149 lines
3.7 KiB
C
149 lines
3.7 KiB
C
/*
|
|
* 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, \
|
|
device_pm_control_nop, \
|
|
NULL, \
|
|
&mcp4725_config_##index, POST_KERNEL, \
|
|
CONFIG_DAC_MCP4725_INIT_PRIORITY, \
|
|
&mcp4725_driver_api);
|
|
|
|
DT_INST_FOREACH_STATUS_OKAY(INST_DT_MCP4725);
|