ESP8266 Community Forum

- Mon Nov 03, 2014 1:55 pm #2196

I dont Inderstand how to write in registers. For example in PIN_OUT
WRITE_PERI_REG(PIN_OUT,0x05) set gpio0 and gpio2 high. Right or no?

No. The purpose of defining tzhe registers directly is to allow direct access to them, instead of going through the WRITE_PERI_REG stuff. For example:

PIN_OUT = 0x00000005;

should do what you want. Of course the pin has to be set up as an output first.

Greetings,

Chris

Don't understand how we can one number assign another number...

- Mon Nov 03, 2014 3:32 pm #2202 From my understanding (since I didn't verify the PROVIDE macro), it is defining a register pointer, so having PROVIDE(PIN_OUT = 0x60000300); and then PIN_OUT = 0x05 is equivalent of doing *(0x60000300) = 0x05.
Again, as mentionned earlier, this will change the states of several GPIOs at the same time, so it is better to control individual GPIO using PIN_OUT_SET/PIN_OUT_CLEAR macros.

- Mon Nov 03, 2014 3:45 pm #2203 I can understand the confusion a bit and I must admit I had to understand the "thinking as well". So if I understand. Setting pin 0 as output and toggeling it could be done as:

initalizing:

Code: Select all
#define GPIO    0     
PIN_DIR_OUTPUT = GPIO;


some loop:

Code: Select allvoid loop() {
   //
   // sets GPIO pin 0 HIGH
   //
   PIN_OUT_SET = GPIO;
   some_delay();
   //
   // clears GPIO pin 0
   //
   PIN_OUT_CLEAR = GPIO;
   some_delay();
}


And if I would like to change this to GPIO2 I just need to change the define in the setup

- Tue Dec 30, 2014 8:06 am #5961

this is actually described in "6-ESP8266 FAQ文档_v0.2.pdf" (under GPIO, shift register).

I tested it once, however with org. defines (here for GPIO4):

WRITE_PERI_REG(PERIPHS_GPIO_BASEADDR+GPIO_OUT_W1TS_ADDRESS,BIT4);
WRITE_PERI_REG(PERIPHS_GPIO_BASEADDR+GPIO_OUT_W1TC_ADDRESS,BIT4);

one can of course use predefined macro (and that is described in the pdf above):

GPIO_REG_WRITE(GPIO_OUT_W1TS_ADDRESS,BIT4);
GPIO_REG_WRITE(GPIO_OUT_W1TC_ADDRESS,BIT4)

(a quick look into eagle_soc.h, #define GPIO_REG_WRITE(reg, val) WRITE_PERI_REG(PERIPHS_GPIO_BASEADDR + reg, val))

Anyway, the result is of course exact the same.

When writing directly to the out register one can toggle a PIN with ~5714kHz instead of ~825kHz, which was the
case when using GPIO_OUTPUT_SET(GPIO_ID_PIN(4), 1) instead.

One need to know that only GPIO0 to GPIO15 can be accessed like that, to use GPIO16 one need to use the slow API.

I try this macro for driving multiple shift register but nothing. Is there some one how can explain how to direct write out pin ? Here a simple sample code :

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

// see eagle_soc.h for these definitions
#define DELAY 2000 /* milliseconds */
LOCAL os_timer_t blink_timer;
LOCAL uint8_t led_state=0;

LOCAL ICACHE_FLASH_ATTR blink_cb(void *arg){   
  if (led_state == 0){
    GPIO_REG_WRITE(GPIO_OUT_ADDRESS,(GPIO_REG_READ(GPIO_OUT_ADDRESS) & (uint32)(0xFFFFFFFB)) | (uint32)(0x4));
//    gpio_output_set(0,BIT2|BIT12, BIT2|BIT12,0);
    led_state = 1;
  }
  else{
    GPIO_REG_WRITE(GPIO_OUT_ADDRESS,(GPIO_REG_READ(GPIO_OUT_ADDRESS) & (uint32)(0xFFFFFFFB)));
//    gpio_output_set(BIT2|BIT12, 0, BIT2|BIT12,0);
    led_state = 0;
  }
}

void user_init(void){
  PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO2_U,FUNC_GPIO2);
//  PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO4_U,FUNC_GPIO4);
//  PIN_FUNC_SELECT(PERIPHS_IO_MUX_MTDI_U,FUNC_GPIO12);

// "don't forget to set up the pin first" as output in this case
  gpio_output_set(0, 0, BIT2,0);


  os_timer_disarm(&blink_timer);
  os_timer_setfn(&blink_timer, (os_timer_func_t *)blink_cb, (void *)0);
  os_timer_arm(&blink_timer, DELAY, 1);
}


EDIT :
I don't delete this post for the code sample but I give the solution : " Don't forget to set up the pin first." grrrrr
besause "gpio_output_set" defined the type output or input but here you MUST do this in PIN set up. (I update the code sample)