Small overhaul

[KarlK90]

Hi @bstiq I have made some minor corrections to the schematics, mostly style stuff and added some explanations why things are needed. I have also added the schematics of the OG blackpill under docs. For reference these are the pin mappings that are DMA channel conflict free.

Pin No.	Pin	Function
11	PA1	TIM2_CH2 (RGB)
14	PA4	SPI1_NSS
15	PA5	SPI1_SCK
16	PA6	SPI1_MISO
17	PA7	SPI1_MOSI
30	PA9	USART1_TX (SERIAL)
32	PA11	USB_OTG_FS_DM
33	PA12	USB_OTG_FS_DP
42	PB6	I2C1_SCL
43	PB7	I2C1_SDA

DMA capabilities are needed for the WS2812 RGB LED driver in PWM mode. I have to check if this is also true for SPI and I2C (which is unused).

For reference the DMA channels used in this config:

Event	channel / stream
I2C1_RX	DMA1 Stream 0 (not needed atm)
I2C1_TX	DMA1 Stream 6 (not needed atm)
SPI1_RX	DMA2 Stream 0 (needed?)
SPI1_TX	DMA2 Stream 3 (needed?)
TIM2_UP	DMA1 Stream 1 (needed for WS2812 PWM driver)
USART1_RX	DMA2 Stream 2 (not needed QMK uses non-DMA driver)
USART1_TX	DMA2 Stream 7 (not needed QMK uses non-DMA driver)

Please note that the update event DMA channel is needed for the TIM2 timmer i.e. TIM2_UP not the channel events like TIM2_CH2.

Support for the SOIC-8 EEPROM is a good thing as QMK currently has no EEPROM emulation for the STM32F4 series.

On the support of Full-duplex, the transfer speed gains differences to Half-duplex are rather minor in practice so I wouldn't bother to much, also the the STM32F4 doesn't support TX/RX pin swapping in hardware so this would have to be done with solder jumpers which is a bit cumbersome.

[KarlK90]

I just pushed another update as I had forgotten that the Serial comms and Split Hand should be pulled up to 3.3V and only the RGB PWM pin has to be pulled up to 5V. I also included the datasheets and reference manuals for the MCUs that are used on the 2 versions of the blackpill. The pinout should be the same nevertheless.

[drashna]

Support for the SOIC-8 EEPROM is a good thing as QMK currently has no EEPROM emulation for the STM32F4 series.

That should no longer be true. F411 eeprom emulation should have been in develop and merged into master on the 27th.

qmk/qmk_firmware#14195

However, it's a bit of a mess, in the flash layout. So an SPI EEPROM chip is absolutely the way to go, here. Even with wear leveling in the fake eeprom, 4m writes vs 10-40k ....

DMA2 Stream 0 (needed?)

For the SPI stuff, yes, it's needed.

Also, I did need the DMA stream for full duplex serial.

[KarlK90]

Support for the SOIC-8 EEPROM is a good thing as QMK currently has no EEPROM emulation for the STM32F4 series.

That should no longer be true. F411 eeprom emulation should have been in develop and merged into master on the 27th.

qmk/qmk_firmware#14195

However, it's a bit of a mess, in the flash layout. So an SPI EEPROM chip is absolutely the way to go, here. Even with wear leveling in the fake eeprom, 4m writes vs 10-40k ....

Cool! Didn't follow that to closely.

DMA2 Stream 0 (needed?)

For the SPI stuff, yes, it's needed.

That is good to know, thanks! I'll add a readme to the repo.

Also, I did need the DMA stream for full duplex serial.

I know, but not anymore since qmk/qmk_firmware#13081 when I converted the full duplex back to the Chibios Serial driver.

[drashna]

I know, but not anymore since qmk/qmk_firmware#13081 when I converted the full duplex back to the Chibios Serial driver.

Even with that change, I had issues gettng it working on my blackpill till the dma channels were moved. But that may not have been the case, as there was a list of conflicts.