SPI2 emulated TM1618 LED driver
USART1 debugging
+TIM3 TM1618 timeout
+TIM4 timing of IR remote control
Blue Pill pinout
| PB0 PA11 |
| PB1 PA10 | RXD1 - debugging console
| PB10 PA9 | TXD1 - debugging console
- | PB11 PA8 |
+ | PB11 PA8 | IR remote control
| RESET PB15 | MOSI2 - LED driver data input
| 3.3 V PB14 | MISO2 - unused
| GND PB13 | SCK2 - LED driver clock