ATAT

#![no_std] crate for parsing AT commands (Hayes command set)

A driver support crate for AT-command based serial modules, using the embedded-hal traits.

AT Best practices

This crate attempts to work from these AT best practices:

• The DTE shall flush the AT channel (i.e. check if there are data waiting to be read) before sending a new AT command
• The DTE shall detect/process complete lines (see the S3, S4 and V0/V1 settings), so they can be processed with a function that handles responses
• The DTE shall handle the case of unexpected spaces or line endings
• The DTE shall handle all the URCs: it can simply ignore them (not suggested) or, better, take a proper action
• The DTE shall know what answer is expected and shall wait until it is received (i.e. final result code only or informationtext response + final result code)
• The final result code marks the end of an AT command and can be OK, ERROR or ABORTED: when the final result is an error, be sure to handle it before continuing with the next AT command
• The information text response format is command specific. The DTE will need explicit handling for each one. It is suggested to consult the u-blox AT Commands Manual [1]
• It is suggested not to strictly parse information text responses but to checkif they contain interesting keywords and/or parameters
• The DTE shall know if the issued AT command can be aborted or not
• Some AT commands could output the final result code after some seconds, in this case check on AT manual for the suggested estimated response time. If the timeout expires then a decision should be taken accordingly: e.g. if the command can be aborted then try to abort it, etc ...
• It is very useful, for debugging an application, to log all the command lines sent to the DCE and what is received from it
• Create a state machine for the AT parser (i.e. idle, waiting_response, data_mode)
• The DTE shall wait some time (the recommended value is at least 20 ms) after the reception of an AT command final response or URC before issuing a new AT commandto give the module the opportunity to transmit the buffered URCs. Otherwise the collision of the URCs with the subsequent AT command is still possible
• The DTE shall be aware that, when using a serial port without HW flow control, the first character is used to wake up the module from power saving

Documentation

Tests

The crate is covered by tests. These tests can be run by cargo test --tests, and are run by the CI on every push.

Examples

The crate has examples for usage with cortex-m-rt and cortex-m-rtic crates.

The samples can be built using cargo build --example cortex-m-rt --target thumbv7em-none-eabihf and cargo build --example rtic --target thumbv7em-none-eabihf.

Furthermore I have used the crate to build initial WIP drivers for uBlox cellular modules (ublox-cellular-rs) and uBlox short-range modules (ublox-short-range-rs)

Releasing to crates.io

This workspace uses cargo-release to do workspace releases to crates.io. It can be installed through cargo with cargo install cargo-release. The steps involved in a new release are:

1. Run cargo release --dry-run -- major|minor|patch, and verify the output
2. Run cargo release -- major|minor|patch, to release

About

• Minimum rustc version 1.52
• Tested and built using stable toolchain

Supported Crates

The following dependent crates provide platform-agnostic device drivers built on embedded-hal which also implement this crate's traits:

Device Name	Description	Crate + Docs
ublox-short-range-rs	Driver crate for U-Blox host-based short range devices (wifi and BT) with AT-command interface
ublox-cellular-rs	Driver crate for U-Blox host-based cellular devices with AT-command interface
espresso	AT based driver crate for ESP8266 WiFi modules

Features

• derive: Enabled by default. Re-exports atat_derive to allow deriving Atat__ traits.
• bytes: Enabled by default. Re-exports serde-bytes & heapless-bytes to allow serializing & deserializing non-quoted byte slices correctly.
• log: Disabled by default. Enable log statements on various log levels to aid debugging. Powered by log.
• defmt: Disabled by default. Enable defmt log statements on various log levels to aid debugging. Powered by defmt.
• custom-error-messages: Disabled by default. Allows errors to contain custom error messages up to 64 characters, parsed by AtDigest::custom_error.

Chat / Getting Help

If you have questions on the development of AT-AT or want to write a driver based on it, feel free to join our matrix room at #atat:matrix.org!

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.