LPC1769 Integration

jwschmo wrote on Wednesday, October 26, 2016:


I’ve been working to get FreeRTOS integrated with some code on an LPC1769 that is using open source compilers etc and some serious legacy code. Its an odd project where a good chunk of the code is in .CPP files however, its not class based function calls. so with that in mind I started to integrate freertos in, and I’m getting stuck. Now I know that the right way to do this is integrate everything based on the example project, however, I’ve inherited a significant code base that would be really cumbersome to rewrite for the example project.

SO - I was wondering the following - I have successfully demonstrated to myself that the rtos function call “vTaskStartScheduler” is successfully executing all the way to the assembly code in port.c:

static void prvPortStartFirstTask( void )
__asm volatile(
" ldr r0, =0xE000ED08 \n" /* Use the NVIC offset register to locate the stack. /
" ldr r0, [r0] \n"
" ldr r0, [r0] \n"
" msr msp, r0 \n" /
Set the msp back to the start of the stack. /
" cpsie i \n" /
Globally enable interrupts. /
" cpsie f \n"
" dsb \n"
" isb \n"
" svc 0 \n" /
System call to start first task. */
" nop \n"

because some Red LED shows up on the board. HOWEVER! after that is called the Task that I’m expecting to start working doesn’t crop up. It looks something like this in main.cpp:

extern “C”{

static void someLoopTask( void *pvParameters );


#ifndef TEST_MODE
int main(void) {

xTaskCreate(&someLoopTask,					/* The function that implements the task. */
			"FwLp", 						/* The text name assigned to the task - for debug only as it is not used by the kernel. */
			configMINIMAL_STACK_SIZE+1000, 		/* The size of the stack to allocate to the task. */
			( void * ) NULL, 				/* The parameter passed to the task - just to check the functionality. */
			mainSIG_TASK_PRIORITY, 			/* The priority assigned to the task. */
			NULL );							/* The task handle is not required, so NULL is passed. */

/* Start the tasks and timer running. */	


for (;;) {

return 0;


extern “C” {

static void someLoopTask( void pvParameters )
Remove compiler warning in the case that configASSERT() is not
defined. */
( void ) pvParameters;

/* Check the task parameter is as expected. */
//configASSERT( ( ( unsigned long ) pvParameters ) == NULL );
for( ;; )



I’ve tried a number of iterations - I’ve looked through the memory mapping (they are different but not incredibly so). I’ve looked through the support files (I’ve copied over the pertenant ones). I’ve played around with the configMINIMAL_STACK_SIZE constant, I’ve played around with the extern “C” locationing, and I’ve played around with the FreeRTOSConfig.h file:

FreeRTOS V9.0.0 - Copyright © 2016 Real Time Engineers Ltd.
All rights reserved


This file is part of the FreeRTOS distribution.

FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation >>>> AND MODIFIED BY <<<< the FreeRTOS exception.

>>!   NOTE: The modification to the GPL is included to allow you to     !<<
>>!   distribute a combined work that includes FreeRTOS without being   !<<
>>!   obliged to provide the source code for proprietary components     !<<
>>!   outside of the FreeRTOS kernel.                                   !<<

FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  Full license text is available on the following
link: http://www.freertos.org/a00114.html

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1 tab == 4 spaces!



The following #error directive is to remind users that a batch file must be
executed prior to this project being built. The batch file cannot be
executed from within the IDE! Once it has been executed, re-open or refresh
the Eclipse project and remove the #error line below.
//#error Ensure CreateProjectDirectoryStructure.bat has been executed before building. See comment immediately above.

#include "LPC17xx.h"

Application specific definitions.

These definitions should be adjusted for your particular hardware and
application requirements.


#define configUSEPREEMPTION 1
#define configUSEIDLEHOOK 0
#define configMAXPRIORITIES ( 5 )
#define configUSETICKHOOK 0
#define configCPUCLOCKHZ ( ( unsigned long ) 100000000 )
#define configTICKRATEHZ ( ( TickTypet ) 1000 )
#define configMINIMALSTACKSIZE ( ( unsigned short ) 80 )
**#define configTOTALHEAPSIZE ( ( sizet ) ( 4 1024 ) )//19
#define configMAXTASKNAMELEN ( 12 )
#define configUSETRACEFACILITY 1
#define configUSE16BITTICKS 0
#define configIDLESHOULDYIELD 0
#define configUSECOROUTINES 0
#define configUSEMUTEXES 1



/ Set the following definitions to 1 to include the API function, or zero
to exclude the API function. /

#define INCLUDEvTaskPrioritySet 1
#define INCLUDEuxTaskPriorityGet 1
#define INCLUDEvTaskDelete 1
#define INCLUDEvTaskCleanUpResources 0
#define INCLUDEvTaskSuspend 1
**#define INCLUDEvTaskDelayUntil 1
#define INCLUDEvTaskDelay 1
#define INCLUDEuxTaskGetStackHighWaterMark 0

/ This demo makes use of one or more example stats formatting functions. These
format the raw data provided by the uxTaskGetSystemState() function in to human
readable ASCII form. See the notes in the implementation of vTaskList() within
FreeRTOS/Source/tasks.c for limitations. /

Ethernet configuration.

/ MAC address configuration. /
**#define configMACADDR0 0x00
**#define configMACADDR1 0x12
**#define configMACADDR2 0x13
**#define configMACADDR3 0x10
**#define configMACADDR4 0x15
#define configMACADDR5 0x11

/ IP address configuration. /
**#define configIPADDR0 192
#define configIPADDR1 168
**#define configIPADDR2 0
#define configIPADDR3 201

/ Netmask configuration. /
**#define configNETMASK0 255
**#define configNETMASK1 255
**#define configNETMASK2 255
#define configNETMASK3 0

/ Use the system definition, if there is one /
#define configPRIOBITS 5 / 32 priority levels /

/ The lowest priority. /
#define configKERNELINTERRUPTPRIORITY ( 31 << (8 - configPRIOBITS) )
/ Priority 5, or 160 as only the top three bits are implemented. /
/ !!! configMAXSYSCALLINTERRUPTPRIORITY must not be set to zero !!!
See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html. /
#define configMAXSYSCALLINTERRUPTPRIORITY ( 5 << (8 - configPRIOBITS) )

/ Priorities passed to NVICSetPriority() do not require shifting as the
function does the shifting itself. Note these priorities need to be equal to
or lower than configMAXSYSCALLINTERRUPTPRIORITY - therefore the numeric
value needs to be equal to or greater than 5 (on the Cortex-M3 the lower the
numeric value the higher the interrupt priority). /

Macros required to setup the timer for the run time stats.
//extern void vConfigureTimerForRunTimeStats( void );
//#define portCONFIGURETIMERFORRUNTIMESTATS() vConfigureTimerForRunTimeStats()


However, at this point I’m a bit lost - I can’t get it to call the task nor blink the light please Obi-Wan you’re my only hope…Should I look at the ISR information? I’ll note that a blue tooth stack is being setup before this stuff is getting called, but this software disables interrupts so I figured it would be ok…

edwards3 wrote on Wednesday, October 26, 2016:

Do you have the FreeRTOS interrupts installed? See answer 1 here http://www.freertos.org/FAQHelp.html If yes do you hit the FreeRTOS SVC handler vPortSVCHandler() in port.c? (put a break point in it to see)

jwschmo wrote on Saturday, October 29, 2016:

Cool - I added the following three lines to FreeRTOSConfig.h:

**#define vPortSVCHandler SVC_Handler
#define xPortPendSVHandler PendSV_Handler
#define xPortSysTickHandler SysTick_Handler

However now I’m getting the following compile error:

build/BOARD/libs/freertos/portable/GCC/ARM_CM3/port.o:port.c:(.text.SysTick_Handler+0x0): first defined here
collect2: error: ld returned 1 exit status
make: *** [build/BOARD/firmware-BOARD.elf] Error 1

Fatal error: local() encountered an error (return code 2)

In the code I’m trying to integrate with there is a timer.cpp that has the following code:

unsigned int SYSTEM_TICK_COUNT;

extern “C” {

void SysTick_Handler() {


If I comment out that code so that the other function can compile correctly (which it will compile if I comment out the above lines) then the processor doesn’t do anything - additionally I moved the “system_Tick_Count” over to the other function call as well :(.


rtel wrote on Sunday, October 30, 2016:

So the code you are integrating with already defines a
SysTick_Handler(). Is the SYSTEM_TICK_COUNT variable it increments used
anywhere? If not, you can just comment out the previous handler. If it
is then you could increment SYSTEM_TICK_COUNT from the FreeRTOS tick hook
. Not if you do that though it will only start incrementing
after the scheduler has been started.