../watch_faces/thermistor/thermistor_readout_face.c \
../watch_faces/thermistor/thermistor_logging_face.c \
../watch_faces/demos/character_set_face.c \
+ ../watch_faces/demos/voltage_face.c \
../watch_faces/complications/beats_face.c \
# Leave this line at the bottom of the file; it has all the targets for making your project.
#include "thermistor_logging_face.h"
#include "character_set_face.h"
#include "beats_face.h"
+#include "voltage_face.h"
const watch_face_t watch_faces[] = {
simple_clock_face,
--- /dev/null
+#include <stdlib.h>
+#include <string.h>
+#include "voltage_face.h"
+#include "watch.h"
+
+void _voltage_face_update_display() {
+ char buf[14];
+ float voltage = (float)watch_get_vcc_voltage() / 1000.0;
+ sprintf(buf, "BA %4.2f V", voltage);
+ // printf("%s\n", buf);
+ watch_display_string(buf, 0);
+}
+
+void voltage_face_setup(movement_settings_t *settings, void ** context_ptr) {
+ (void) settings;
+ (void) context_ptr;
+}
+
+void voltage_face_activate(movement_settings_t *settings, void *context) {
+ (void) settings;
+ (void) context;
+ watch_enable_adc();
+ // if we set the reference voltage here, watch_get_vcc_voltage won't do it over and over
+ watch_set_analog_reference_voltage(ADC_REFERENCE_INTREF);
+}
+
+bool voltage_face_loop(movement_event_t event, movement_settings_t *settings, void *context) {
+ (void) settings;
+ (void) context;
+ watch_date_time date_time;
+ switch (event.event_type) {
+ case EVENT_MODE_BUTTON_UP:
+ movement_move_to_next_face();
+ break;
+ case EVENT_LIGHT_BUTTON_DOWN:
+ movement_illuminate_led();
+ break;
+ case EVENT_ACTIVATE:
+ _voltage_face_update_display();
+ break;
+ case EVENT_TICK:
+ date_time = watch_rtc_get_date_time();
+ if (date_time.unit.second % 5 == 4) {
+ watch_set_indicator(WATCH_INDICATOR_SIGNAL);
+ } else if (date_time.unit.second % 5 == 0) {
+ _voltage_face_update_display();
+ watch_clear_indicator(WATCH_INDICATOR_SIGNAL);
+ }
+ break;
+ case EVENT_TIMEOUT:
+ movement_move_to_face(0);
+ break;
+ default:
+ break;
+ }
+
+ return true;
+}
+
+void voltage_face_resign(movement_settings_t *settings, void *context) {
+ (void) settings;
+ (void) context;
+ // make sure to restore the default in the end.
+ watch_set_analog_reference_voltage(ADC_REFCTRL_REFSEL_INTVCC2_Val);
+ watch_disable_adc();
+}
--- /dev/null
+#ifndef VOLTAGE_FACE_H_
+#define VOLTAGE_FACE_H_
+
+#include "movement.h"
+
+void voltage_face_setup(movement_settings_t *settings, void ** context_ptr);
+void voltage_face_activate(movement_settings_t *settings, void *context);
+bool voltage_face_loop(movement_event_t event, movement_settings_t *settings, void *context);
+void voltage_face_resign(movement_settings_t *settings, void *context);
+
+static const watch_face_t voltage_face = {
+ voltage_face_setup,
+ voltage_face_activate,
+ voltage_face_loop,
+ voltage_face_resign,
+ NULL
+};
+
+#endif // VOLTAGE_FACE_H_
\ No newline at end of file
_watch_sync_adc();
}
+void watch_set_analog_reference_voltage(watch_adc_reference_voltage reference) {
+ ADC->CTRLA.bit.ENABLE = 0;
+
+ if (reference == ADC_REFERENCE_INTREF) SUPC->VREF.bit.VREFOE = 1;
+ else SUPC->VREF.bit.VREFOE = 0;
+
+ ADC->REFCTRL.bit.REFSEL = reference;
+ ADC->CTRLA.bit.ENABLE = 1;
+ _watch_sync_adc();
+ // throw away one measurement after reference change (the channel doesn't matter).
+ _watch_get_analog_value(ADC_INPUTCTRL_MUXPOS_SCALEDCOREVCC);
+}
+
+uint16_t watch_get_vcc_voltage() {
+ // stash the previous reference so we can restore it when we're done.
+ uint8_t oldref = ADC->REFCTRL.bit.REFSEL;
+
+ // if we weren't already using the internal reference voltage, select it now.
+ if (oldref != ADC_REFERENCE_INTREF) watch_set_analog_reference_voltage(ADC_REFERENCE_INTREF);
+
+ // get the data
+ uint32_t raw_val = _watch_get_analog_value(ADC_INPUTCTRL_MUXPOS_SCALEDIOVCC_Val);
+
+ // restore the old reference, if needed.
+ if (oldref != ADC_REFERENCE_INTREF) watch_set_analog_reference_voltage(oldref);
+
+ return (uint16_t)((raw_val * 1000) / (1024 * 1 << ADC->AVGCTRL.bit.SAMPLENUM));
+}
+
inline void watch_disable_analog_input(const uint8_t pin) {
gpio_set_pin_function(pin, GPIO_PIN_FUNCTION_OFF);
}
**/
void watch_set_analog_sampling_length(uint8_t cycles);
+typedef enum {
+ ADC_REFERENCE_INTREF = ADC_REFCTRL_REFSEL_INTREF_Val,
+ ADC_REFERENCE_VCC_DIV1POINT6 = ADC_REFCTRL_REFSEL_INTVCC0_Val,
+ ADC_REFERENCE_VCC_DIV2 = ADC_REFCTRL_REFSEL_INTVCC1_Val,
+ ADC_REFERENCE_VCC = ADC_REFCTRL_REFSEL_INTVCC2_Val,
+} watch_adc_reference_voltage;
+
+
+/** @brief Selects the reference voltage to use for analog readings. Default is ADC_REFERENCE_VCC.
+ * @param reference One of ADC_REFERENCE_VCC, ADC_REFERENCE_VCC_DIV1POINT6, ADC_REFERENCE_VCC_DIV2
+ * or ADC_REFERENCE_INTREF.
+ * @details In order to turn an analog voltage into a 16-bit integer, the ADC needs to compare the
+ * measured voltage to a reference point. For example, if you were powering the watch with
+ * VCC == 3.0V and you had two 10K resistors connected in series from 3V to GND, you could
+ * expect to get 3 volts when you measure the top of the voltage divider, 0 volts at the
+ * bottom, and 1.5 volts in the middle. If you read these values uising a reference voltage
+ * of ADC_REFERENCE_VCC, the top value would be about 65535, the bottom about 0, and the
+ * middle about 32768. However! If we used ADC_REFERENCE_VCC_DIV2 as our reference, we would
+ * expect to get 65535 both at the top and the middle, because the largest value the ADC can
+ * measure in this configutation is 1.5V (VCC / 2).
+ *
+ * By changing the reference voltage from ADC_REFERENCE_VCC to ADC_REFERENCE_VCC_DIV1POINT6
+ * or ADC_REFERENCE_VCC_DIV2, you can get more resolution when measuring small voltages (i.e.
+ * a phototransistor circuit in low light).
+ *
+ * There is also a special reference voltage called ADC_REFERENCE_INTREF. The SAM L22's
+ * Supply Controller provides a selectable voltage reference (by default, 1.024 V) that you
+ * can select as a reference voltage for ADC conversions. Unlike the three references we
+ * talked about in the last paragraph, this reference voltage does not depend on VCC, which
+ * makes it very useful for measuring the battery voltage (since you can't really compare
+ * VCC to itself). You can change the INTREF voltage to 2.048 or 4.096 V by poking at the
+ * supply controller's VREF register, but the watch library does not support this use case.
+ **/
+void watch_set_analog_reference_voltage(watch_adc_reference_voltage reference);
+
+/** @brief Returns the voltage of the VCC supply in millivolts (i.e. 3000 mV == 3.0 V). If running on
+ * a coin cell, this will be the battery voltage.
+ * @details Unlike other ADC functions, this function does not return a raw value from the ADC, but
+ * rather scales it to an actual number of millivolts. This is because the ADC doesn't let
+ * us measure VCC per se; it instead lets us measure VCC / 4, and we choose to measure it
+ * against the internal reference voltage of 1.024 V. In short, the ADC gives us a number
+ * that's complicated to deal with, so we just turn it into a useful number for you :)
+ * @note This function depends on INTREF being 1.024V. If you have changed it by poking at the supply
+ * controller's VREF.SEL bits, this function will return inaccurate values.
+ */
+uint16_t watch_get_vcc_voltage();
+
/** @brief Disables the analog circuitry on the selected pin.
* @param pin One of pins A0-A4.
*/
projects / sensor-watch.git / commitdiff