#![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.
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, waitingresponse, datamode)
- 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
The crate is covered by tests. These tests can be run by
cargo test --tests, and are run by the CI on every push.
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])
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:
cargo release --dry-run -- major|minor|patch, and verify the outputcargo release -- major|minor|patch, to releaseThe 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 | |