Connect to UART
Last updated
Last updated
Understand what UART does (if not check: UART)
Identified UART pins (if not check: Identify UART)
You need to find the GND (ground), TX (transmit) and RX(receive) pins to communicate with UART.
When you connect the UART-USB adapter with the UART interface on the board, you have to connect RX and TX together like this:
There are different ways to connect to identified test pads:
If you are lucky, you find header pins where you can connect jumper cables to it. This is the easiest way to connect your UART-to-TTL USB adapter to an UART interface.
If your device has holes in the pcb for the UART connection, you can attempt to put jumper cables through it and tilt them, so they have a solid contact point:
On your PC use the following command to communicate over UART (you may have to adjust the baud rate)
Change the 115200 with the baud rate of your device (how to identify: see below)
If you see readable data: You done it correctly!
If you see unreadable data then you probably have the wrong baud rate. Example
Quick win: Try to guess the baud rate, the most common ones are:
9600, 38400, 19200, 57600, 115200 (which is probably the most common of all)
Baudrate.py is a script, which tests automatically for different baud rates
You can also try to manually identify the correct baud rate using a logic analyzer
When hovering your capture with the mouse in the Saleae Logic Software you can see the the width is equal to 111.111kHZ which is very close to 115200, so we should choose this baud rate
Congrats! You found your first serial connection! Check out the UART chapter on how to use this to dump the firmware from the device.