current_sense_amplifier.h

Go to the documentation of this file.

/*
 * Copyright (c) 2023 The ChromiumOS Authors
 *
 * SPDX-License-Identifier: Apache-2.0
 */
 
#ifndef ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_AMPLIFIER_H_
#define ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_AMPLIFIER_H_
 
#include <zephyr/drivers/adc.h>
#include <zephyr/drivers/gpio.h>
 
struct current_sense_amplifier_dt_spec {
        const struct adc_dt_spec port;
        uint32_t sense_micro_ohms;
        uint32_t sense_gain_mult;
        uint32_t sense_gain_div;
        struct gpio_dt_spec power_gpio;
};
 
#define CURRENT_SENSE_AMPLIFIER_DT_SPEC_GET(node_id)                                               \
        {                                                                                          \
                .port = ADC_DT_SPEC_GET(node_id),                                                  \
                .sense_micro_ohms = DT_PROP(node_id, sense_resistor_micro_ohms),                   \
                .sense_gain_mult = DT_PROP(node_id, sense_gain_mult),                              \
                .sense_gain_div = DT_PROP(node_id, sense_gain_div),                                \
                .power_gpio = GPIO_DT_SPEC_GET_OR(node_id, power_gpios, {0}),                      \
        }
 
static inline void
current_sense_amplifier_scale_dt(const struct current_sense_amplifier_dt_spec *spec,
                                 int32_t *v_to_i)
{
        /* store in a temporary 64 bit variable to prevent overflow during calculation */
        int64_t tmp = *v_to_i;
 
        /* multiplies by 1,000,000 before dividing by sense resistance in micro-ohms. */
        tmp = tmp * 1000000 / spec->sense_micro_ohms * spec->sense_gain_div / spec->sense_gain_mult;
 
        *v_to_i = (int32_t)tmp;
}
 
#endif /* ZEPHYR_INCLUDE_DRIVERS_ADC_CURRENT_SENSE_AMPLIFIER_H_ */