Assignment of peripherals and pins
==================================

I2C1	display
USART1	debugging


			   Blue Pill pinout
			+--------------------+
			| VBATT		3.3V |
BluePill LED		| PC13		 GND |	display power
			| PC14		  5V |	display power (white side of connector)
			| PC15		 PB9 |
			| PA0		 PB8 |
			| PA1		 PB7 |	SDA1 display (white side of connector)
			| PA2		 PB6 |	SCL1 display
			| PA3		 PB5 |
			| PA4		 PB4 |
			| PA5		 PB3 |
			| PA6		PA15 |
			| PA7		PA12 |
			| PB0		PA11 |
			| PB1		PA10 |  RXD1 - debugging console
			| PB10		 PA9 |  TXD1 - debugging console
			| PB11		 PA8 |	SFH5110 output (white side of connector)
			| RESET		PB15 |
			| 3.3 V		PB14 |
			| GND		PB13 |
			| GND		PB12 |
			+--------------------+