The orientation of the board is seen as the Micro-USB being at the top.

Location Pin Functions
J2, bottom pin PA10 Interrupt, I2C1_SDA, USART1_RX
J2, left pin GND  
J2, right, top pin PA9 Interrupt, I2C1_SCL, USART1_TX
PIR, left, top pin PB14 Interrupt,
PIR, right, top pin PA2 ADC2, USART2_TX
PIR, left, bottom pin PA3 Interrupt, ADC3, USART2_RX
PIR, right, bottom pin GND  

Note: Keep in mind when using I2C on these pins that the internal senors are utilizing the same bus with different GPIO pins (PB8-I2C1_SCL/PB9-I2C1_SDA). Trying to use the same bus on different pins at the same time might cause issues during initialization.


This is a view from the bottom of the board. The pin names are also displayed on the silk screen of the board.