mcp4725 v0.1.0

MCP4725 12-bit I2C digital-to-analog converter.

Application scenarios

• A 0..5 V setpoint for an analog circuit.
• Calibrating a sensor or actuator.
• A small waveform or bias source.

Contract

uint8_t mcp4725_init(mcp4725_t *device, mcp4725_port_t port, uint8_t i2c_address);
uint8_t mcp4725_write_value(mcp4725_t *device, uint16_t value);

• value is 0..4095; it updates the DAC register immediately.
• The output is value / 4096 * VDD (assuming VDD as reference).
• Returns 1 on success, 0 on a range error or a bus error.

Parameters

• I2C address 0x60..0x67.
• Power-down modes are not exposed; the normal mode is used.
• Keep the load within the output drive limit.

Memory and timing

• 4 bytes; one 2-byte I2C write.
• The output settles in a few microseconds.

Integration

mcp4725_t dac;
mcp4725_init(&dac, board_i2c_port(), 0x60);
mcp4725_write_value(&dac, 2048); /* about half scale */

Adapters

• The adapter issues the two-byte DAC command.
• Reference: LibDriver mcp4725 (MIT) and the Microchip MCP4725 datasheet.
• This implementation is original.

When not to use

• A PWM plus RC filter is sufficient.
• A current-output loop; use a current DAC.

Verification

make test covers a mid-scale write, full scale, zero, and range rejection.

void *context;
uint8_t (*write)(void *context, uint8_t address, const uint8_t *data, uint16_t length);

mcp4725_port_t port;
uint8_t i2c_address;