Update chibios README.

diff --git a/tmk_core/protocol/chibios/README.md b/tmk_core/protocol/chibios/README.md
index 5df4c6e77d3e3969294ce824dd1ccde0fea9a8ed..06569c51cb9303c1595f883bdb76e799c0027df5 100644 (file)
--- a/tmk_core/protocol/chibios/README.md
+++ b/tmk_core/protocol/chibios/README.md
@@ -1,12 +1,12 @@
-## USB stack implementation using ChibiOS
+## TMK running on top of ChibiOS
 
 ### Notes
 
-- To use, unpack or symlink ChibiOS here, to `chibios`.
-- For gcc options, inspect `chibios.mk`. For instance, I enabled `-Wno-missing-field-initializers`, because TMK common bits generated a lot of hits on that.
+- To use, unpack or symlink [ChibiOS] {currently 3.0.1} to `tmk_core/tool/chibios/chibios`.
+- 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.
 Also pay attention to `-O0` (enabled for debugging); for deployment use `-O2`.
-- USB string descriptors are a mess. 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.
-- There are some random constants left so far, e.g. 5ms sleep between calling `keyboard_task` in `main.c`. There should be no such in `usb_main.c`. Everything is based on timers/interrupts/kernel scheduling (well except `keyboard_task`), so no periodically called things (again, except `keyboard_task`, which is just how TMK is designed).
+- 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.
+- There are some random constants left so far, e.g. 5ms sleep between calling `keyboard_task`, or 1.5sec wait for USB init, in `main.c`. There should be no such in `usb_main.c` (the main USB stack). Everything is based on timers/interrupts/kernel scheduling (well except `keyboard_task`), so no periodically called things (again, except `keyboard_task`, which is just how TMK is designed).
 - 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 bootloader works, but it is not entirely pleasant, since it is very much MCU dependent. The code is now geared towards STM32 chips and their built-in bootloaders. So, one needs to dig out the right address to jump to, and pass it to the compiler in the `Makefile`. Also, a patch to upstream ChibiOS is needed (supplied), because it `ResetHandler` needs adjusting.
 - Sleep LED works, but at the moment only on/off, i.e. no breathing.
@@ -14,6 +14,7 @@ Also pay attention to `-O0` (enabled for debugging); for deployment use `-O2`.
 
 ### Immediate todo
 
+- host-wakeup packet sending during suspend
 - power saving for suspend?
 - PWM for sleep led
 
@@ -23,9 +24,27 @@ Also pay attention to `-O0` (enabled for debugging); for deployment use `-O2`.
 
 ### Missing / not working (TMK vs ChibiOS bits)
 
-- eeprom / bootmagic (will be chip dependent; eeprom needs to be emulated in flash, which means less writes; wear-levelling?)
+- eeprom / bootmagic (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
 
 - ChibiOS 3.0.1 and ST F072RB DISCOVERY board.
 - Need to test on other STM32 chips (F3, F4) to make it as much chip-independent as possible.
+
+## 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.
+- For breathing the caps lock LED during the suspended state ("sleep LED"), it is desirable to have that LED on a hardware PWM pin (there's usually plenty of those, look for TIMERs in the datasheet).
+
+## ChibiOS-supported MCUs (as of 3.0.1)
+
+- Pretty much all STM32 chips.
+- There is also support for AVR8, but the USB stack is not implemented for them yet, 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 some support for K20 and KL25 Freescale chips (i.e. Teensy 3.0, mchck, FRDM-KL25Z, FRDM-K20D50M), but again, no USB stack yet.
+- I've seen community support for Nordic NRF51822 (the chip in Adafruit's Bluefruit bluetooth-low-energy boards), but not sure about the extent.
+
+
+
+[ChibiOS]: http://chibios.org