARRIVED lt Doc ID 023619 Rev 1 UM1573 lt ST7540 stack firmware code Valid data arrived from PIM and addressed to this device or sent in broadcast by a remote PLM broadcast frame are sent with LL_BROADCAST_FLAG set in the ntw_data frametype field When valid data arrive from the power line data can be recovered from the structure NL_Data_t in this example pointed by ntw_data pointer typedef struct uintl6_t group Sender group uint32_t address Sender address uint8_ t framelen Arrived frame length NL_Type_t frametype Arrived frame type Ue ec databuffer PAYLOAD_SIZE Arrived user data NL_Data_t The group field is the same as this device if the grouping option is enabled because by enabling the group filter all the frames coming from a different group are ignored even those sent in broadcast When the variable nNStatus operation value is N_SUCCESS the data are valid meaning with a correct preamble a correct CRC CRC16 is automatically inserted by the stack during the transmission and checked and then removed during the reception with one of the admitted frame types addressed to this device or sent in br
27. th the supplied AES key Ekey and if the target device has the encryption enabled too and also has the same key the data is correctly decoded directly by the stack If the encryption is not enabled or the key is different the data frame is discharged and consequently not acknowledged Finally it is possible to know the stack firmware release two bytes in the x y decimal format calling the API Stack firmware release x y uint16_t NL GetStackFirmwareRelease void lt Doc ID 023619 Rev 1 UM1573 3 lt Stack firmware structure Stack firmware structure The stack firmware structure contained inside the zip file supplied with this user manual is shown in Figure 8 Inside the root there is the interfaceconfig h file which contains all the macros used for the stack configuration and option setup The src directory contains all the source files and the object files the object files refer to the AES128 0 stk_1 o andstk_n o files The stk_p c and the ST7540 driver contain the source code allowing the user to make modifications eventually required by the chosen microcontroller Figure 8 Stack firmware structure PLMstack45 h interfaceconfig h inc h AES128 h h stk_I h h stk_n h AES128 0 stk_1 0 ST7540 Driver stk_n o AM15250v1 The inc directory contains all the definition files to include in the user project Table 1 shows the stack firmware weight in terms of memory both Flash and RAM
28. the hop level is lower than the one stored in the stack parameter the frame is not forwarded Normally the hierarchy is set depending on the distance and the ambient noise condition The closer the repetition enabled node is to the concentrator the higher the hop level and in this way the traffic of insignificant repetitions is reduced Network grouping is another feature that can be implemented by the user If implemented the first two bytes of any frame address which is 6 bytes long are considered the group address Each frame with a group address different from the assigned group is ignored In this way it is possible that more than one network can share the same power line without interacting with each other Doc ID 023619 Rev 1 7 27 ST7540 stack firmware code UM1573 Figure 5 Firmware stack block diagram Node Y ACK ADDRESS CHECK SENSED Address PENDING Node X n TOUT NOT ID ADDRESS ACK ELAPSED pri SENT SENSED CHECK pending Node x Frame ID Frame ID BACK PENDING ID NOT SENSED START PENDING ID Global timeout counter FRAME SENT Node x REQUEST TO bACK SEND FRAME pa SO Node x TOUT SENSED CHECK ELAPSED NOT i PENDING ID Frame ID Node x SENT f TOUT ELAPSED START PENDING ID bACK timeout BAND IN counter an USE SENSED FRAME SENT SENSED BAND FREE TOUT NOT ELAPSED Node x Node x CHECK Node X TOUT ELAPSED CHECK Frame ADDRESS BAND FREE BAND ADDRESS TOUT NOT A bACK Node x SENSED Node x STORE Nod
29. ware feature of the PLM to avoid transmission conflicts Before initiating any communication each device waits until the band is free by checking its own BU flag As soon as the band is free a random backoff time is calculated Once the backoff time has elapsed if the band is still free the transmission is started otherwise the loop is started again waiting for the BU and new backoff calculation Doc ID 023619 Rev 1 ATI UM1573 lt Network model description The data exchange between all the nodes connected to the same power line also uses a data frame acknowledgement mechanism In this way the master knows if its own transmitted data packet has been correctly delivered to the target node since it receives an acknowledgment frame for each data frame sent to a target device This acknowledgement excludes some data frames sent in broadcast by the master Figure 2 Data exchange diagram DATATO tO SLAVEx t SENDACK FRAME Receive UserData SENDDATA ti FRAME Data Processing SEND bACK t3 FRAME AM15244v1 The repetition feature improves the probability that the data frame is delivered to nodes that are far away or under noisy network environments As all the other nodes are connected in the same power line they continuously sense the network catching all data transiting on it Depending on the device addressing and the data frame acknowledge flow each node is able to detect if the sensed frame must be repeated
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