Merge pull request #293 from Nicell/bluetooth/battery-reporting

Add Battery Voltage Divider Driver

4 files changed, 236 insertions, 0 deletions

diff --git a/app/drivers/zephyr/CMakeLists.txt b/app/drivers/zephyr/CMakeLists.txt
index 8778ded..fc43fb8 100644
--- a/app/drivers/zephyr/CMakeLists.txt
+++ b/app/drivers/zephyr/CMakeLists.txt
@@ -9,4 +9,5 @@ if(CONFIG_ZMK_KSCAN_GPIO_DRIVER)
 
   zephyr_library_sources_ifdef(CONFIG_EC11 ec11.c)
   zephyr_library_sources_ifdef(CONFIG_EC11_TRIGGER ec11_trigger.c)
+  zephyr_library_sources_ifdef(CONFIG_ZMK_BATTERY_VOLTAGE_DIVIDER battery_voltage_divider.c)
 endif()
diff --git a/app/drivers/zephyr/Kconfig b/app/drivers/zephyr/Kconfig
index 0534cab..6b177fb 100644
--- a/app/drivers/zephyr/Kconfig
+++ b/app/drivers/zephyr/Kconfig
@@ -21,6 +21,12 @@ config ZMK_KSCAN_INIT_PRIORITY
 	help
 	  Keyboard scan device driver initialization priority.
 
+config ZMK_BATTERY_VOLTAGE_DIVIDER
+	bool "ZMK battery voltage divider"
+	select ADC
+	help
+		Enable ZMK battery voltage divider driver for battery monitoring.
+
 menuconfig EC11
 	bool "EC11 Incremental Encoder Sensor"
 	depends on GPIO
diff --git a/app/drivers/zephyr/battery_voltage_divider.c b/app/drivers/zephyr/battery_voltage_divider.c
new file mode 100644
index 0000000..37ac024
--- /dev/null
+++ b/app/drivers/zephyr/battery_voltage_divider.c
@@ -0,0 +1,215 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#define DT_DRV_COMPAT zmk_battery_voltage_divider
+
+#include <device.h>
+#include <drivers/gpio.h>
+#include <drivers/adc.h>
+#include <drivers/sensor.h>
+#include <logging/log.h>
+
+LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
+
+struct io_channel_config {
+    const char *label;
+    uint8_t channel;
+};
+
+struct gpio_channel_config {
+    const char *label;
+    uint8_t pin;
+    uint8_t flags;
+};
+
+struct bvd_config {
+    struct io_channel_config io_channel;
+    struct gpio_channel_config power_gpios;
+    uint32_t output_ohm;
+    uint32_t full_ohm;
+};
+
+struct bvd_data {
+    struct device *adc;
+    struct device *gpio;
+    struct adc_channel_cfg acc;
+    struct adc_sequence as;
+    uint16_t adc_raw;
+    uint16_t voltage;
+    uint8_t state_of_charge;
+};
+
+static uint8_t lithium_ion_mv_to_pct(int16_t bat_mv) {
+    // Simple linear approximation of a battery based off adafruit's discharge graph:
+    // https://learn.adafruit.com/li-ion-and-lipoly-batteries/voltages
+
+    if (bat_mv >= 4200) {
+        return 100;
+    } else if (bat_mv <= 3450) {
+        return 0;
+    }
+
+    return bat_mv * 2 / 15 - 459;
+}
+
+static int bvd_sample_fetch(struct device *dev, enum sensor_channel chan) {
+    struct bvd_data *drv_data = dev->driver_data;
+    const struct bvd_config *drv_cfg = dev->config_info;
+    struct adc_sequence *as = &drv_data->as;
+
+    // Make sure selected channel is supported
+    if (chan != SENSOR_CHAN_GAUGE_VOLTAGE && chan != SENSOR_CHAN_GAUGE_STATE_OF_CHARGE) {
+        return -ENOTSUP;
+    }
+
+    int rc = 0;
+
+    // Enable power GPIO if present
+    if (drv_data->gpio) {
+        rc = gpio_pin_set(drv_data->gpio, drv_cfg->power_gpios.pin, 1);
+
+        if (rc != 0) {
+            LOG_DBG("Failed to enable ADC power GPIO: %d", rc);
+            return rc;
+        }
+    }
+
+    // Read ADC
+    rc = adc_read(drv_data->adc, as);
+    as->calibrate = false;
+
+    if (rc == 0) {
+        int32_t val = drv_data->adc_raw;
+
+        adc_raw_to_millivolts(adc_ref_internal(drv_data->adc), drv_data->acc.gain, as->resolution,
+                              &val);
+
+        uint16_t millivolts = val * (uint64_t)drv_cfg->full_ohm / drv_cfg->output_ohm;
+        LOG_DBG("ADC raw %d ~ %d mV => %d mV\n", drv_data->adc_raw, val, millivolts);
+        uint8_t percent = lithium_ion_mv_to_pct(millivolts);
+        LOG_DBG("Percent: %d", percent);
+
+        drv_data->voltage = millivolts;
+        drv_data->state_of_charge = percent;
+    } else {
+        LOG_DBG("Failed to read ADC: %d", rc);
+    }
+
+    // Disable power GPIO if present
+    if (drv_data->gpio) {
+        int rc2 = gpio_pin_set(drv_data->gpio, drv_cfg->power_gpios.pin, 0);
+
+        if (rc2 != 0) {
+            LOG_DBG("Failed to disable ADC power GPIO: %d", rc2);
+            return rc2;
+        }
+    }
+
+    return rc;
+}
+
+static int bvd_channel_get(struct device *dev, enum sensor_channel chan, struct sensor_value *val) {
+    struct bvd_data *drv_data = dev->driver_data;
+
+    switch (chan) {
+    case SENSOR_CHAN_GAUGE_VOLTAGE:
+        val->val1 = drv_data->voltage / 1000;
+        val->val2 = (drv_data->voltage % 1000) * 1000U;
+        break;
+
+    case SENSOR_CHAN_GAUGE_STATE_OF_CHARGE:
+        val->val1 = drv_data->state_of_charge;
+        val->val2 = 0;
+        break;
+
+    default:
+        return -ENOTSUP;
+    }
+
+    return 0;
+}
+
+static const struct sensor_driver_api bvd_api = {
+    .sample_fetch = bvd_sample_fetch,
+    .channel_get = bvd_channel_get,
+};
+
+static int bvd_init(struct device *dev) {
+    struct bvd_data *drv_data = dev->driver_data;
+    const struct bvd_config *drv_cfg = dev->config_info;
+
+    drv_data->adc = device_get_binding(drv_cfg->io_channel.label);
+
+    if (drv_data->adc == NULL) {
+        LOG_ERR("ADC %s failed to retrieve", drv_cfg->io_channel.label);
+        return -ENODEV;
+    }
+
+    int rc = 0;
+
+    if (drv_cfg->power_gpios.label) {
+        drv_data->gpio = device_get_binding(drv_cfg->power_gpios.label);
+        if (drv_data->gpio == NULL) {
+            LOG_ERR("Failed to get GPIO %s", drv_cfg->power_gpios.label);
+            return -ENODEV;
+        }
+        rc = gpio_pin_configure(drv_data->gpio, drv_cfg->power_gpios.pin,
+                                GPIO_OUTPUT_INACTIVE | drv_cfg->power_gpios.flags);
+        if (rc != 0) {
+            LOG_ERR("Failed to control feed %s.%u: %d", drv_cfg->power_gpios.label,
+                    drv_cfg->power_gpios.pin, rc);
+            return rc;
+        }
+    }
+
+    drv_data->as = (struct adc_sequence){
+        .channels = BIT(0),
+        .buffer = &drv_data->adc_raw,
+        .buffer_size = sizeof(drv_data->adc_raw),
+        .oversampling = 4,
+        .calibrate = true,
+    };
+
+#ifdef CONFIG_ADC_NRFX_SAADC
+    drv_data->acc = (struct adc_channel_cfg){
+        .gain = ADC_GAIN_1_5,
+        .reference = ADC_REF_INTERNAL,
+        .acquisition_time = ADC_ACQ_TIME(ADC_ACQ_TIME_MICROSECONDS, 40),
+        .input_positive = SAADC_CH_PSELP_PSELP_AnalogInput0 + drv_cfg->io_channel.channel,
+    };
+
+    drv_data->as.resolution = 12;
+#else
+#error Unsupported ADC
+#endif
+
+    rc = adc_channel_setup(drv_data->adc, &drv_data->acc);
+    LOG_DBG("AIN%u setup returned %d", drv_cfg->io_channel.channel, rc);
+
+    return rc;
+}
+
+static struct bvd_data bvd_data;
+static const struct bvd_config bvd_cfg = {
+    .io_channel =
+        {
+            DT_INST_IO_CHANNELS_LABEL(0),
+            DT_INST_IO_CHANNELS_INPUT(0),
+        },
+#if DT_INST_NODE_HAS_PROP(0, power_gpios)
+    .power_gpios =
+        {
+            DT_INST_GPIO_LABEL(0, power_gpios),
+            DT_INST_PIN(0, power_gpios),
+            DT_INST_FLAGS(0, power_gpios),
+        },
+#endif
+    .output_ohm = DT_INST_PROP(0, output_ohms),
+    .full_ohm = DT_INST_PROP(0, full_ohms),
+};
+
+DEVICE_AND_API_INIT(bvd_dev, DT_INST_LABEL(0), &bvd_init, &bvd_data, &bvd_cfg, POST_KERNEL,
+                    CONFIG_SENSOR_INIT_PRIORITY, &bvd_api);
diff --git a/app/drivers/zephyr/dts/bindings/zmk,battery-voltage-divider.yaml b/app/drivers/zephyr/dts/bindings/zmk,battery-voltage-divider.yaml
new file mode 100644
index 0000000..3f391d7
--- /dev/null
+++ b/app/drivers/zephyr/dts/bindings/zmk,battery-voltage-divider.yaml
@@ -0,0 +1,14 @@
+# Copyright (c) 2020 The ZMK Contributors
+# SPDX-License-Identifier: MIT
+
+description: Battery SoC monitoring using voltage divider
+
+compatible: "zmk,battery-voltage-divider"
+
+include: voltage-divider.yaml
+
+properties:
+  label:
+    required: true
+    type: string
+  
\ No newline at end of file