ESP8266 Community Forum

Hi guys,

I'm trying to use the Sigma-Delta in the ESP8266 to get a high frequency PWM output.
I can get an output when I use the i2s_begin(); function but the ESP crashes when I turn it on and off too every two seconds plus I only need the GPIO15 output as the other pins are used for other functions.

I tried using below code from an espressif supplied example but I cannot manage to get any output.
Did anyone already played with this?

http://bbs.espressif.com/viewtopic.php?t=49

[quote]/*
/******************************************************************************
* MODULEName : set_sigma MODULE

EACH PIN CAN CONNET TO A SIGMA-DELTA , ALL PINS SHEARS THE SAME SIGMA-DELTA SOURCE.

THE TARGET DUTY AND FREQUENCY CAN BE MODIFIED VIA THE REG ADDR GPIO_SIGMA_DELTA

THE TARGET FREQUENCY IS DEFINED AS:

FREQ = 80,000,000/prescale * target /256 HZ, 0<target<128
FREQ = 80,000,000/prescale * (256-target) /256 HZ, 128<target<256
target: duty ,0-255
prescale: clk_div,0-255
so the target and prescale will both affect the freq.


YOU CAN DO THE TEST LIKE THIS:
1. INIT : sigma_delta_setup(PERIPHS_IO_MUX_MTDI_U,12,FUNC_GPIO12);
2. USE 312K: set_sigma_duty_312KHz(2);
OR 2. SET VAL: set_sigma_target(uint8 target) AND set_sigma_prescale

3. DEINIT AND DISABLE: sigma_delta_close(uint32 GPIO_NUM), eg.sigma_delta_close(2)

*******************************************************************************/



#include "osapi.h"
#include "c_types.h"
#include "ets_sys.h"
#include "eagle_soc.h"
#include "gpio.h"




#define GPIO_PIN_ADDR(i) (GPIO_PIN0_ADDRESS + i*4)
#define GPIO_SIGMA_DELTA 0x60000368 //defined in gpio register.xls

#define GPIO_SIGMA_DELTA_SETTING_MASK (0x00000001ff)

#define GPIO_SIGMA_DELTA_ENABLE 1
#define GPIO_SIGMA_DELTA_DISABLE (~GPIO_SIGMA_DELTA_ENABLE)
#define GPIO_SIGMA_DELTA_MSB 16
#define GPIO_SIGMA_DELTA_LSB 16
#define GPIO_SIGMA_DELTA_MASK (0x00000001<<GPIO_SIGMA_DELTA_LSB)
#define GPIO_SIGMA_DELTA_GET(x) (((x) & GPIO_SIGMA_DELTA_MASK) >> GPIO_SIGMA_DELTA_LSB)
#define GPIO_SIGMA_DELTA_SET(x) (((x) << GPIO_SIGMA_DELTA_LSB) & GPIO_SIGMA_DELTA_MASK)


#define GPIO_SIGMA_DELTA_TARGET_MSB 7
#define GPIO_SIGMA_DELTA_TARGET_LSB 0
#define GPIO_SIGMA_DELTA_TARGET_MASK (0x000000FF<<GPIO_SIGMA_DELTA_TARGET_LSB)
#define GPIO_SIGMA_DELTA_TARGET_GET(x) (((x) & GPIO_SIGMA_DELTA_TARGET_MASK) >> GPIO_SIGMA_DELTA_TARGET_LSB)
#define GPIO_SIGMA_DELTA_TARGET_SET(x) (((x) << GPIO_SIGMA_DELTA_TARGET_LSB) & GPIO_SIGMA_DELTA_TARGET_MASK)


#define GPIO_SIGMA_DELTA_PRESCALE_MSB 15
#define GPIO_SIGMA_DELTA_PRESCALE_LSB 8
#define GPIO_SIGMA_DELTA_PRESCALE_MASK (0x000000FF<<GPIO_SIGMA_DELTA_PRESCALE_LSB)
#define GPIO_SIGMA_DELTA_PRESCALE_GET(x) (((x) & GPIO_SIGMA_DELTA_PRESCALE_MASK) >> GPIO_SIGMA_DELTA_PRESCALE_LSB)
#define GPIO_SIGMA_DELTA_PRESCALE_SET(x) (((x) << GPIO_SIGMA_DELTA_PRESCALE_LSB) & GPIO_SIGMA_DELTA_PRESCALE_MASK)


/******************************************************************************
* FunctionName : sigma_delta_setup
* Description : Init Pin Config for Sigma_delta , change pin source to sigma-delta
* Parameters : uint32 GPIO_MUX, GPIO MUX REG ,DEFINED IN EAGLE_SOC.H, e.g.: PERIPHS_IO_MUX_MTCK_U
uint32 GPIO_NUM, GPIO NUM ACCORDING TO THE MUX NUM , e.g.: 13 for MTCK
uint32 GPIO_FUNC, GPIO PIN FUNC , DEFINED IN EAGLE_SOC.H , e.g.: FUNC_GPIO13
* Returns : none
*******************************************************************************/
void ICACHE_FLASH_ATTR
sigma_delta_setup(uint32 GPIO_MUX,uint32 GPIO_NUM,uint32 GPIO_FUNC)
{
//============================================================================
//STEP 1: SIGMA-DELTA CONFIG;REG SETUP
GPIO_REG_WRITE(GPIO_SIGMA_DELTA,
(GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))) &(~GPIO_SIGMA_DELTA_SETTING_MASK))|
GPIO_SIGMA_DELTA_SET(GPIO_SIGMA_DELTA_ENABLE)|
GPIO_SIGMA_DELTA_TARGET_SET(0x00)|
GPIO_SIGMA_DELTA_PRESCALE_SET(0x00) );

//============================================================================

//STEP 2: PIN FUNC CONFIG :SET PIN TO GPIO MODE AND ENABLE OUTPUT
PIN_FUNC_SELECT(GPIO_MUX, GPIO_FUNC);
gpio_output_set(0,0,0x1<<GPIO_NUM,0);

//============================================================================

//STEP 3: CONNECT SIGNAL TO GPIO PAD
GPIO_REG_WRITE(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM)),
GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM)))|
GPIO_PIN_SOURCE_SET( SIGMA_AS_PIN_SOURCE ) );
//============================================================================
//ets_printf("test reg gpio mtdi : 0x%08x \n",GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM))));

}




/******************************************************************************
* FunctionName : sigma_delta_close
* Description : DEinit Pin ,from Sigma_delta mode to GPIO input mode
* Parameters : uint32 GPIO_NUM, GPIO NUM ACCORDING TO THE MUX NUM , e.g.: 13 for MTCK
* Returns : none
*******************************************************************************/
void ICACHE_FLASH_ATTR
sigma_delta_close(uint32 GPIO_NUM)
{

//============================================================================
//STEP 1: SIGMA-DELTA DEINIT
GPIO_REG_WRITE(GPIO_SIGMA_DELTA,
(GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))) &(~GPIO_SIGMA_DELTA_SETTING_MASK))|
GPIO_SIGMA_DELTA_SET(GPIO_SIGMA_DELTA_DISABLE)|
GPIO_SIGMA_DELTA_TARGET_SET(0x00)|
GPIO_SIGMA_DELTA_PRESCALE_SET(0x00) );

//ets_printf("test reg gpio sigma : 0x%08x \n",GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))));
//============================================================================

//STEP 2: GPIO OUTPUT DISABLE
gpio_output_set(0,0,0,0x1<<GPIO_NUM);
//============================================================================

//STEP 3: CONNECT GPIO TO PIN PAD
GPIO_REG_WRITE(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM)),
GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_NUM)))|
GPIO_PIN_SOURCE_SET( GPIO_AS_PIN_SOURCE ) );
//============================================================================

}



/******************************************************************************
* FunctionName : set_sigma_target
* Description : SET TARGET DUTY FOR SIGMA-DELTA
* Parameters : uint8 target, DUTY NUM , 1BYTE , DUTY RANGE : 0-255
* Returns : none
*******************************************************************************/
void ICACHE_FLASH_ATTR
set_sigma_target(uint8 target)
{
//set sigma signal duty target
GPIO_REG_WRITE(GPIO_SIGMA_DELTA,
(GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))) &(~GPIO_SIGMA_DELTA_TARGET_MASK))|
GPIO_SIGMA_DELTA_TARGET_SET(target));
}



/******************************************************************************
* FunctionName : set_sigma_prescale
* Description : SET SIGMA-DELTA SIGNAL CLK PRESCALE(CLE_DIV)
* Parameters : uint8 prescale, CLK_DIV , 0-255
* Returns : none
*******************************************************************************/
void ICACHE_FLASH_ATTR
set_sigma_prescale(uint8 prescale)
{
//set sigma signal clk prescale(clk div)
GPIO_REG_WRITE(GPIO_SIGMA_DELTA,
(GPIO_REG_READ(GPIO_PIN_ADDR(GPIO_ID_PIN(GPIO_SIGMA_DELTA_NUM))) &(~GPIO_SIGMA_DELTA_PRESCALE_MASK))|
GPIO_SIGMA_DELTA_PRESCALE_SET(prescale) );

}



/******************************************************************************
* FunctionName : set_sigma_duty_312KHz
* Description : 312K CONFIG EXAMPLE
* Parameters : uint8 duty, TARGET DUTY FOR 312K, 0-255
* Returns : none
*******************************************************************************/
void ICACHE_FLASH_ATTR
set_sigma_duty_312KHz(uint8 duty)
{

uint8 target = 0,prescale=0;
target = (duty>128)?(256-duty):duty;
prescale = (target==0)?0:(target-1);

//freq = 80000 (khz) /256 /duty_target * (prescale+1)
set_sigma_target(duty);//SET DUTY TARGET
set_sigma_prescale(prescale);//SET CLK DIV

}
[/]