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UART Interface

UART or Universal Asynchronous Receiver-Transmitter is an asynchronous communication interface used mostly to transfer serial data between devices. It uses only two channels RX (receiver) and TX (transmitter) to send data, you don't need to connect any clock signal.

info

To read more about UART Interface usage with TOWER you can read the How To: UART Interface Chapter or the Debugging chapter.

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If you want to know more about UART there is an article about it.

TOWER has 3 UART channels, UART0 UART1 UART2, you can read where to find them in the Header Pinout chapter

UART Setup

As the UART channel does not have a clock signal that would synchronize the communication you have to set up both communicating devices so they are synchronized and know how to transmit and receive data.

There are three parameters that you can set up the UART with

  • Baud rate - this is the speed with which the data will be sent
  • Data Bits - number of data bits in each packet (5-9 bits)
  • Parity Bits - you can choose to have Odd, even or none parity
  • Stop Bits - this determines the end of one packet. It can be 1 or 2 bits
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You can see a short format of the UART setup configuration. For example, 8 Data Bits, No Parity and 1 Stop Bit can be represented as 8N1.

note

At the start of each packet, there is always one Start Bit.

If you set up both devices the same, you will get viable data, if not, you will receive not readable data.

Logging

A lot of devices use the UART to send the serial data from the device to the computer terminal. This is used to send log messages so the user/developer can read them.

TOWER uses UART2 for this, you can use twr_log_* SDK API to send the messages over this UART interface to your PC so you can debug while developing your application.

TOWER logging UART parameters

  • Baud Rate - 115200
  • 8 Data bits
  • No Parity
  • 1 Stop Bit
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You can visit a separate Debugging chapter**](/tower/firmware-development/firmware-debugging) to learn about how to do that.