Hello,
I would like to implement a RAM check for the STM8 during startup.
According to the manual, SDCC calls "_sdcc_external_startup()" before
jumping to main(). But it seems like - at least for STM8 - this is not
the case. The below bare-metal example should remain in a reset cycle,
because _sdcc_external_startup() triggers a SW reset. I checked that the
SW reset works, so the fact that the LED blinks indicated that
_sdcc_external_startup() is not called. What am I missing?
I build the hexfile with
CFLAGS = -mstm8 --std-sdcc99 --std-c99
LFLAGS = -mstm8 -lstm8 --out-fmt-ihx
For your help thanks a lot in advance and have a great day!
Georg
-------------------------------------------------------------------------------------
#include <stdint.h>
// define peripheral registers (SFR)
#define _SFR_(mem_addr) (*(volatile uint8_t *)(mem_addr))
#define PC_ODR _SFR_(0x500A) // port
C: output state
#define PC_DDR _SFR_(0x500C) // port
C: input(=0) or output(=1)
#define PC_CR1 _SFR_(0x500D) // port
C: input: 0=float, 1=pull-up; output: 0=open-drain, 1=push-pull
#define WWDG_CR _SFR_(0x50D1) // WWDG
watchdog control register
//////////////////
// Called by SDCC prior to jump to main(), see e.g.
http://www.gtoal.com/compilers101/small_c/gbdk/sdcc/doc/sdccman.html/node31.html
//////////////////
uint8_t _sdcc_external_startup()
{
// trigger reset
WWDG_CR = 0x80;
// initialize global variables (=0) / skip global initialization (=1)
return 0;
} // _sdcc_external_startup()
//////////////////
// main program
//////////////////
void main()
{
// debug: check if reset works -> ok
//WWDG_CR = 0x80;
// configure PC5 / LED as output
PC_DDR = (1 << 5);
PC_CR1 = (1 << 5);
// main loop
while (1)
{
// toggle LED
PC_ODR ^= (1 << 5);
// wait some time
for (uint32_t i=0; i<50000L; i++)
__asm__("nop");
} // main loop
} // main()
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