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Voltage divider driver initial implementation

xmkb
Nick 4 years ago
parent
commit
844f2c7674
  1. 10
      app/boards/arm/nice_nano/nice_nano.dts
  2. 4
      app/boards/arm/nice_nano/nice_nano_defconfig
  3. 1
      app/drivers/zephyr/CMakeLists.txt
  4. 115
      app/drivers/zephyr/battery_voltage_divider.c
  5. 9
      app/drivers/zephyr/dts/bindings/zmk,battery-voltage-divider.yaml

10
app/boards/arm/nice_nano/nice_nano.dts

@ -29,6 +29,16 @@
}; };
}; };
vbatt {
compatible = "zmk,battery-voltage-divider";
io-channels = <&adc 2>;
output-ohms = <2000000>;
full-ohms = <(2000000 + 806000)>;
};
};
&adc {
status = "okay";
}; };
&gpio0 { &gpio0 {

4
app/boards/arm/nice_nano/nice_nano_defconfig

@ -10,6 +10,10 @@ CONFIG_ARM_MPU=y
# enable GPIO # enable GPIO
CONFIG_GPIO=y CONFIG_GPIO=y
CONFIG_ADC=y
CONFIG_NEWLIB_LIBC=y
CONFIG_USE_DT_CODE_PARTITION=y CONFIG_USE_DT_CODE_PARTITION=y
CONFIG_MPU_ALLOW_FLASH_WRITE=y CONFIG_MPU_ALLOW_FLASH_WRITE=y

1
app/drivers/zephyr/CMakeLists.txt

@ -5,6 +5,7 @@ if(CONFIG_ZMK_KSCAN_GPIO_DRIVER)
zephyr_library_sources( zephyr_library_sources(
kscan_gpio_matrix.c kscan_gpio_matrix.c
kscan_gpio_direct.c kscan_gpio_direct.c
battery_voltage_divider.c
) )
zephyr_library_sources_ifdef(CONFIG_EC11 ec11.c) zephyr_library_sources_ifdef(CONFIG_EC11 ec11.c)

115
app/drivers/zephyr/battery_voltage_divider.c

@ -0,0 +1,115 @@
/*
* Copyright (c) 2020 The ZMK Contributors
*
* SPDX-License-Identifier: MIT
*/
#define DT_DRV_COMPAT zmk_battery_voltage_divider
#include <device.h>
#include <drivers/kscan.h>
#include <drivers/gpio.h>
#include <drivers/adc.h>
#include <drivers/sensor.h>
#include <logging/log.h>
#include <math.h>
LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
#if DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT)
#define VBATT DT_PATH(vbatt)
struct battery_config {
struct device *adc;
struct adc_channel_cfg acc;
struct adc_sequence as;
int16_t adc_raw;
};
static struct battery_config battery_config;
static int lithium_ion_mv_to_pct(int16_t bat_mv) {
// Magic function that maps mV to this discharge graph from adafruit: https://learn.adafruit.com/li-ion-and-lipoly-batteries/voltages
return round(106.818 + (-0.032685 - 106.818) / pow(1 + pow(bat_mv/3679.35, 58.979), 0.347386));
}
static void battery_read(struct k_work *workd) {
struct battery_config *cfg = &battery_config;
struct adc_sequence *as = &cfg->as;
int rc = adc_read(cfg->adc, as);
as->calibrate = false;
if (rc == 0) {
int32_t val = cfg->adc_raw;
adc_raw_to_millivolts(adc_ref_internal(cfg->adc), cfg->acc.gain, as->resolution, &val);
rc = val * (uint64_t)DT_PROP(VBATT, full_ohms) / DT_PROP(VBATT, output_ohms);
LOG_DBG("ADC raw %d ~ %d mV => %d mV\n", cfg->adc_raw, val, rc);
int percent = lithium_ion_mv_to_pct(rc);
LOG_DBG("Percent: %d", percent);
} else {
LOG_DBG("Failed to read ADC: %d", rc);
}
}
K_WORK_DEFINE(battery_work, battery_read);
static void battery_handler(struct k_timer *timer)
{
k_work_submit(&battery_work);
}
K_TIMER_DEFINE(battery_tick, battery_handler, NULL);
static int battery_setup(struct device *_arg) {
struct battery_config *cfg = &battery_config;
struct adc_sequence *as = &cfg->as;
struct adc_channel_cfg *acc = &cfg->acc;
cfg->adc = device_get_binding(DT_IO_CHANNELS_LABEL(VBATT));
if (cfg->adc == NULL) {
LOG_ERR("ADC %s failed to retrieve", DT_IO_CHANNELS_LABEL(VBATT));
return -ENOENT;
}
*as = (struct adc_sequence){
.channels = BIT(0),
.buffer = &cfg->adc_raw,
.buffer_size = sizeof(cfg->adc_raw),
.oversampling = 4,
.calibrate = true,
};
#ifdef CONFIG_ADC_NRFX_SAADC
*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 + DT_IO_CHANNELS_INPUT(VBATT),
};
as->resolution = 12;
#else
#error Unsupported ADC
#endif
int adc_rc = adc_channel_setup(cfg->adc, acc);
LOG_DBG("AIN%u setup returned %d", DT_IO_CHANNELS_INPUT(VBATT), adc_rc);
if (adc_rc != 0) {
return adc_rc;
}
k_timer_start(&battery_tick, K_NO_WAIT, K_SECONDS(5));
return 0;
}
SYS_INIT(battery_setup,
APPLICATION,
CONFIG_APPLICATION_INIT_PRIORITY);
#endif /* DT_HAS_COMPAT_STATUS_OKAY(DT_DRV_COMPAT) */

9
app/drivers/zephyr/dts/bindings/zmk,battery-voltage-divider.yaml

@ -0,0 +1,9 @@
# 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
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