Translating make file for freeRTOS, libopencm3 to platformio.ini

maxgerhardt · December 27, 2019, 6:11pm

Well looking at this opencm3.c file:

bjwschaap/platformio-libopencm3-freertos/blob/1988e18b2350c6e88d65341c82d22348766082a7/lib/rtos/opencm3.c#L12-L27


      
          extern void vPortSVCHandler( void ) __attribute__ (( naked ));
          extern void xPortPendSVHandler( void ) __attribute__ (( naked ));
          extern void xPortSysTickHandler( void );
          
          
void sv_call_handler(void) {
          	vPortSVCHandler();
          }
          
          
void pend_sv_handler(void) {
          	xPortPendSVHandler();
          }
          
          
void sys_tick_handler(void) {
          	xPortSysTickHandler();
          }

These are supposed to be the ISR handlers. Looking at vector.c file

github.com

libopencm3/libopencm3/blob/master/lib/cm3/vector.c

/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2010 Piotr Esden-Tempski <piotr@esden.net>,
 * Copyright (C) 2012 chrysn <chrysn@fsfe.org>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library 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.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library. If not, see <http://www.gnu.org/licenses/>.
 */

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At the end of the file, WEAK symbols are defined. It may be the case that when the linking is done for libopencm3, the opencm3.c file is not yet known so it links it with the empty handlers.

A way around that may be to not link the frameworks seperately, but all at once. This can be achieved using lib_archive = no in the platformio.ini (docs).

This increases the size of the code in the flash from

RAM:   [========= ]  86.2% (used 17664 bytes from 20480 bytes)
Flash: [=         ]   5.2% (used 3424 bytes from 65536 bytes)

to

RAM:   [========= ]  86.2% (used 17664 bytes from 20480 bytes)
Flash: [=         ]   5.5% (used 3596 bytes from 65536 bytes)

Does that help?

Also, it shold be easily debuggable using a STLinkv2 to check if the handlers in opencm3.c are called at all, which would give further insight into the problem. PIO’s debugger is free to use in VSCode.