My Raspberry Pi 4 + JTAG setup — Part 2 — The Hardware Setup

First, we’ll walk through the HW setup. More specifically, the portion of the diagram below that connects the two green boxes and the USB connection from the Host System to the FT232. This is a fairly simple setup. The HW consists of the Raspberry Pi 4, a FT232H breakout board, 6 jumper wires and a USB-C cable.

** WARNING **: There should be no power connected to the Raspberry Pi 4 and NO USB connected to the FT232 board while hooking up the Jumper wires. Hook these up first. This will be safer for you and the HW. There are no high voltages here, but doing this with the power off is always a good idea.

Probably the most complicated part of this is soldering the pin headers onto the FT232 board. However, I will not cover the soldering of the pin headers.

The headers can be oriented toward either side of the board. The picture below is my setup. I put the headers ‘under side’ of the board and mounted the board in a ‘dead roach’ configuration (on its back with the pins/legs up). Installing the FT232 board on a breadboard is another option you might consider. In this photo, the raspberry pi is mounted on an oak plank and the FT232 board is held in place with standoffs.

The HW setup is simply connecting the 6 jumper wires from the FT232 Breakout board to the Raspberry Pi 4. From the Table below we are hooking up the following

  • D0 to Pin 22 RPI4 J8
  • D1 to Pin 37 RPI4 J8
  • D2 to Pin 18 RPI4 J8
  • D3 to Pin 13 RPI4 J8
  • C0 to Pin 15 RPI4 J8
  • GND to Pin 39 RPI4 J8

Once again, you should do this before connecting power or a USB cable.

AdaFruit Board
PIN Name
FT232H
Pin Name
JTAG FunctionRPI 4 GPIORPI 4 J8 Pin
D0ADBUS0TCKGPIO 25Pin 22
D1ADBUS1TDIGPIO 26 Pin 37
D2ADBUS2TD0GPIO 24Pin 18
D3ADBUS3TMSGPIO 27Pin 13
D4ADBUS4GPIONot Connected
D5ADBUS5GPIONot Connected
D6ADBUS6GPIONot Connected
D7ADBUS7GPIONot Connected
C0ACBUS0/TRSTGPIO 22Pin 15
C1ACBUS1/SRSTNo Connected
C2ACBUS2GPIONot Connected
C3ACBUS3GPIONot Connected
C4ACBUS4GPIONot Connected
C5ACBUS5GPIONot Connected
C6ACBUS6GPIONot Connected
C7ACBUS7GPIONot Connected
C8ACBUS8func definedNot Connected
C9ACBUS9func definedNot Connected
GNDGNDGNDGNDPin 39
JTAG – Raspberry Pi Connection Details

Once these 6 wires are connected, you can connect USB-C cable between the FT232 and your PC. The AdaFruit FT232 board has two sockets on it, the image blow is of the USB-C connector.

Although the FT232 uses a USB-C connector, this is just a regular USB connection and you can use a USB-C to USB-C or USB-C to USB-A cable. Connecting the cable to your computer should be something you are already comfortable with.

Here is another image of my setup with the USB attached.

For information about connecting power to the Raspberry Pi 4, please consult the documentation that came with your Raspberry Pi 4.

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