You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
circuitpython/ports/atmel-samd/common-hal/analogio/AnalogIn.c

131 lines
4.5 KiB

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "common-hal/analogio/AnalogIn.h"
#include <string.h>
#include "py/gc.h"
#include "py/nlr.h"
#include "py/runtime.h"
#include "py/binary.h"
#include "py/mphal.h"
#include "samd/adc.h"
#include "shared-bindings/analogio/AnalogIn.h"
#include "supervisor/shared/translate.h"
#include "atmel_start_pins.h"
#include "hal/include/hal_adc_sync.h"
#include "hpl/gclk/hpl_gclk_base.h"
#ifdef SAMD21
#include "hpl/pm/hpl_pm_base.h"
#endif
void common_hal_analogio_analogin_construct(analogio_analogin_obj_t* self,
const mcu_pin_obj_t *pin) {
uint8_t adc_index;
uint8_t adc_channel = 0xff;
for (adc_index = 0; adc_index < NUM_ADC_PER_PIN; adc_index++) {
// TODO(tannewt): Only use ADC0 on the SAMD51 when touch isn't being
// used.
if (pin->adc_input[adc_index] != 0xff) {
adc_channel = pin->adc_input[adc_index];
break;
}
}
if (adc_channel == 0xff) {
// No ADC function on that pin
mp_raise_ValueError(translate("Pin does not have ADC capabilities"));
}
claim_pin(pin);
gpio_set_pin_function(pin->number, GPIO_PIN_FUNCTION_B);
static Adc* adc_insts[] = ADC_INSTS;
self->instance = adc_insts[adc_index];
self->channel = adc_channel;
self->pin = pin;
}
bool common_hal_analogio_analogin_deinited(analogio_analogin_obj_t *self) {
return self->pin == NULL;
}
void common_hal_analogio_analogin_deinit(analogio_analogin_obj_t *self) {
if (common_hal_analogio_analogin_deinited(self)) {
return;
}
reset_pin_number(self->pin->number);
self->pin = NULL;
}
void analogin_reset() {
}
uint16_t common_hal_analogio_analogin_get_value(analogio_analogin_obj_t *self) {
// Something else might have used the ADC in a different way,
// so we completely re-initialize it.
struct adc_sync_descriptor adc;
samd_peripherals_adc_setup(&adc, self->instance);
// Full scale is 3.3V (VDDANA) = 65535.
// On SAMD21, INTVCC1 is 0.5*VDDANA. On SAMD51, INTVCC1 is 1*VDDANA.
// So on SAMD21 only, divide the input by 2, so full scale will match 0.5*VDDANA.
adc_sync_set_reference(&adc, ADC_REFCTRL_REFSEL_INTVCC1_Val);
#ifdef SAMD21
adc_sync_set_channel_gain(&adc, self->channel, ADC_INPUTCTRL_GAIN_DIV2_Val);
#endif
adc_sync_set_resolution(&adc, ADC_CTRLB_RESSEL_12BIT_Val);
adc_sync_enable_channel(&adc, self->channel);
// We need to set the inputs because the above channel enable only enables the ADC.
adc_sync_set_inputs(&adc, self->channel, ADC_INPUTCTRL_MUXNEG_GND_Val, self->channel);
// Read twice and discard first result, as recommended in section 14 of
// http://www.atmel.com/images/Atmel-42645-ADC-Configurations-with-Examples_ApplicationNote_AT11481.pdf
// "Discard the first conversion result whenever there is a change in ADC configuration
// like voltage reference / ADC channel change"
// Empirical observation shows the first reading is quite different than subsequent ones.
uint16_t value;
adc_sync_read_channel(&adc, self->channel, ((uint8_t*) &value), 2);
adc_sync_read_channel(&adc, self->channel, ((uint8_t*) &value), 2);
adc_sync_deinit(&adc);
// Shift the value to be 16 bit.
return value << 4;
}
float common_hal_analogio_analogin_get_reference_voltage(analogio_analogin_obj_t *self) {
return 3.3f;
}