Interfaces and Pinout

The V6 board uses two MCUs with the same pin assignment. Each MCU manages two CAN/CAN FD interfaces, two RS485 interfaces, one USB interface, and one external SPI slave interface.

Whole-Board Interface Mapping

Host entry point

Interfaces managed by the current MCU

Common board names

First MCU USB / SPI CS0

Local first and second channels

CAN1, CAN2, RS485-1, RS485-2

Second MCU USB / SPI CS1

Local first and second channels

CAN3, CAN4, RS485-3, RS485-4

USB and SPI commands may use whole-board Channel numbers:

  • Channel 1/3 selects the first interface on the current MCU.

  • Channel 2/4 selects the second interface on the current MCU.

  • Channel 0 selects both interfaces of the same type on the current MCU.

Replies use local numbering and therefore only report Channel 1 or Channel 2. For example, a reply from the first bus on the second MCU is marked Channel 1 even if the transmit command used Channel 3.

Pins on Each MCU

Function

MCU pins

Description

FDCAN1 RX / TX

PB8 / PB9

First local CAN/CAN FD

FDCAN2 RX / TX

PB12 / PB13

Second local CAN/CAN FD

RS485-A TX / RX / RE

PB6 / PB7 / PB5

USART1, first local RS485

RS485-B TX / RX / RE

PD5 / PD6 / PD3

USART2, second local RS485

External SPI CS / SCK / MISO / MOSI

PA15 / PC10 / PC11 / PC12

SPI3 slave for an external host

Internal SPI CS / SCK / MISO / MOSI

PA4 / PA5 / PA6 / PA7

SPI1 link between the two MCU devices

Debug UART TX / RX

PD8 / PD9

USART3

I2C SCL / SDA

PC6 / PC7

I2C4

ADC input 1 / 2

PB1 / PE9

ADC3

LED1 / LED2

PC4 / PC5

Active low

USB DM / DP

PA11 / PA12

USB composite device

SWDIO / SWCLK

PA13 / PA14

ST-LINK programming and debugging

These pins are used by the factory firmware. Before adding peripherals, make sure they do not conflict with CAN, RS485, USB, SPI, or the internal MCU link.

SocketCAN Interfaces

Each MCU exposes two gs_usb channels. A complete board normally appears as four Linux canX interfaces:

MCU

gs_usb channels

Physical interfaces

First MCU

0 / 1

CAN1 / CAN2

Second MCU

0 / 1

CAN3 / CAN4

Linux assigns can0, can1, and later names by enumeration order, so they may not match board silkscreen on every host. Confirm the mapping before production use as described in SocketCAN.

External SPI Settings

Item

Value

Role

Slave

SPI mode

Mode 0

Bit order

MSB First

Data width

8 bit

CRC-8 polynomial

0x07

SHORT

23 bytes including the final CRC byte

LONG

73 bytes including the final CRC byte

Factory default is SHORT. Switch to LONG only when SPI must carry CAN FD or more than 18 bytes of RS485 data.

Wiring Notes

  • Place suitable termination at both ends of a CAN/CAN FD bus and do not swap CAN_H and CAN_L.

  • RS485 A/B naming differs among manufacturers; if communication fails, check the transceiver labels.

  • USB, SPI hosts, and external devices should share a reference ground.

  • The two MCU devices have separate USB and SWD connectors; verify the selected side before updating or debugging.

  • Follow the schematic for your exact board version for connector and power definitions.