During testing and code inspection, there were various anti-patterns
on this (and U-Blox driver) codebase(s), including obfuscation, and
lack of data validation. This made it increasingly difficult to
introduce further variants of u-blox GNSS modems.
With this patch, both the UBX modem and the M8 driver have been
refactored to ease the reliability and maintainability of these
codebases. Here are some highlights:
WRT UBX modem:
- Helper macros to easily create UBX frames, (including checksum
calculation), at compile time; thus, making it easier to extend UBX
commands.
- Logic validation by the inclusion of the modem_ubx testsuite, used to
refactor the code through TDD.
- Ability to receive unsolicited messages, in order to enable U-Blox
drivers to rely on modem_ubx to transceive all commands, and avoid
hopping between modem_ubx and modem_chat.
WRT M8 driver:
- Remove GNSS specific protocol header files. Instead, unify them under
modem/ubx/protocol.h. Background: After a survey and looking at ubxlib
SDK I conclude the UBX protocol is by definition a GNSS protocol (there
are non-GNSS u-blox modems, but they're not interfaced through UBX
protocol).
- Establish pattern to create and send/receive commands using new
foundations on modem ubx.
- Remove dependency of Modem chat, and instead use UBX unsolicited
messages to get Navigation and Satellites data.
- Switch from the auto-baudrate detection pattern to a pattern of
transitioning between an initial known baudrate to a desired baudrate,
in order to improve initialization time.
- Add dts property to configure default fix-rate.
Signed-off-by: Luis Ubieda <luisf@croxel.com>
94a7f028ef