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Add support for hardware Sigma Delta generator

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Provides a simple interface to attach/detach pins to the sigma-delta generator, and get/set the 2 parameters prescaler & target.  Working example that fades the onboard LED is provided.  Code and sample by @stefaandesmet2003.
This commit is contained in:
Earle F. Philhower, III
2018-03-10 12:07:04 -08:00
committed by GitHub
parent 3b269c4a96
commit afcbcd5cc9
4 changed files with 339 additions and 5 deletions
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50
cores/esp8266/sigma_delta.h
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@ -18,15 +18,55 @@
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/*******************************************************************************
* Info Sigma delta module
This module controls the esp8266 internal sigma delta source
Each pin can be connected to the sigma delta source
The target duty and frequency can be modified via the register GPIO_SIGMA_DELTA
THE TARGET FREQUENCY IS DEFINED AS:
FREQ = 80,000,000/prescaler * target /256 HZ, 0<target<128
FREQ = 80,000,000/prescaler * (256-target) /256 HZ, 128<target<256
target: duty cycle,range 0-255
prescaler: is a clock divider, range 0-255
so the target and prescale will both affect the freq.
CPU_FREQ has no influence on the sigma delta frequency.
Usage :
1. sigmaDeltaSetup(0,f) : activate the sigma delta source with frequency f and default duty cycle (0)
2. sigmaDeltaAttachPin(pin), any pin 0..15, TBC if gpio16 supports sigma-delta source
This will set the pin to NORMAL output mode (pinMode(pin,OUTPUT))
3. sigmaDeltaWrite(0,dc) : set the output signal duty cycle, duty cycle = dc/256
*******************************************************************************/
#ifndef SIGMA_DELTA_H
#define SIGMA_DELTA_H
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
void sigma_delta_close(uint32_t gpio);
void set_sigma_target(uint8_t target);
void set_sigma_prescale(uint8_t prescale);
void set_sigma_duty_312KHz(uint8_t duty);
//channel parameter is unused (only for ESP32 compatibility) freq 1220-312500 duty 0-255
void sigmaDeltaEnable(void);
void sigmaDeltaDisable(void);
uint32_t sigmaDeltaSetup(uint8_t channel, uint32_t freq);
void sigmaDeltaWrite(uint8_t channel, uint8_t duty);
uint8_t sigmaDeltaRead(uint8_t channel = 0);
void sigmaDeltaAttachPin(uint8_t pin, uint8_t channel = 0);
void sigmaDeltaDetachPin(uint8_t pin);
bool sigmaDeltaIsPinAttached(uint8_t pin);
// alternative way to control the sigma delta generator frequency
uint8_t sigmaDeltaGetPrescaler(void);
void sigmaDeltaSetPrescaler(uint8_t prescaler);
#ifdef __cplusplus
}
#endif
#endif//SIGMA_DELTA_H