Preassembled 40-pin Pi Wedge Hookup Guide

Contributors: Byron J.

Assembly

Contents

The Preassembleed Pi Wedge comes with the Wedge PCB, and a 40-pin ribbon cable.

Connection

The 40-pin ribbon cable is used to connect the wedge to the Pi. This cable is polarized — notice that the pin 1 marking is very subtle. On the Pi Wedge PCB end, the tooth on the cable will interface with the notch in the shrouded header. Insert the IDC cable into the Pi Wedge's polarized connector so that the cable extends away from the breadboard connection.

Insert the Wedge into the center of the breadboard so that each pin has their own row.

The header on the Pi itself doesn't have anything to help guarantee the alignment. You'll need to take care that it gets connected properly. Pin 1 on the Pi is marked with a dog-eared corner on the silkscreened rectangle. The ribbon cable connector is embossed with (a barely visible) small triangle that marks pin 1. The first pin is also coded on the wire, such as the red markings in the photo below (though it may also be another color, such as black or dark blue). Insert the IDC cable to the Pi so that the cable extends away from the Pi.

Note: If you are using an enclosure (like the Pi 4 heat sink case, you may want to consider using an extension header to properly connect the Pi Wedge's IDC cable to the Raspberry Pi's GPIO pins.

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Extended GPIO Female Header - 2x20 Pin (13.5mm/9.80mm)

In stock PRT-16764

This 2x20 pin female header is meant to allow you to extend the reach of any board with the standard 2x20 GPIO pin footprint.

$2.25

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Extended GPIO Female Header - 2x20 Pin (16mm/7.30mm)

In stock PRT-16763

This 2x20 pin female header is meant to allow you to extend the reach of any board with the standard 2x20 GPIO pin footprint.

$2.25

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Extension headers are also useful when stacking HAT's with other single board computers that utilize the Pi's standard 2x20 GPIO header like the Google Coral and NVIDIA Jetson.

The extension header with 9.80mm pin length [ PRT-16764 ] is useful when sandwiching a PCB between a Pi and HAT. The header can also be used to sandwich a board betwen the Pi and Pi Wedge's IDC cable. The extension header with 7.30mm pin length [ PRT-16763 ] uses three plastic spacers which cover the pins more when using a HAT or the Pi Wedge's IDC cable.

Extension Header with 9.80mm Pin Length is Used to Help Stack the Qwiic SHIM and Pi Servo HAT on a Pi 4 with Heat Sink	Extension Header with 7.30mm Pin Length is Used to Help Connect the Pi Wedge's IDC Cable to the Pi 4 with Heat Sink

The height of the enclosure and PCB varies depending on the design. The image below shows a Pi 3 in the enclosure. The overall height of the enclosure is lower than the Pi 4's heat sink enclosure, so one 2x20 extension header was needed when stacking the Qwiic pHAT v2.0 on the Pi. You may need to stack additional extension headers so that the boards have enough clearance when using other enclosures and PCBs sandwiched between the Pi and IDC cable.

If you decide to connect to the Pi using serial, you can insert a 3.3V FTDI to the Pi Wedge. The FTDI connector needs to be aligned correctly. Be sure to match up the "GRN" and "BLK" markings on both boards.

Your setup will look similar to the image below. In this case, we used a Pi 3 in an enclosure.

In the next section, we'll explore how the signals from the Pi are mapped to the Wedge.