blob: 0de3e1dd874f1a667f628c0ad3b6a33dc79f0ab6 [file] [log] [blame]
/*
* Copyright (c) 2021 Laird Connectivity
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT microchip_mcp4725
#include <zephyr.h>
#include <drivers/i2c.h>
#include <drivers/dac.h>
#include <logging/log.h>
LOG_MODULE_REGISTER(dac_mcp4725, CONFIG_DAC_LOG_LEVEL);
/* Information in this file comes from MCP4725 datasheet revision D
* found at https://ww1.microchip.com/downloads/en/DeviceDoc/22039d.pdf
*/
/* Defines for field values in MCP4725 DAC register */
#define MCP4725_DAC_MAX_VAL 0xFFF
#define MCP4725_FAST_MODE_POWER_DOWN_POS 4U
#define MCP4725_FAST_MODE_DAC_UPPER_VAL_POS 8U
#define MCP4725_FAST_MODE_DAC_UPPER_VAL_MASK 0xF
#define MCP4725_FAST_MODE_DAC_LOWER_VAL_MASK 0xFF
#define MCP4725_READ_RDY_POS 7U
#define MCP4725_READ_RDY_MASK (0x1 << MCP4725_READ_RDY_POS)
/* After writing eeprom, the MCP4725 can be in a busy state for 25 - 50ms
* See section 1.0 of MCP4725 datasheet, 'Electrical Characteristics'
*/
#define MCP4725_BUSY_TIMEOUT_MS 60U
struct mcp4725_config {
const struct device *i2c_dev;
uint16_t i2c_addr;
};
/* Read mcp4725 and check RDY status bit */
static int mcp4725_wait_until_ready(const struct device *dev, uint16_t i2c_addr)
{
uint8_t rx_data[5];
bool mcp4725_ready = false;
int ret;
int32_t timeout = k_uptime_get_32() + MCP4725_BUSY_TIMEOUT_MS;
/* Wait until RDY bit is set or return error if timer exceeds MCP4725_BUSY_TIMEOUT_MS */
while (!mcp4725_ready) {
ret = i2c_read(dev, rx_data, sizeof(rx_data), i2c_addr);
if (ret == 0) {
mcp4725_ready = rx_data[0] & MCP4725_READ_RDY_MASK;
} else {
/* I2C error */
return ret;
}
if (k_uptime_get_32() > timeout) {
return -ETIMEDOUT;
}
}
return 0;
}
/* MCP4725 is a single channel 12 bit DAC */
static int mcp4725_channel_setup(const struct device *dev,
const struct dac_channel_cfg *channel_cfg)
{
if (channel_cfg->channel_id != 0) {
return -EINVAL;
}
if (channel_cfg->resolution != 12) {
return -ENOTSUP;
}
return 0;
}
static int mcp4725_write_value(const struct device *dev, uint8_t channel,
uint32_t value)
{
const struct mcp4725_config *config = (struct mcp4725_config *)dev->config;
uint8_t tx_data[2];
int ret;
if (channel != 0) {
return -EINVAL;
}
/* Check value isn't over 12 bits */
if (value > MCP4725_DAC_MAX_VAL) {
return -ENOTSUP;
}
/* WRITE_MODE_FAST message format (2 bytes):
*
* || 15 14 | 13 12 | 11 10 9 8 || 7 6 5 4 3 2 1 0 ||
* || Fast mode (0) | Power-down bits (0) | DAC value[11:8] || DAC value[7:0] ||
*/
tx_data[0] = ((value >> MCP4725_FAST_MODE_DAC_UPPER_VAL_POS) &
MCP4725_FAST_MODE_DAC_UPPER_VAL_MASK);
tx_data[1] = (value & MCP4725_FAST_MODE_DAC_LOWER_VAL_MASK);
ret = i2c_write(config->i2c_dev, tx_data, sizeof(tx_data),
config->i2c_addr);
return ret;
}
static int dac_mcp4725_init(const struct device *dev)
{
const struct mcp4725_config *config = dev->config;
if (!device_is_ready(config->i2c_dev)) {
LOG_ERR("I2C device not found");
return -EINVAL;
}
/* Check we can read a 'RDY' bit from this device */
if (mcp4725_wait_until_ready(config->i2c_dev, config->i2c_addr)) {
return -EBUSY;
}
return 0;
}
static const struct dac_driver_api mcp4725_driver_api = {
.channel_setup = mcp4725_channel_setup,
.write_value = mcp4725_write_value,
};
#define INST_DT_MCP4725(index) \
static const struct mcp4725_config mcp4725_config_##index = { \
.i2c_dev = DEVICE_DT_GET(DT_INST_BUS(index)), \
.i2c_addr = DT_INST_REG_ADDR(index) \
}; \
\
DEVICE_DT_INST_DEFINE(index, dac_mcp4725_init, \
NULL, \
NULL, \
&mcp4725_config_##index, POST_KERNEL, \
CONFIG_DAC_MCP4725_INIT_PRIORITY, \
&mcp4725_driver_api);
DT_INST_FOREACH_STATUS_OKAY(INST_DT_MCP4725);