Ports and Pins by Function

This page gives an overview and description of the many connections on the STorM32 main boards. For the details of their function and usage please consult the other wiki pages.

The info on this page refers to the v3.1 and v1.3 STorM32 boards. For v1.1 and v1.2 boards small but important differences exist; read carefully the comments below. The pins of the v1.31 board are identical to that of the v1.3 board. The location of the ports are provided in Pins and Connectors.

Except of the ports POT and BUT all ports are 5 V tolerant, which means that you can apply signals with voltages of up to 5 V to their pins without damaging the board. The ports POT and BUT are however not 5 V tolerant. The voltage on the POT and BUT pins must not exceed 3.3 V.

The 3.3 V pins must only be used as supply. Never apply any voltage to a 3.3 V pin (unless you're an expert and know what you do).

Comment: The pin assignments below refer to the pin assignments on the STorM32 main boards; for NT modules they can be different, such as for the NT and NT-X bus ports.

MOT0, MOT1, MOT2

Function: These ports are the connectors for the motors (MOT0 = Pitch, MOT1 = Roll, MOT2 = Yaw by default).

NT Bus Port

Pins: Gnd, Rx, Tx, 5V

Function: Connector for the NT bus, where all NT modules go to.

Comment: The sequence of the Rx, Tx pins is swapped as compared to the NT bus port on the NT modules!

NT-X Bus Port

Pins: Gnd, Rx, Tx, 5V, Gnd, BAT, BAT

Function: Connector for the NT bus, where all NT modules go to, inclusive a pass through for the battery voltage.

Comment: The sequence of the Rx, Tx pins is swapped as compared to the NT bus port on the NT modules!

Comment: The NT-X port may be populated with a 6-pin connector instead of a 7-pin connector. If so, then the 2nd BAT pin is not present.

WARNING: Be very careful with that port, the BAT pins carry the battery voltage and any contact to any of the other pins will immediately destroy the STorM32 board.

I2C (NT Bus Port)

Pins: Gnd, Tx, Rx, 3.3V

Function: Connector for the NT bus, where all NT modules go to.

Comment: In I2C-based setups, the pins of this port are assigned to the I2C lines Gnd, SCL, SDA, and 3.3V. Hence the name of this port.

I2C#2

Pins: Gnd, SCL, SDA, 3.3V

Function: Connector for an external I2C-based 2nd MPU module, if this is to be used instead of the on-board MPU.

WARNING: On v1.1 boards the pins of connector I2C#2 are in reverse order to those of connector I2C, which implies also reversed voltage polarity. Pay attention to that before connecting a second IMU to the I2C#2 port.

RC

Pins: Gnd, RC-0, RC-1, RC-2

Function: The pins on this port can serve multiple functions, depending on parameter settings.

Their default function is to provide inputs for RC PWM signals. Typically RC receivers are connected to here. The input pulse lengths of 1 ms to 2 ms are converted to the value range -500 ... 500. The frequency of the input pulses can vary, and can be as high as 430 Hz.

Pin RC-0 can alternatively be configured as input to read the signal line from a Spektrum satellite, or the Futaba S-bus, and other serial protocols.

Pin RC-1 can alternatively be configured as output to generate PWM servo signals.

Pin RC-2 can alternatively be configured as input for sum PPM signals.

RC2

Pins: Gnd, RC2-0, RC2-1, RC2-2, RC2-3

Function: Inputs for RC PWM signals. Typically RC receivers are connected to here. The input pulse lengths of 1 ms to 2 ms are converted to the value range -500 ... 500. The frequency of the input pulses can vary, and can be as high as 430 Hz.

POT

Pins: Gnd, POT-0, POT-1, POT-2, 3.3V

Function: These three pins are connected to the analog digital converter (ADC) of the microprocessor and hence can digest analog signals. The analog signal is converted to the value range -500...500. Typically the central pins of potentiometers of e.g. a joystick are connected to here; the hot and cold potentiometer pins go then to the Gnd and 3.3V pins.

WARNING: Never apply signals with voltages larger than 3.3 V to any of these pins, this will destroy your board immediately!

BUT

Pins: Gnd, BUT-0

Function: This pin is actually also connected to the analog digital converter (ADC) of the microprocessor, but the analog signal are processed differently than those on the POT port. Currently this port is used to connect a key or switch to it.

WARNING: Never apply signals with voltages larger than 3.3 V to any of these pins, this will destroy your board immediately!

AUX

Pins: Gnd, AUX-0, AUX-1, AUX-2

Function: These are general purpose pins. Currently they are used to connect up to three keys and/or switches.

Comment: On v1.1 and v1.2 boards this port exhibits a 3.3 V pin instead of AUX-2, i.e. the pins are Gnd, AUX-0, AUX-1, 3.3V from right to left.

SPK

Pins: 3.3 V, Gnd, Signal

Function: Connector for a Spektrum satellite receiver.

Comment: On v1.1 boards the connector itself is not available, but the function can be accessed by connecting the Spektrum's signal line to the RC-0 pin.

IR

Pins: Gnd, IR-0

Function: Allows to connect an IR led to remote control a camera.

UART

Pins: Gnd, Rx, Tx

Function: Standard serial port to communicate with the board. The serial is set to 115200 bps by default, no parity bit, one stop bit. Details of the communication protocol can be found in the article Serial Communication.

ESP / UART2

Pins: Gnd, Rx2, Tx2, RST, GPIO0, 5 V

Function: Second serial port to communicate with the board. Typical use is to connect an ESP8266 Wifi module for communicating with the board, see Using a ESP8266 Wifi Module, or to use it as interface to communicate with a camera, see NT Camera.

CAN

Pins: Gnd, CAN-L, CAN-H, CAN 5 V

Function: Standard CAN port to communicate with the board. The bit rate is 1 Mbits/s. Details of the communication protocol can be found in the UAVCAN manual. The CAN 5 V pin is not a power supply, but "only" a sense line which is used by the CAN transceiver to detect the presence of a CAN bus and activate itself.

SWD

Pins: SWDIO, Gnd, SWCLK, 3.3V

Function: Connector for programming the microcontroller using a ST-Link/V2 programming tool.

Comment: The SWD port is located right above the AUX port on the board.

Comment: On v1.1 boards the labeling of the pins is incorrect. On some boards the issue has been resolved by a sticker.