AN10404 Initialization code/hints for the LPC2000 family
Contents
1. Software Tool Support ona FWD Additional Resources 2 Initialization guidelines AN10404_1 Most ARM applications begin by executing an assembly startup file This file could be linked to the bottom of the on chip memory Flash 0x0 or SRAM 0x400 0000 or Bank 0 for devices with an external memory interface depending from where the application is targeted to run The following should be covered in this startup file 1 Interrupt Vector table 2 Stack pointers 3 Branch to Main After the above basic assembly initialization code is executed a branch is done to C main The following steps could be carried out in C code 1 Enable the Memory Accelerator Module MAM if the application is run from on chip Flash It provides accelerated execution at higher frequencies and also helps in reducing power consumption The MAM is only available in devices with on chip Flash 2 Set the System clock and peripheral clock The system clock can be boosted using the PLL to 60 MHz or 75 MHz for LPC2220 depending upon the input frequency The peripheral clock can be set using the VPB Divider register VPBDIV at address OxE01F C100 Please refer to Application note AN10331 to get detailed information about the PLL 3 Set the Memory Mapping Control register MEMMAP at address 0xE01F C040 accordingly The MEMMAP register gives the application the flexibility of executing interrupts from different memory regions For instance if ME2. N V 2005 All rights reserved Application note Rev 01 1 November 2005 5 of 15 Philips Semiconductors AN1 0404 Initialization code hints for the LPC2000 family W Tera Term COM2 T Fig 2 Tera Term interface settings 3 2 Philips ISP utility To avoid the trouble of interfacing the device each time using the above process Philips provides a Visual Basic Application which is free for download at the Philips website For more information on using this utility please refer to the application note AN10302 Using the Philips LPC2000 Flash Utility with the Keil MCB2100 and the IAR LPC210x kickstart evaluation boards available online LPC2000 Flash Utility iol xi Ble Buffer Help PHILIPS LPC2000 Flash Utility V2 2 2 Flash Progamming p Erase Blank Communication Filename ooo MM Fc S E Execute Code Upload to Flash at Upsi 3 Stat Sectee 14 3600 be rase Compare Flash Harsia Reset EndSecto 14 TimeOut sec 1 Device 7 se OTA ATS Device LPC2138 Read Patin civic TAL Freg kHz 12000 evice ID Boot Loader ID ee Fig 3 LPC2000 Flash Utility screenshot AN10404_1 Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 6 of 15 Philips Semiconductors AN1 0404 Initialization code hints for the LPC2000 family 3 3 Bootloader version 3 4 Certain devices in th
3. needed In this case code is still constantly fetched from the on chip Flash and executed which adds to the power consumption A better solution would be to switch to the Idle power saving mode and then wait for interrupts An interrupt from a peripheral would then wake the device from Idle mode Considerable power savings can be achieved by keeping the ARM7 core in Idle mode while it is waiting for interrupts As mentioned above Flash fetches adds to power consumption If the program is encoded using the Thumb instruction set then with each Flash fetch eight instructions are fetched instead of four as compared to ARM Thus the number of Flash fetches could be reduced by using Thumb code To reduce current consumption on the 3 3 V rail in power down mode let s consider the 144 pin devices a There are 80 pins with internal pull ups on Ports 1 2 and 3 These pull ups are always active b Set those pins high or keep them floating before entering power down mode If set low they will consume around 50 pA typical on each pin c Port 0 does not have any internal pull ups These pins can be set low Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 7 of 15 Philips Semiconductors AN1 0404 Initialization code hints for the LPC2000 family d In LPC2114 2124 221 2 221 4 2119 2129 2194 2290 2292 2294 and 2210 there is leakage current around 200 uA
4. that are described herein for any of these products are for illustrative purposes only Philips Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or modification 9 Trademarks Notice All referenced brands product names service names and trademarks are the property of their respective owners Koninklijke Philips Electronics N V 2005 All rights reserved 14 of 15 AN10404_1 Application note Rev 01 1 November 2005 Philips Semiconductors AN1 0404 i Initialization code hints for the LPC2000 family 10 Contents 1 Introduction 000 cee eee eee 3 2 Initialization guidelines 3 3 Notes on the On Chip Bootloader 4 3 1 Communicating with the Bootloader via Tera Term Pro HyperTerminal 0 005 4 3 2 Philips ISP utility 0 05 6 3 3 Bootloader version 20 005 7 3 4 Code Read Protection CRP 7 4 Reducing power consumption 7 5 Code example 0 00e cece eee e eee 8 5 1 Startup assembly code 8 5 1 1 Interrupt vector table 8 5 1 2 Setting up Stack Pointers and Enabling INTE FFUPTS 0 2 pods ae pace ee ie ade Kedar E 9 5 2 CCOdE ks E E EE 10 6 Software Tool Support 02005 11 6 1 KG ill aoe aoa Sits meane a oa 11 6 1 1 GUI for Startup code 0 0004 1
5. this startup file in addition to configuring the stack they also provide the ability to configure the PLL and the MAM configuration window B C KEIL23a ARM Boards Keil MCB2100 Blinky Startup s Expand All Collapse All Help value El Stack Configuration Stack Sizes in Bytes Undefined Mode 0x0000 0004 Supervisor Mode 0x0000 0004 Abort Mode ox0000 0004 i Fast Interrupt Mode 0x0000 0004 i Interrupt Mode 0x0000 0080 i User System Mode 0x0000 0400 PLL Setup v MSEL PLL Multiplier Selection 5 PSEL PLL Divider Selection 2 BEMAM Setup Iv i MAM Control Fully Enabled 1 MAM Timing 4 Text Editor Configuration Wizard j Fig 4 Keil assembly startup file configuration 6 1 2 Simulator Mode Keil has implemented most of the LPC2000 peripherals in their Simulator Its easy to use and also provides easy debugging of the software before running on the target hardware itself Below is a screenshot of their GPIO simulation Similar simulations can be found for other peripherals The simulator also provides a Logic Analyzer and a serial window AN10404_1 Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 11 of 15 Philips Semiconductors AN1 0404 a Initialization code hints for the LPC2000 family General Purpose Input Output 1 GPIO 1 E E ae D 00FFO000 31 Bits 24 fj 5 Bie e 15 Bits Ber Bits 0 1OSET1 ox00200000 PPT
6. 1 6 1 2 Simulator Mode 20 00055 11 6 2 IAR Systems 0 0 eee eee ee 12 6 2 1 IAR MakeApp 20000 eee eee 12 6 2 2 IAR visualSTATE 020000 13 6 3 Hitex Development Tools 14 7 Additional Resources 15 8 Disclaimers 2 322 36022 tierce nse dmeue 17 9 Trademarks 0 200 e eee eee eee 17 Koninklijke Philips Electronics N V 2005 All rights are reserved Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner The information presented in this document does not form part of any quotation or contract is believed to be accurate and reliable and may PHILIPS be changed without notice No liability will be accepted by the publisher for any consequence of its use Publication thereof does not convey nor imply any license under patent or other industrial or intellectual property rights Date of release 1 November 2005 Document number AN10404_1 Published in The Netherlands
7. AN10404 Initialization code hints for the LPC2000 family wee Rev 01 1 November 2005 Application note m Document information Info Content Keywords ARM assembly code Initialization Clock Stack power consumption Abstract Provides initialization steps hints for reducing power consumption and code examples that would get the LPC2000 device ready for the target application PHILIPS Philips Semiconductors AN1 0404 ai Initialization code hints for the LPC2000 family Revision history Rev Date Description 01 20051101 Initial version Contact information For additional information please visit http www semiconductors philips com For sales office addresses please send an email to sales addresses www semiconductors philips com AN10404_1 Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 2 of 15 Philips Semiconductors AN1 0404 Initialization code hints for the LPC2000 family 1 Introduction This application note provides guidelines that have to be taken into consideration while writing your software application for the LPC2000 family Effort has been done to cover most of the issues that could affect certain aspects of the end application The application note has been divided into the following sections Initialization guidelines Notes on the On chip Bootloader Reducing power consumption Code examples
8. MAMTIM value would depend upon the system clock desired MAM is fully enabled below MAMTIM 0x MAMCR 0x2 Setup the system clock to the desired clock frequency The PLLCFG value is provided for input frequency of 12 MHz and the desired system frequency is 60 MHz PLLCFG 0x24 feed Enabling the PLL PLLCON 0x1 feed Wait for the PLL to lock to set frequency while PLLSTAT amp PLOCK Connect the PLL as the clock source PLLCON 0x3 feed Set the peripheral clock Here we set it to 60 MHz VPBDIV 0x1 This would now be followed by the user code depending upon the application and guidelines mentioned above While 1 Feed sequence for the PLL void feed PLLFEED 0xAA PLLFEED 0x55 Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 10 of 15 Philips Semiconductors AN1 0404 a Initialization code hints for the LPC2000 family 6 Software Tool Support We have support from several software tool vendors for our LPC2000 family In this application note we have taken some key features that are provided by Keil and IAR Systems Also listed below is The Insiders guide to the Philips ARM7 Based Microcontrollers from Hitex Development tools 6 1 Keil 6 1 1 GUI for Startup code Keil has made it extremely easy to configure the Assembly Startup file by providing a GUI In
9. MAP is set to 0x2 the interrupt vectors would be mapped to 0x4000 0000 bottom of on chip SRAM 4 Disable unused peripherals using the Power Control for Peripherals register PCONP at address 0xE01F COC4 5 Configure GPIO s using the respective IODIR IOSET and IOCLR registers On the LPC2000 there are certain pins that should not be held low on reset For instance by driving P0 14 low on reset would make the on chip bootloader to take control of the part after reset Please refer to the Flash Memory System and Programming Chapter Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 3 of 15 Philips Semiconductors AN1 0404 i Initialization code hints for the LPC2000 family in the User Manual for detailed information There could also be an additional pin in certain devices which should not be held low on reset If low on reset then the device behavior is not guaranteed The following are the pins in various devices a In LPC213x and LPC214x devices P0 31 should not held low on reset b In LPC2114 2124 221 2 221 4 2119 2129 2194 2290 2292 2294 2210 and 2220 devices P0 26 should not be held low on reset 6 Depending upon the peripherals being used set the port functions accordingly using the appropriate Pin Function Select register PINSELx 7 Initialize the peripherals which are still enabled in PCONP and enable interrupts for them if needed 8 Con
10. e LPC2000 family need to have the latest bootloader versions LPC2114 21 24 221 2 221 4 2119 2129 2194 2290 2292 2294 and 2210 need to have bootloader version 1 63 or higher LPC2104 5 6 needs to have version 1 52 or higher A field update package is available online at our website and it is named LPC2000 Bootloader update via ISP Code Read Protection CRP CRP can be enabled by programming the flash address location 0x1FC with value 0x87654321 2271560481 decimal More details on CRP can be found in the Flash Memory System and Programming Chapter in the respective User Manual CRP is not available with the LPC2104 5 6 4 Reducing power consumption AN10404_1 Below are some hints which will reduce power consumption 1 All the LPC2000 devices have two power saving modes Idle and Power down Please refer to the Power Control section in the System Control Block chapter in the User Manual Enable the MAM if the application is run from the on chip Flash Enabling the MAM will enable various buffers and reduces the number of Flash fetches thereby reducing power consumption Disable unused peripherals using the PCONP register 4 The peripherals can run at a lower speed as compared to the ARM7 core frequency Using the VPBDIV register the peripherals can run at either half or one fourth of the system frequency Most embedded applications terminate with a while 1 loop and they service interrupts whenever
11. figure the Vectored Interrupt Controller VIC to handle the different interrupt sources and classify them as IRQ and FIQ It is recommended that only one interrupt source should be classified as an FIQ For more detailed information on Interrupt handling please refer to Application notes AN10254 Handling Interrupts using IRQ and FIQ and AN10381 Nesting of interrupts in the LPC2000 9 It is always safe to program the Default Vector Address Register VICDefVectAddr at address OxFFFF F034 with a dummy ISR address wherein the VIC would be updated by performing a write operation on the VIC Vector Address register VICVectAdar at address OxFFFF F030 to avoid any spurious interrupts 3 Notes on the On Chip Bootloader 3 1 Communicating with the Bootloader via Tera Term Pro HyperTerminal Communicating with the bootloader via the Serial port is a fairly easy task and can be done in multiple ways Considering the evaluation board on which the LPC2000 device is mounted has a RS 232 connector interfaced to UARTO a PC Terminal program for instance Tera Term Pro or Hyperterminal can talk to the device by issuing various In System Programming ISP commands as mentioned above to enter this mode P0 14 would be held low on reset More information on ISP can be found at the Flash Memory System and Programming Chapter in the respective device User Manual Please follow the below steps to communicate with the LPC2000 on chip bootloader throug
12. h UARTO using Tera Term Pro Tera Term Pro settings would be as follows AN10404_1 Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 4 of 15 Philips Semiconductors AN1 0404 H Initialization code hints for the LPC2000 family Port comi gt OK Baud rate s600 gt Data abt z Cancel Parity none gt Stop ibt gt Help Flow control none gt Transmit delay fo msecjchar fo msecjline Fig 1 Tera Term serial port settings Follow the below steps to communicate with the bootloader 1 Send synchronization character Ox3F and wait for a response 2 The LPC2000 device would return with the ASCII string Synchronized lt CR gt lt LF gt 3 Reply back with the same ASCII string Synchronized lt CR gt lt LF gt The bootloader is case sensitive 4 The device would reply back with OK lt CR gt lt LF gt 5 Send the crystal frequency in KHz at which the part is running For instance if the crystal frequency is 12 MHz then send 12000 The part is now initialized and the ISP command handler is invoked 6 The host machine can now issue ISP commands An Unlock command U 21130 lt CR gt lt LF gt is needed to execute Flash Write Erase and Go commands A snapshot from Tera Term Pro been interfaced to the LPC2148 is shown below AN10404_1 Koninklijke Philips Electronics
13. he ARM website AN10404_1 Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 13 of 15 Philips Semiconductors AN10404 8 Disclaimers Life support These products are not designed for use in life support appliances devices or systems where malfunction of these products can reasonably be expected to result in personal injury Philips Semiconductors customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application Right to make changes Philips Semiconductors reserves the right to make changes in the products including circuits standard cells and or software described or contained herein in order to improve design and or performance When the product is in full production status Production relevant changes will be communicated via a Customer Product Process Change Notification CPCN Philips Semiconductors assumes no responsibility or liability for the use of any of these products conveys no licence or title under any patent copyright or mask work right to these Initialization code hints for the LPC2000 family products and makes no representations or warranties that these products are free from patent copyright or mask work right infringement unless otherwise specified Application information Applications
14. ilips ARM7 Based Microcontrollers This book is free for download at both the Philips and Hitex websites and provides useful information regarding our devices The Insider s Guide can be used as the basis of a self teaching course when used with the Keil uVISION3 compiler IDE All the examples included with the Guide can be built for either the simulator or the MCB2100 evaluation board For more information please visit the Hitex Development Tools website AN10404_1 Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 12 of 15 Philips Semiconductors AN1 0404 E Initialization code hints for the LPC2000 family TOITIS THE INSIDER S GUIDE TO THE PHILIPS ARM7 BASED MICROCONTROLLERS An Engineer s introduction To The LPC2100 Series Trevor Martin BSc hons CEng MIEE www hitex co uk arm Fig 6 Covershot of hitex programmer s guide 7 Additional Resources 1 Philips Semiconductors website which allows access to Philips support 2 LPC2000 Yahoo forum Founded on November 17th 2003 this Yahoo forum is dedicated to the LPC2000 Family It has over 2000 members and provides the best online support Be sure to refer to the Files section of this group for sample board schematics software etc 3 ARMTDMI S Technical Reference Manual The LPC2000 family is based on the ARM7TDMI S core The technical reference manual is free for download on t
15. ility have this feature built in so the end user need not worry about it If the tool does not provide this feature then the value has to be computed manually and has to be inserted at 0x14 Details on computation of checksum could be found in the Flash programming chapter in the device User Manual DCD The below instruction is the IRQ vector and it will load the PC with the ISR of the highest priorty interrupt from the VIC Vector Address Register VICVectAddr at address OxFFFFF030 LDR PC PC 0xFF0 The ISR for FIQ can start from the below address itself LDR PC FIQ_Addr Undefined_Addr DCD Undefined_Handler SWI_Addr DCD SWI_Handler Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 8 of 15 Philips Semiconductors AN10404 AN10404_1 5 1 2 Initialization code hints for the LPC2000 family Prefetch_Addr DCD Prefetch_Handler Abort_Addr DCD Abort_Handler FIQ_ Addr DCD FIQ_Handler Exception Handlers The following dummy handlers do not do anything useful in this example They are set up here for completeness Undefined_Handler B Undefined_Handler SWI_Handler B SWI_Handler Prefetch_Handler B Prefetch_Handler Abort_Handler B Abort_Handler FIQ_ Handler B FIQ_Handler END On reset the first instruction to be executed would be LDR PC Reset_Addr Once this instruction is executed a jump is done t
16. o Reset_Addr From here the interrupts need to be enabled and the stack pointers for the various modes need to be set before jumping to C main Setting up Stack Pointers and Enabling Interrupts While setting the stack pointer please note that the Flash programming routines use a section of the on chip SRAM In System Programming ISP uses the top 256 bytes and In Application Programming IAP uses the top 128 bytes of the on chip SRAM The application stack should not overlap this area Enabling interrupts in the CPSR and keeping the part sor mode after ARM7 core reset 0x13 in Supervi MSR cpsr_c Setting up SP for Supervisor Mode LDR SP 0x4 Setting up the SP for various modes can be done in several ways Below is the sample code for setting the SP for IRQ mode SP_irq After setting the SP_irg the mode is switched back to Supervisor Mode MRS RO CPSR BIC R1 RO 0x1F ORR R1 R1 0x12 MSR cpsr_c R1 LDR SP 0x4 MSR RO cpsr_c Koninklijke Philips Electronics N V 2005 All rights reserved Application note Rev 01 1 November 2005 9 of 15 Philips Semiconductors AN1 0404 AN10404_1 Initialization code hints for the LPC2000 family Please note that incorrect setting of the SP can cause the ARM7 core to cause a Data Abort After setting the stack pointers the program counter would be ready to be linked to C main C code int main The
17. on External Interrupt ADC pins if these pins are pulled higher than 1 8 V External Interrupt pins will contribute to the leakage irrespective of the pin configuration ADC pins will contribute to the leakage only if they are configured as analog inputs 8 On a side note since the on chip SRAM controller incorporates a write back buffer which holds the last data sent by software to the SRAM a dummy write needs to be done before entering idle or power down mode to avoid losing the data after a subsequent reset Hence it is a good practice to write to a variable twice before entering either power saving mode Please refer to section On Chip Static RAM SRAM in Chapter 1 of the respective User Manual for more detailed information 5 Code example AN10404_1 5 1 5 1 1 Startup assembly code Interrupt vector table In this code section the interrupt vectors are set up for the ARM core It would be linked to the bottom of the memory If running from external memory this code will be run from Bank0 Comments in the code below are preceded by This might vary depending upon the Assembler being used LDR PC Reset_Addr LDR PC Undefined_Addr LDR PC SWI_Addr LDR PC Prefetch_Addr LDR PC Abort_Addr At 0x14 the user should insert a signature checksum This signature enables the bootloader to determine if there is valid user code in the Flash Currently most of the Flash programming tools even the Philips ISP ut
18. r er rre arrr WOCLAY oxo0000000 Freer rrr arrar IOPIN1 OsFF200000 RPP MET Pe cee Pins OxFF200000 ViViVivivivivid TWP Teo Fig 5 GPIO simulation screenshot 6 2 IAR Systems IAR provides their startup code so that the end user gets a jump start into their application by starting to code to C itself The startup code usually named as lpc2xxx_cstartup s79 can be found with the example projects that accompany the software 6 2 1 IAR MakeApp IAR MakeApp provides a highly visual workspace for the configuration for certain LPC2000 devices in 48 64 and 144 pin packages Device driver code is created automatically and the application software gets instant access to the peripherals of the microcontroller This tool is available for free download at the MakeApp website 6 2 2 IAR visualSTATE visualSTATE is a suite of graphical design automation tools for embedded systems An embedded system can be designed using a flowchart model Extensive testing can be performed which includes validation of the application behavior regression testing and simulation on chip Finally it can create micro tight C C code which is consistent with the design specifications coupled with a complete design documentation 6 3 Hitex Development Tools Hitex Development Tools support the LPC2000 family with their toolchain In addition to this support they have also prepared a very resourceful book called The Insiders guide to the Ph
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