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atmel-samd: Support multiple ADC channels at once.

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Fixes #61
This commit is contained in:
Scott Shawcroft 2017-01-17 14:40:43 -08:00
parent d239dbdc28
commit 179413aec2
2 changed files with 38 additions and 20 deletions
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56
atmel-samd/common-hal/nativeio/AnalogIn.c
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@ -26,6 +26,7 @@
#include <string.h>
#include "py/gc.h"
#include "py/nlr.h"
#include "py/runtime.h"
#include "py/binary.h"
@ -35,6 +36,10 @@
#include "asf/sam0/drivers/adc/adc.h"
#include "samd21_pins.h"
// Number of active ADC channels.
volatile uint8_t active_channel_count;
struct adc_module *adc_instance = NULL;
void common_hal_nativeio_analogin_construct(nativeio_analogin_obj_t* self,
const mcu_pin_obj_t *pin) {
if (!pin->has_adc) {
@ -44,42 +49,55 @@ void common_hal_nativeio_analogin_construct(nativeio_analogin_obj_t* self,
self->pin = pin;
struct adc_config config_adc;
adc_get_config_defaults(&config_adc);
if (adc_instance == NULL) {
struct adc_config config_adc;
adc_get_config_defaults(&config_adc);
config_adc.reference = ADC_REFERENCE_INTVCC1;
config_adc.gain_factor = ADC_GAIN_FACTOR_DIV2;
config_adc.positive_input = self->pin->adc_input;
config_adc.resolution = ADC_RESOLUTION_16BIT;
config_adc.clock_prescaler = ADC_CLOCK_PRESCALER_DIV128;
config_adc.reference = ADC_REFERENCE_INTVCC1;
config_adc.gain_factor = ADC_GAIN_FACTOR_DIV2;
config_adc.positive_input = self->pin->adc_input;
config_adc.resolution = ADC_RESOLUTION_16BIT;
config_adc.clock_prescaler = ADC_CLOCK_PRESCALER_DIV128;
adc_init(&self->adc_instance, ADC, &config_adc);
// Allocate the instance on the heap so we only use the memory when we
// need it.
adc_instance = gc_alloc(sizeof(struct adc_module), false);
adc_init(adc_instance, ADC, &config_adc);
}
self->adc_instance = adc_instance;
active_channel_count++;
}
void common_hal_nativeio_analogin_deinit(nativeio_analogin_obj_t *self) {
// TODO(tannewt): Count how many pins are in use and only reset the ADC when
// none are used.
adc_reset(&self->adc_instance);
active_channel_count--;
if (active_channel_count == 0) {
adc_reset(adc_instance);
gc_free(adc_instance);
// Set our reference to NULL so the GC doesn't mistakenly see the
// pointer in memory.
adc_instance = NULL;
}
reset_pin(self->pin->pin);
}
// TODO(tannewt): Don't turn it all on just for one read. This simplifies
// handling of reading multiple inputs and surviving sleep though so for now its
// ok.
uint16_t common_hal_nativeio_analogin_get_value(nativeio_analogin_obj_t *self) {
adc_enable(&self->adc_instance);
adc_start_conversion(&self->adc_instance);
adc_set_positive_input(adc_instance, self->pin->adc_input);
adc_enable(adc_instance);
adc_start_conversion(adc_instance);
uint16_t data;
enum status_code status = adc_read(&self->adc_instance, &data);
enum status_code status = adc_read(adc_instance, &data);
while (status == STATUS_BUSY) {
status = adc_read(&self->adc_instance, &data);
status = adc_read(adc_instance, &data);
}
if (status == STATUS_ERR_OVERFLOW) {
// TODO(tannewt): Throw an error.
}
adc_disable(&self->adc_instance);
adc_disable(adc_instance);
return data;
}

2
atmel-samd/common-hal/nativeio/types.h
View File

@ -55,7 +55,7 @@
typedef struct {
mp_obj_base_t base;
const mcu_pin_obj_t * pin;
struct adc_module adc_instance;
struct adc_module * adc_instance;
} nativeio_analogin_obj_t;
typedef struct {