Appendix B: Pin Reference — STM32H743VIT6

This appendix lists the most commonly used peripheral pin mappings for the STM32H743VIT6 in the LQFP-100 package. All alternate function (AF) numbers are from the official datasheet (DS12110). When configuring Embassy, you specify the pin and Embassy selects the correct AF automatically — but knowing the AF number helps when reading the datasheet or debugging.

SPI1

Function	Pin Option 1	AF	Pin Option 2	AF	Notes
SCK	PA5	AF5	PB3	AF5	Clock
MOSI	PA7	AF5	PD7	AF5	Master Out Slave In
MISO	PA6	AF5	PB4	AF5	Master In Slave Out
NSS	PA4	AF5	PA15	AF5	Chip select (usually manual GPIO)

SPI2

Function	Pin Option 1	AF	Pin Option 2	AF	Notes
SCK	PB10	AF5	PB13	AF5	Clock
MOSI	PB15	AF5	PC3	AF5	Master Out Slave In
MISO	PB14	AF5	PC2	AF5	Master In Slave Out
NSS	PB9	AF5	PB12	AF5	Chip select

I2C1

Function	Pin Option 1	AF	Pin Option 2	AF	Notes
SCL	PB6	AF4	PB8	AF4	Clock — needs 4.7k pull-up to 3.3V
SDA	PB7	AF4	PB9	AF4	Data — needs 4.7k pull-up to 3.3V

I2C2

Function	Pin Option 1	AF	Pin Option 2	AF	Notes
SCL	PB10	AF4	PH4	AF4	Clock
SDA	PB11	AF4	PH5	AF4	Data

Think About It: PB10 appears in both the SPI2 and I2C2 tables. A pin can only serve one alternate function at a time. If you need both SPI2 and I2C2, pick non-conflicting pin options.

USART1

Function	Pin Option 1	AF	Pin Option 2	AF	Notes
TX	PA9	AF7	PB6	AF7	Transmit
RX	PA10	AF7	PB7	AF7	Receive
CTS	PA11	AF7	—	—	Clear to send (flow control)
RTS	PA12	AF7	—	—	Request to send (flow control)

USART2

Function	Pin Option 1	AF	Pin Option 2	AF	Notes
TX	PA2	AF7	PD5	AF7	Transmit
RX	PA3	AF7	PD6	AF7	Receive

Fun Fact: On Nucleo-144 boards, USART3 (PD8/PD9) is typically connected to the ST-Link's virtual COM port. This is the UART you see when you open a serial terminal over USB, even though the STM32 itself is using USART3 — not USB.

TIM1 (Advanced Timer — PWM Capable)

Function	Pin Option 1	AF	Pin Option 2	AF	Notes
CH1	PA8	AF1	PE9	AF1	PWM output 1
CH2	PA9	AF1	PE11	AF1	PWM output 2
CH3	PA10	AF1	PE13	AF1	PWM output 3
CH4	PA11	AF1	PE14	AF1	PWM output 4
CH1N	PA7	AF1	PB13	AF1	Complementary output 1
CH2N	PB0	AF1	PB14	AF1	Complementary output 2
CH3N	PB1	AF1	PB15	AF1	Complementary output 3

ADC1 Channels

Channel	Pin	Notes
IN0	PA0	—
IN1	PA1	—
IN2	PA2	Shared with USART2_TX
IN3	PA3	Shared with USART2_RX
IN4	PA4	Shared with SPI1_NSS
IN5	PA5	Shared with SPI1_SCK
IN6	PA6	Shared with SPI1_MISO
IN7	PA7	Shared with SPI1_MOSI
IN8	PB0	—
IN9	PB1	—
IN10	PC0	—
IN15	PA0_C	Direct ADC channel (H7 specific)
IN16	—	Internal temperature sensor
IN17	—	Internal VBAT/4
IN18	—	Internal VREFINT

USB OTG FS

Function	Pin	AF	Notes
DM	PA11	AF10	USB Data Minus
DP	PA12	AF10	USB Data Plus
ID	PA10	AF10	OTG ID (host/device detection)

Pin Conflict Quick Check

Before finalizing your pin assignments, watch for these common conflicts on the H743:

Conflict	Pins	Resolution
SPI1 MOSI vs ADC1_IN7	PA7	Use one or the other, not both simultaneously
USART1 TX vs I2C1 SCL	PB6	Pick alternate pin option for one peripheral
TIM1_CH2 vs USART1_TX	PA9	Cannot use both on PA9 — use PE11 for TIM1_CH2
USB DP vs TIM1_CH4	PA11/PA12	If using USB, route TIM1 to port E

When in doubt, open STM32CubeMX, select your chip, and enable your peripherals. CubeMX will highlight pin conflicts in red.

Embedded Systems Programming with STM32 and Rust