Serial Ports

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Revision as of 10:37, 4 August 2025 by OlliW (talk | contribs) (Created page with "This article provides clarification regarding the STorM32's serial ports. <div class="toclimit-2">__TOC__</div> == Ports == Generally, the STorM32 port naming follows this scheme: The name of a port is simply the type of the port, plus a number for a 2nd port of that type, and so on. Example: {{BOX|RC}} and {{BOX|RC2}}. The STorM32 serial ports are named {{BOX|USB}}, {{BOX|UART}}, {{BOX|UART2}}, and {{BOX|UART3}}, and are accessible in the GUI as {{PARAMVALUE|usb}}, {...")
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This article provides clarification regarding the STorM32's serial ports.

Ports

Generally, the STorM32 port naming follows this scheme: The name of a port is simply the type of the port, plus a number for a 2nd port of that type, and so on. Example: RC and RC2. The STorM32 serial ports are named USB, UART, UART2, and UART3, and are accessible in the GUI as Template:PARAMVALUE, Template:PARAMVALUE, Template:PARAMVALUE, and Template:PARAMVALUE. The pins corresponding to these serial ports are labelled as Rx/Tx.

There is one exception, found on the the v3.3 board: UART1. It is not a port like UART or UART2, and you won't find any parameter option Template:PARAMVALUE in the GUI.

Comment: The naming scheme may be confusing to those coming from the FPV-world, since in that world it has become common to name the UART ports by the MCU peripheral name. STorM32 doesn't follow that scheme (STorM32 is older than the FPV scheme in fact LOL), it rather follows the PX4/ArduPilot approach.

MCU Peripherals and Special Role of UART1

Few words on microcontroller (MCU) peripherals. STorM32 uses the STM32 series of chips. The STM32's serial peripherals are called UARTx or USARTx, where x goes from 1 to 5 for e.g. the STM32F103RC chip (we will not distinguish between UARTx or USARTx but just call them UARTx). Note: This naming convention is a choice of the chip manufacturer, not ours.

 The names for the MCU serial peripherals must not be confused with the names of the serial ports of the STorM32 controller! They may or may not coincide.

For the STM32F103 chips used by the v3.3 board, the hardware peripheral UART1 is special, since it allows us to flash firmware into the microcontroller, and this is exploited by STorM32. On the v3.3 boards, the pins for the hardware peripheral are exposed, and this is the reason for why one finds a UART1 port (or Rx1/Tx1 labels) on this board.

Availability

Concerning the availability of the serial ports (for STorM32 boards documented in this wik) one can note:

The v3.x, v4.x, v6.x STorM32 boards all provide the USB, UART, UATRT2, and UART3 ports.

The UART3 port is shared with two pins of the RC port, pins RC-0 and RC-1

Gui v3.3/v4.1 ! v6.2
Template:PARAMVALUE UART port
Template:PARAMVALUE UART2 port
Template:PARAMVALUE USB connector (is internally connected to UART1 for)
Template:PARAMVALUE RC-0,RC-1 pins on RC port
labeled UART3

Baudrate

The default baudrate is generally 115200 bps for all serial ports (including USB on the v3.3 and v4.1 boards).

They can be adjusted for the USB, UART, UART2 serial ports in the GUI. There is no possibility to adjust the baudrate of the UARTX serial port.

Comment: The GUI per default also communicates with a baudrate of 115200 bps. It can be changed in the GUI.

Comment: Changing the baudrate of a serial port can imply that one cannot connect to this port with the GUI anymore.