Hi,
Some expert knowledge needed here. We are trying to extend small functionality in an old MBED LPC1768 (devboard) based Firmware of which the code was written on top of Mbed OS5 (v5.15.8).
We are trying to write a file to the onboard flash chip from a second thread. We noticed that our save() method works fine as long as we don’t initialise our display. Which is a ST7789 SPI based display:
lcd = new Adafruit_ST7789(p5, p6, p7, p21, p22, p24);
I noticed that in the init() method of the Adafruit_ST7789 there are wait_ms() commands. Whenever I comment those lines, then my display doesn’t work but the LocalFileSystem access works and the code doesn’t crash. What is the relation between these 2 functionalities? Does the MBED LPC1768’ onboard flash somehow use resources of that SPI bus?
Pseudo demo code:
#include "mbed.h"
Adafruit_ST7789 *lcd;
Thread eventThread;
EventQueue queue;
int main(){
/* works */
save();
/* Initialize the SPI display */
lcd = new Adafruit_ST7789(p5, p6, p7, p21, p22, p24);
lcd->init();
/* Doesn't work and result in a crash / hardfault as soon as it hits fopen() in the method */
this->save();
while(1){}
}
void save(){
printf("Saving to flash..");
LocalFileSystem local("local");
FILE *fp = fopen("/local/test.txt", "w");
fprintf(fp, "Hello World!");
fclose(fp);
}
I think it has to do with this issue:
The mbed interface semihosting is disconnected as part of going to sleep, and can not be restored.
- Flash re-programming and the USB serial port will remain active, but the mbed program will no longer be
- able to access the LocalFileSystem
How can we prevent it from going to sleep?
Kind regards,
Bastiaan