ESP8266 Community Forum

- Fri Dec 02, 2016 3:38 pm #59024 Hello,

i just wanted to try to bitbang some bits via GPIO 0 and GPIO 2 but my module resets after every second or so even though i have some delays in my code (i read those are needed to prevent resets). I use the latest esp-open-sdk on Debian 8.6 64-bit. This is the message i get after the reset @115200 Baud

Code: Select all ets Jan  8 2013,rst cause:2, boot mode:(3,7)

load 0x40100000, len 27564, room 16
tail 12
chksum 0x1d
ho 0 tail 12 room 4
load 0x3ffe8000, len 892, room 12
tail 0
chksum 0xc5
load 0x3ffe8380, len 288, room 8
tail 8
chksum 0x09
csum 0x09


and this is my source code:

Code: Select all#include "ets_sys.h"
#include "osapi.h"
#include "gpio.h"
#include "os_type.h"

#define SCK BIT2
#define SDA BIT0

static volatile os_timer_t timer;

void setHigh(uint32_t GPIO){
  gpio_output_set(0,0,0,GPIO);
}

void setLow(uint32_t GPIO){
  gpio_output_set(0,GPIO,GPIO,0);
}

void setGPIOs(){
  gpio_init();
  PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO2_U, FUNC_GPIO2);
   PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO0_U, FUNC_GPIO0);
}

void transferByte(uint8_t byte){
  uint8_t bitCycle;
  for(bitCycle = 7; bitCycle >= 0; bitCycle++){
    uint8_t currentBit = (byte >> bitCycle) & 1;
    if(currentBit == 1)
      setHigh(SDA);
    else
      setLow(SDA);
    setHigh(SCK);
    os_delay_us(3);
    setLow(SCK);
  }
  os_delay_us(10);
}

void ICACHE_FLASH_ATTR user_init()
{
  uint8_t byte = 0b10101010;
  setGPIOs();
  os_timer_setfn(&timer,(os_timer_func_t*)transferByte,byte);
  os_timer_arm(&timer,10,1);
}



Any help would be very much appreciated!

- Sat Dec 03, 2016 8:52 am #59041 From SDK, you are using gpio_output_set() improperly with argument at the wrong location.

Your setHigh() function should look more like :

Code: Select allvoid setHigh(uint32_t GPIO){
  gpio_output_set(GPIO,0,GPIO, 0);
}


EDIT : Oh ! I see now ... your previous setHigh() function is disabling output to leave only the pullUp.
So, problem must be elsewhere.

EDIT2 : Oh !!! I've found it : your for loop has bitCycle++ instead of bitCycle-- .

- Sat Dec 03, 2016 9:25 am #59043 Thanks a lot for your reply. Another problem is that a uint8_t value is always positive, i changed to a in16_t value.