Rust driver for MCP4728 4-channel 12-bit I2C DAC

This is a platform agnostic rust driver for the MCP4728 DAC using the embedded-hal traits.

This driver allows you to:

• Write to a single channel and save to EEPROM
• Write to multiple channels and save to EEPROM
• Write to all channels, skipping some configuration bits and not saving to EEPROM ("fast write")
• Write voltage reference mode to all channels
• Write gain mode to all channels
• Write power down mode to all channels
• Read EEPROM and output registers for all channels
• Issue I2C General Call commands: reset, wake up, and software update

There is one feature that this driver does not support - reading and writing the I2C address of the device. Three bits of the driver can be set (from 0x60 to 0x67) but this is done by toggling another pin in precise timing with the I2C message, which is not possible to do using the embedded-hal traits.

This crate is #![no_std] and does not contain unsafe code.

Device

The MCP4728 is a 4-channel, 12-bit digital-to-analog converter with nonvolatile memory (EEPROM) for its output settings. The device will load its previous setting from EEPROM on startup without receiving any commands. Each channel has separate voltage reference, gain, and power down settings. Channels can be written individually or together.

Datasheet

MCP4728

Features

• sync: Adds support for the embedded-hal I2c trait (enabled by default)
• async: Adds support for the embedded-hal-async I2c trait
• defmt: Adds implementation of the defmt Format trait to all types

Usage

use linux_embedded_hal::I2cdev;
use mcp4728::{MCP4728};

let i2c = I2cdev::new("/dev/i2c-1").unwrap();
let mut dac = MCP4728::new(i2c, 0x60);
dac.fast_write(483, 279, 297, 590).unwrap();

Updating the analog outputs

Most commands write to the output register but do not necessarily update the analog output. There are several ways to do so:

• If OutputEnableMode is Update, the output will be updated after the last byte is received for each channel (not all commands can set this bit)
• If the LDAC pin is set low, the output will be updated after the last byte is received for each channel.
• If the LDAC pin transitions from high to low at any time, all channels will be updated.
• If a General Call Software Update command is received, all channels will be updated.

Async

This crate optionally supports async, behind the async feature. The API is otherwise identical.

use mcp4728::{MCP4728Async};

// Assume i2c implements embedded_hal_async::i2c::I2c.
let mut dac = MCP4728Async::new(i2c, 0x60);
dac.fast_write(483, 279, 297, 590).await.unwrap();

Minimum Supported Rust Version (MSRV)

This crate is guaranteed to compile on stable Rust 1.75 and up. It might compile with older versions but that may change in any new patch release.

License

Licensed under either of

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.