182 lines
4.5 KiB
C
182 lines
4.5 KiB
C
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/**
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* Driver for AD7705/AD7706 SPI ADC
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*
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* Part of esp-open-rtos
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* Copyright (C) 2017 Ruslan V. Uss <unclerus@gmail.com>
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* BSD Licensed as described in the file LICENSE
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*/
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#include "ad770x.h"
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#include <errno.h>
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#include <esp/gpio.h>
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#include <esp/spi.h>
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#include <espressif/esp_common.h>
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#define AD770X_DEBUG
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#define BUS 1
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#define INIT_TIMEOUT 500000 // 500ms
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#ifdef AD770X_DEBUG
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#include <stdio.h>
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#define debug(fmt, ...) printf("%s" fmt "\n", "AD770x: ", ## __VA_ARGS__)
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#else
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#define debug(fmt, ...)
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#endif
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#define timeout_expired(start, len) ((uint32_t)(sdk_system_get_time() - (start)) >= (len))
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#define _BV(x) (1 << (x))
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#define REG_COMM 0x00 // 8 bits
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#define REG_SETUP 0x01 // 8 bits
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#define REG_CLOCK 0x02 // 8 bits
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#define REG_DATA 0x03 // 16 bits
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#define REG_TEST 0x04 // 8 bits
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#define REG_OFFS 0x06 // 24 bits
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#define REG_GAIN 0x07 // 24 bits
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#define BIT_COMM_CH0 0
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#define BIT_COMM_CH1 1
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#define BIT_COMM_STBY 2
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#define BIT_COMM_RW 3
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#define BIT_COMM_RS0 4
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#define BIT_COMM_RS1 5
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#define BIT_COMM_RS2 6
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#define BIT_COMM_DRDY 7
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#define MASK_COMM_CH 0x03
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#define MASK_COMM_RS 0x70
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#define BIT_CLOCK_FS0 0
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#define BIT_CLOCK_FS1 1
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#define BIT_CLOCK_CLK 2
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#define BIT_CLOCK_CLKDIV 3
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#define BIT_CLOCK_CLKDIS 4
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#define MASK_CLOCK_FS 0x03
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#define MASK_CLOCK_CLK 0x0c
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#define BIT_SETUP_FSYNC 0
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#define BIT_SETUP_BUF 1
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#define BIT_SETUP_BU 2
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#define BIT_SETUP_G0 3
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#define BIT_SETUP_G1 4
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#define BIT_SETUP_G2 5
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#define BIT_SETUP_MD0 6
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#define BIT_SETUP_MD1 7
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#define MASK_SETUP_GAIN 0x38
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#define MASK_SETUP_MODE 0xc0
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static const spi_settings_t config = {
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.endianness = SPI_BIG_ENDIAN,
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.msb = true,
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.minimal_pins = true,
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.mode = SPI_MODE3,
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.freq_divider = SPI_FREQ_DIV_500K
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};
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static uint8_t write(uint8_t cs_pin, uint8_t value)
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{
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spi_settings_t old;
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spi_get_settings(BUS, &old);
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spi_set_settings(BUS, &config);
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gpio_write(cs_pin, false);
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uint8_t res = spi_transfer_8(BUS, value);
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//debug("byte wr: 0x%02x", value);
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gpio_write(cs_pin, true);
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spi_set_settings(BUS, &old);
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return res;
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}
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inline static uint8_t read_byte(uint8_t cs_pin)
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{
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return write(cs_pin, 0);
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}
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static uint16_t read_word(uint8_t cs_pin)
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{
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spi_settings_t old;
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spi_get_settings(BUS, &old);
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spi_set_settings(BUS, &config);
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gpio_write(cs_pin, false);
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uint16_t res = spi_transfer_16(BUS, 0);
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gpio_write(cs_pin, true);
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spi_set_settings(BUS, &old);
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return res;
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}
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static void prepare(uint8_t channel, uint8_t reg, bool read, uint8_t cs_pin, bool standby)
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{
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write(cs_pin,
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(channel & MASK_COMM_CH) |
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(read ? _BV(BIT_COMM_RW) : 0) |
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((reg << BIT_COMM_RS0) & MASK_COMM_RS) |
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(standby ? _BV(BIT_COMM_STBY) : 0)
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);
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}
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int ad770x_init(const ad770x_params_t *params, uint8_t channel)
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{
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if (!spi_set_settings(BUS, &config))
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{
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debug("Cannot init SPI");
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return -EIO;
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}
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if ((params->master_clock >= AD770X_MCLK_2_4576MHz && params->update_rate < AD770X_RATE_50)
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|| (params->master_clock < AD770X_MCLK_2_4576MHz && params->update_rate > AD770X_RATE_200))
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{
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debug("Invalid update rate / master clock combination");
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return -EINVAL;
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}
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gpio_enable(params->cs_pin, GPIO_OUTPUT);
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gpio_write(params->cs_pin, true);
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prepare(channel, REG_CLOCK, false, params->cs_pin, false);
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write(params->cs_pin,
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((params->master_clock << BIT_CLOCK_CLK) & MASK_CLOCK_CLK) |
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(params->update_rate & MASK_CLOCK_FS)
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);
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ad770x_set_mode(params, channel, AD770X_MODE_CALIBRATION);
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uint32_t start = sdk_system_get_time();
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while (!ad770x_data_ready(params, channel))
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if (timeout_expired(start, INIT_TIMEOUT))
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{
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debug("Timeout while calibration");
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return -EIO;
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}
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return 0;
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}
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void ad770x_set_mode(const ad770x_params_t *params, uint8_t channel, ad770x_mode_t mode)
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{
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prepare(channel, REG_SETUP, false, params->cs_pin, false);
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write(params->cs_pin,
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((params->gain << BIT_SETUP_G0) & MASK_SETUP_GAIN) |
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(params->bipolar ? 0 : _BV(BIT_SETUP_BU)) |
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((mode << BIT_SETUP_MD0) & MASK_SETUP_MODE)
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);
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}
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bool ad770x_data_ready(const ad770x_params_t *params, uint8_t channel)
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{
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prepare(channel, REG_COMM, true, params->cs_pin, false);
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return !(read_byte(params->cs_pin) & _BV(BIT_COMM_DRDY));
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}
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uint16_t ad770x_raw_adc_value(const ad770x_params_t *params, uint8_t channel)
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{
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prepare(channel, REG_DATA, true, params->cs_pin, false);
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return read_word(params->cs_pin);
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}
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