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pwm improvements #304

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pwm improvements #304

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2 changes: 2 additions & 0 deletions cores/arduino/Arduino.h
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,8 @@ typedef struct _PinDescription
/* Pins table to be instanciated into variant.cpp */
extern PinDescription g_APinDescription[] ;

extern uint32_t pwmPeriod[4];

#ifdef __cplusplus
} // extern "C"

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30 changes: 15 additions & 15 deletions cores/arduino/wiring_analog.c
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Expand Up @@ -27,11 +27,12 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
/* Standard Arduino PWM resolution */
static int _writeResolution = 8;
static int _readResolution = 10;

uint32_t maxResolutionValue = 0xFF;

void analogWriteResolution(int res)
{
_writeResolution = res;
maxResolutionValue = 0xFFFFFFFF >> (32-res);
}

void analogReadResolution(int res)
Expand All @@ -49,7 +50,7 @@ static inline uint32_t mapResolution(uint32_t value, uint32_t from, uint32_t to)
return value << (to-from);
}

void analogWrite(uint8_t pin, int val)
void analogWrite(uint8_t pin, uint32_t val)
{
if (! digitalPinHasPWM(pin))
{
Expand All @@ -75,20 +76,12 @@ void analogWrite(uint8_t pin, int val)
} else {
/* PWM for everything in between */
PinDescription *p = &g_APinDescription[pin];
uint32_t hcnt = mapResolution(val, _writeResolution, PWM_RESOLUTION);
uint32_t lcnt = PWM_MAX_DUTY_CYCLE - hcnt;
uint32_t offset;

/* For Arduino Uno compatibilty, we scale up frequency on certain pins */
hcnt >>= p->ulPwmScale;
lcnt >>= p->ulPwmScale;

/* Each count must be > 0 */
if (hcnt < PWM_MIN_DUTY_CYCLE)
hcnt = PWM_MIN_DUTY_CYCLE;
if (lcnt < PWM_MIN_DUTY_CYCLE)
lcnt = PWM_MIN_DUTY_CYCLE;

uint32_t offset;

uint32_t hcnt = (val/(float)maxResolutionValue) * pwmPeriod[p->ulPwmChan];
uint32_t lcnt = pwmPeriod[p->ulPwmChan] - hcnt;

/* Set the high count period (duty cycle) */
offset = ((p->ulPwmChan * QRK_PWM_N_LCNT2_LEN) + QRK_PWM_N_LOAD_COUNT2);
MMIO_REG_VAL(QRK_PWM_BASE_ADDR + offset) = hcnt;
Expand Down Expand Up @@ -145,6 +138,13 @@ uint32_t analogRead(uint32_t pin)

}

void analogWriteFrequency(uint8_t pin, uint32_t freq)
{
//convert frequency to period in clock ticks
PinDescription *p = &g_APinDescription[pin];
pwmPeriod[p->ulPwmChan] = F_CPU / freq;
}

#ifdef __cplusplus
}
#endif
11 changes: 10 additions & 1 deletion cores/arduino/wiring_analog.h
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Expand Up @@ -33,6 +33,8 @@ typedef enum _eAnalogReference
AR_DEFAULT,
} eAnalogReference ;

#define PWM_PERIOD 65306 //490 Hz

/*
* \brief Configures the reference voltage used for analog input (i.e. the value used as the top of the input range).
* This function is kept only for compatibility with existing AVR based API.
Expand All @@ -47,7 +49,7 @@ extern void analogReference( eAnalogReference ulMode ) ;
* \param pin
* \param val
*/
extern void analogWrite( uint8_t pin, int val ) ;
extern void analogWrite( uint8_t pin, uint32_t val ) ;
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Is this required (changing the API)? Assuming we're still just looking for a positive integer, can you leave the analogWrite declaration as it was, and instead cast to uint32_t as needed?


/*
* \brief Reads the value from the specified analog pin.
Expand All @@ -72,6 +74,13 @@ extern void analogReadResolution(int res);
*/
extern void analogWriteResolution(int res);

/*
* \brief Set the frequency of analogWrite parameters.
*
* \param res
*/
extern void analogWriteFrequency(uint8_t pin, uint32_t freq);
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@eriknyquist eriknyquist Sep 29, 2016 •
edited
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would recommend using int for both pin and freq, if possible-- just more Arduino-y :)


#ifdef __cplusplus
}
#endif
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1 change: 1 addition & 0 deletions variants/arduino_101/variant.cpp
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Expand Up @@ -98,6 +98,7 @@ PinDescription g_APinDescription[]=
{ 3, SOC_GPIO_32, SOC_GPIO, SOC_GPIO_AON_BASE_ADDR, 3, GPIO_MUX_MODE, INVALID, INVALID, INVALID, INPUT_MODE }, // Arduino IO28
} ;

uint32_t pwmPeriod[] = {PWM_PERIOD, PWM_PERIOD/2, PWM_PERIOD/2, PWM_PERIOD};
#ifdef __cplusplus
}
#endif
Expand Down