qmk_firmware/tmk_core/protocol/chibios
Purdea Andrei dbd65d01b6
Fix how USB queue overflow is handled in chibios. (#12576)
* Fix how USB queue overflow is handled in chibios.

This commit reverts PR 12472 (commit c823fe2d3f23ed090e36ce39beed4c448298bd2f),
and it implements the original intent of the commit in a better way.
The original intent of the above mentioned commit was to not deadlock the
keyboard when console is enabled, and hid_listen is not started.

The above mentioned commit had a few drawbacks:
1) When a lot of data was printed to the console, the queue would get full,
and drop data, even if hid_listen was running. (For example having matrix debug
enabled just didn't work right at all)
2) I believe the function in which this was implemented is used by all other
USB endpoints, so with the above change, overflow, and data loss could
happen in other important functions of QMK as well.

This commit implements deadlock prevention in a slightly similar way to how
it's done on AVR. There is an additional static local variable, that memorizes
whether the console has timeouted before. If we are in the timeouted=false
state, then we send the character normally with a 5ms timeout. If it does
time out, then hid_listen is likely not running, and future characters should
not be sent with a timeout, but those characters should still be sent if there
is space in the queue. The difference between the AVR implementation and this
one is that the AVR implementation checks the queue state directly, but this
implementation instead attempts to write the character with a zero timeout.
If it fails, then we remain in the timeouted=true state, if it succeeds, then
hid_listen started removing data from the queue, so we can go out of the
timeouted=true state.

* Added comment explaining the timeouted logic to console flow control.

* Console flow control: refactor chibios flowcontrol code to make it more readable, and rename the timeouted variable to timed_out on both chibios and lufa. Changed comments to says timed_out is an approximation of listener_disconnected, to make it clear that it's not the same thing

* fix typo
2021-04-25 13:11:41 +10:00
..
lufa_utils/LUFA/Drivers/USB Normalise include statements in keyboard code (#11185) 2020-12-16 14:27:23 +11:00
init_hooks.h Add support for hardware and board initialisation overrides. (#8330) 2020-04-13 09:39:38 +10:00
main.c Decouple USB events from the USB interrupt handler. (#10437) 2021-02-01 08:19:00 +11:00
README.md
usb_driver.c Fix how USB queue overflow is handled in chibios. (#12576) 2021-04-25 13:11:41 +10:00
usb_driver.h Change include guards in tmk_core/ and drivers/ to pragma once (#11240) 2020-12-26 15:56:11 +11:00
usb_main.c Fix how USB queue overflow is handled in chibios. (#12576) 2021-04-25 13:11:41 +10:00
usb_main.h Decouple USB events from the USB interrupt handler. (#10437) 2021-02-01 08:19:00 +11:00

TMK running on top of ChibiOS

This code can be used to run TMK keyboard logic on top of ChibiOS, meaning that you can run TMK on whatever ChibiOS supports. The notable examples are ARM-based Teensies (3.x and LC) and on the boards with STM32 MCUs.

Usage

  • To use, get a zip of chibios and unpack/rename it to tmk_core/tool/chibios/chibios; or you can just clone the repo there. For Freescale/NXP Kinetis support (meaning ARM Teensies and the Infinity keyboard), you'll also need a zip of chibios-contrib, unpacked/renamed to tmk_core/tool/chibios/chibios-contrib. Likewise, for git-savvy people, just clone the repo there.
  • Note: the abovementioned directories are the defaults. You can have the two chibios repositories wherever you want, just define their location in CHIBIOS and CHIBIOS_CONTRIB variables in your Makefile.
  • You will also need to install an ARM toolchain, for instance from here. On linux, this is usually also present as a package for your distribution (as gcc-arm or something similar). On OS X, you can use homebrew with an appropriate tap.

Notes

  • Some comments about ChibiOS syntax and the most commonly used GPIO functions are, as well as an example for ARM Teensies, is here.
  • For gcc options, inspect tmk_core/tool/chibios/chibios.mk. For instance, I enabled -Wno-missing-field-initializers, because TMK common bits generated a lot of warnings on that.
  • For debugging, it is sometimes useful disable gcc optimisations, you can do that by adding -O0 to OPT_DEFS in your Makefile.
  • USB string descriptors are messy. I did not find a way to cleanly generate the right structures from actual strings, so the definitions in individual keyboards' config.h are ugly as heck.
  • It is easy to add some code for testing (e.g. blink LED, do stuff on button press, etc...) - just create another thread in main.c, it will run independently of the keyboard business.
  • Jumping to (the built-in) bootloaders on STM32 works, but it is not entirely pleasant, since it is very much MCU dependent. So, one needs to dig out the right address to jump to, and either pass it to the compiler in the Makefile, or better, define it in <your_kb>/bootloader_defs.h. An additional startup code is also needed; the best way to deal with this is to define custom board files. (Example forthcoming.) In any case, there are no problems for Teensies.

Immediate todo

  • power saving for suspend

Not tested, but possibly working

  • backlight

Missing / not working (TMK vs ChibiOS bits)

  • eeprom / bootmagic for STM32 (will be chip dependent; eeprom needs to be emulated in flash, which means less writes; wear-levelling?) There is a semi-official ST "driver" for eeprom, with wear-levelling, but I think it consumes a lot of RAM (like 2 pages, i.e. 1kB or so).

Tried with

  • Infinity, WhiteFox keyboards
  • all ARM-based Teensies
  • some STM32-based boards (e.g. ST-F072RB-DISCOVERY board, STM32F042 breakout board, Maple Mini (STM32F103-based))

ChibiOS-supported MCUs

  • Pretty much all STM32 chips.
  • K20x and KL2x Freescale/NXP chips (i.e. Teensy 3.x/LC, mchck, FRDM-KL2{5,6}Z, FRDM-K20D50M), via the ChibiOS-Contrib repository.
  • There is also support for AVR8, but the USB stack is not implemented for them yet (some news on that front recently though), and also the kernel itself takes about 1k of RAM. I think people managed to get ChibiOS running on atmega32[8p/u4] though.
  • There is also support for Nordic NRF51822 (the chip in Adafruit's Bluefruit bluetooth-low-energy boards), but be aware that that chip does not have USB, and the BLE softdevice (i.e. Bluetooth) is not supported directly at the moment.

STM32-based keyboard design considerations

  • STM32F0x2 chips can do crystal-less USB, but they still need a 3.3V voltage regulator.
  • The BOOT0 pin should be tied to GND.
  • For a hardware way of accessing the in-built DFU bootloader, in addition to the reset button, put another button between the BOOT0 pin and 3V3.
  • There is a working example of a STM32F042-based keyboard: firmware here and hardware (kicad) here. You can check this example firmware for custom board files, and a more complicated matrix than just one key.