218 lines
5.9 KiB
C
218 lines
5.9 KiB
C
/*
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* Copyright (c) 2020 The ZMK Contributors
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*
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* SPDX-License-Identifier: MIT
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*/
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#define DT_DRV_COMPAT zmk_battery_voltage_divider
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#include <device.h>
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#include <drivers/gpio.h>
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#include <drivers/adc.h>
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#include <drivers/sensor.h>
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#include <logging/log.h>
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LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
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struct io_channel_config {
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const char *label;
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uint8_t channel;
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};
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struct gpio_channel_config {
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const char *label;
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uint8_t pin;
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uint8_t flags;
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};
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struct bvd_config {
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struct io_channel_config io_channel;
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struct gpio_channel_config power_gpios;
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uint32_t output_ohm;
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uint32_t full_ohm;
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};
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struct bvd_data {
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struct device *adc;
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struct device *gpio;
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struct adc_channel_cfg acc;
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struct adc_sequence as;
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uint16_t adc_raw;
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uint16_t voltage;
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uint8_t state_of_charge;
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};
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static uint8_t lithium_ion_mv_to_pct(int16_t bat_mv) {
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// Simple linear approximation of a battery based off adafruit's discharge graph:
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// https://learn.adafruit.com/li-ion-and-lipoly-batteries/voltages
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if (bat_mv >= 4200) {
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return 100;
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} else if (bat_mv <= 3450) {
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return 0;
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}
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return bat_mv * 2 / 15 - 459;
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}
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static int bvd_sample_fetch(struct device *dev, enum sensor_channel chan) {
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struct bvd_data *drv_data = dev->driver_data;
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const struct bvd_config *drv_cfg = dev->config_info;
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struct adc_sequence *as = &drv_data->as;
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// Make sure selected channel is supported
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if (chan != SENSOR_CHAN_GAUGE_VOLTAGE && chan != SENSOR_CHAN_GAUGE_STATE_OF_CHARGE &&
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chan != SENSOR_CHAN_ALL) {
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LOG_DBG("Selected channel is not supported: %d.", chan);
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return -ENOTSUP;
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}
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int rc = 0;
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// Enable power GPIO if present
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if (drv_data->gpio) {
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rc = gpio_pin_set(drv_data->gpio, drv_cfg->power_gpios.pin, 1);
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if (rc != 0) {
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LOG_DBG("Failed to enable ADC power GPIO: %d", rc);
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return rc;
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}
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}
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// Read ADC
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rc = adc_read(drv_data->adc, as);
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as->calibrate = false;
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if (rc == 0) {
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int32_t val = drv_data->adc_raw;
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adc_raw_to_millivolts(adc_ref_internal(drv_data->adc), drv_data->acc.gain, as->resolution,
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&val);
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uint16_t millivolts = val * (uint64_t)drv_cfg->full_ohm / drv_cfg->output_ohm;
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LOG_DBG("ADC raw %d ~ %d mV => %d mV\n", drv_data->adc_raw, val, millivolts);
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uint8_t percent = lithium_ion_mv_to_pct(millivolts);
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LOG_DBG("Percent: %d", percent);
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drv_data->voltage = millivolts;
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drv_data->state_of_charge = percent;
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} else {
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LOG_DBG("Failed to read ADC: %d", rc);
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}
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// Disable power GPIO if present
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if (drv_data->gpio) {
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int rc2 = gpio_pin_set(drv_data->gpio, drv_cfg->power_gpios.pin, 0);
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if (rc2 != 0) {
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LOG_DBG("Failed to disable ADC power GPIO: %d", rc2);
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return rc2;
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}
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}
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return rc;
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}
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static int bvd_channel_get(struct device *dev, enum sensor_channel chan, struct sensor_value *val) {
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struct bvd_data *drv_data = dev->driver_data;
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switch (chan) {
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case SENSOR_CHAN_GAUGE_VOLTAGE:
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val->val1 = drv_data->voltage / 1000;
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val->val2 = (drv_data->voltage % 1000) * 1000U;
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break;
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case SENSOR_CHAN_GAUGE_STATE_OF_CHARGE:
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val->val1 = drv_data->state_of_charge;
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val->val2 = 0;
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break;
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default:
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return -ENOTSUP;
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}
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return 0;
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}
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static const struct sensor_driver_api bvd_api = {
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.sample_fetch = bvd_sample_fetch,
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.channel_get = bvd_channel_get,
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};
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static int bvd_init(struct device *dev) {
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struct bvd_data *drv_data = dev->driver_data;
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const struct bvd_config *drv_cfg = dev->config_info;
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drv_data->adc = device_get_binding(drv_cfg->io_channel.label);
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if (drv_data->adc == NULL) {
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LOG_ERR("ADC %s failed to retrieve", drv_cfg->io_channel.label);
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return -ENODEV;
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}
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int rc = 0;
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if (drv_cfg->power_gpios.label) {
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drv_data->gpio = device_get_binding(drv_cfg->power_gpios.label);
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if (drv_data->gpio == NULL) {
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LOG_ERR("Failed to get GPIO %s", drv_cfg->power_gpios.label);
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return -ENODEV;
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}
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rc = gpio_pin_configure(drv_data->gpio, drv_cfg->power_gpios.pin,
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GPIO_OUTPUT_INACTIVE | drv_cfg->power_gpios.flags);
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if (rc != 0) {
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LOG_ERR("Failed to control feed %s.%u: %d", drv_cfg->power_gpios.label,
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drv_cfg->power_gpios.pin, rc);
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return rc;
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}
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}
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drv_data->as = (struct adc_sequence){
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.channels = BIT(0),
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.buffer = &drv_data->adc_raw,
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.buffer_size = sizeof(drv_data->adc_raw),
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.oversampling = 4,
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.calibrate = true,
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};
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#ifdef CONFIG_ADC_NRFX_SAADC
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drv_data->acc = (struct adc_channel_cfg){
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.gain = ADC_GAIN_1_5,
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.reference = ADC_REF_INTERNAL,
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.acquisition_time = ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 40),
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.input_positive = SAADC_CH_PSELP_PSELP_AnalogInput0 + drv_cfg->io_channel.channel,
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};
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drv_data->as.resolution = 12;
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#else
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#error Unsupported ADC
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#endif
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rc = adc_channel_setup(drv_data->adc, &drv_data->acc);
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LOG_DBG("AIN%u setup returned %d", drv_cfg->io_channel.channel, rc);
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return rc;
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}
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static struct bvd_data bvd_data;
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static const struct bvd_config bvd_cfg = {
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.io_channel =
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{
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DT_INST_IO_CHANNELS_LABEL(0),
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DT_INST_IO_CHANNELS_INPUT(0),
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},
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#if DT_INST_NODE_HAS_PROP(0, power_gpios)
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.power_gpios =
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{
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DT_INST_GPIO_LABEL(0, power_gpios),
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DT_INST_GPIO_PIN(0, power_gpios),
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DT_INST_GPIO_FLAGS(0, power_gpios),
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},
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#endif
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.output_ohm = DT_INST_PROP(0, output_ohms),
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.full_ohm = DT_INST_PROP(0, full_ohms),
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};
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DEVICE_AND_API_INIT(bvd_dev, DT_INST_LABEL(0), &bvd_init, &bvd_data, &bvd_cfg, POST_KERNEL,
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CONFIG_SENSOR_INIT_PRIORITY, &bvd_api);
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