Jeff Epler
953694d56c
This mostly means changing `void foo()` to `void foo(void)` at the function definition site. This was previously only an error if the declaration site didn't have `(void)`, but the unix coverage build enables the more strict warning and there's little difficulty in resolving these diagnostics. .. other ports can be done too, if desired.
108 lines
3.8 KiB
C
108 lines
3.8 KiB
C
// This file is part of the CircuitPython project: https://circuitpython.org
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//
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// SPDX-FileCopyrightText: Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
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// SPDX-FileCopyrightText: Copyright (c) 2018 Nick Moore for Adafruit Industries
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//
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// SPDX-License-Identifier: MIT
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#include <string.h>
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#include <stdio.h>
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#include "py/runtime.h"
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#include "py/mphal.h"
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#include "shared-bindings/touchio/TouchIn.h"
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#include "shared-bindings/microcontroller/Pin.h"
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#include "shared-bindings/digitalio/Pull.h"
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// This is a capacitive touch sensing routine using a single digital pin.
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// For pull==PULL_DOWN, the pin should be connected to the sensing pad and to ground
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// via a 1Mohm or thereabout drain resistor. When a reading is taken,
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// the pin's capacitance is charged by setting it to a digital output
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// 'high' for a few microseconds, and then it is changed to a high
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// impedance input. We measure how long it takes to discharge through
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// the resistor (around 50us), using a busy-waiting loop, and average
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// over N_SAMPLES cycles to reduce the effects of noise.
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// For the pull=PULL_UP case, the 1M resistor is connected to 3v3, the pin is
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// driven 'low' then measure how long it takes to go 'high'.
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#define N_SAMPLES 10
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#define TIMEOUT_TICKS 10000
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static uint16_t get_raw_reading(touchio_touchin_obj_t *self) {
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uint16_t ticks = 0;
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// state to charge pin to: if pull-down or None, pull HIGH, if pull-up, pull LOW
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bool pincharge = !(self->pull == PULL_UP);
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for (uint16_t i = 0; i < N_SAMPLES; i++) {
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// set pad to digital output 'pincharge' for 10us to charge it
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common_hal_digitalio_digitalinout_switch_to_output(self->digitalinout, pincharge, DRIVE_MODE_PUSH_PULL);
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mp_hal_delay_us(10);
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// set pad back to an input and take some samples
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common_hal_digitalio_digitalinout_switch_to_input(self->digitalinout, PULL_NONE);
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while (common_hal_digitalio_digitalinout_get_value(self->digitalinout) == pincharge) {
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if (ticks >= TIMEOUT_TICKS) {
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return TIMEOUT_TICKS;
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}
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ticks++;
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}
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}
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return ticks;
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}
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void common_hal_touchio_touchin_construct(touchio_touchin_obj_t *self, const mcu_pin_obj_t *pin, const digitalio_pull_t pull) {
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common_hal_mcu_pin_claim(pin);
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self->digitalinout = mp_obj_malloc(digitalio_digitalinout_obj_t, &digitalio_digitalinout_type);
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common_hal_digitalio_digitalinout_construct(self->digitalinout, pin);
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self->pull = pull;
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uint16_t raw_reading = get_raw_reading(self);
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if (raw_reading == TIMEOUT_TICKS) {
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common_hal_touchio_touchin_deinit(self);
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if (self->pull == PULL_UP) {
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mp_raise_ValueError(MP_ERROR_TEXT("No pullup on pin; 1Mohm recommended"));
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} else {
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mp_raise_ValueError(MP_ERROR_TEXT("No pulldown on pin; 1Mohm recommended"));
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}
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}
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self->threshold = raw_reading * 1.05 + 100;
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}
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bool common_hal_touchio_touchin_deinited(touchio_touchin_obj_t *self) {
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return self->digitalinout == MP_OBJ_NULL;
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}
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void common_hal_touchio_touchin_deinit(touchio_touchin_obj_t *self) {
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if (common_hal_touchio_touchin_deinited(self)) {
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return;
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}
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common_hal_digitalio_digitalinout_deinit(self->digitalinout);
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self->digitalinout = MP_OBJ_NULL;
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}
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void touchin_reset(void) {
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}
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bool common_hal_touchio_touchin_get_value(touchio_touchin_obj_t *self) {
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uint16_t reading = get_raw_reading(self);
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return reading > self->threshold;
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}
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uint16_t common_hal_touchio_touchin_get_raw_value(touchio_touchin_obj_t *self) {
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return get_raw_reading(self);
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}
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uint16_t common_hal_touchio_touchin_get_threshold(touchio_touchin_obj_t *self) {
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return self->threshold;
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}
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void common_hal_touchio_touchin_set_threshold(touchio_touchin_obj_t *self,
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uint16_t new_threshold) {
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self->threshold = new_threshold;
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}
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