Orange Unit: A Person-Centered Launch
4D: Coding Electronics
Exercise: Connecting a Breadboard to a Raspberry Pi
In the previous two chapters of this Orange Unit session, 4B: Meet the Microcomputer and 4C: Getting Started with the Raspberry Pi, we began familiarizing ourselves with the application of computer building blocks specifically to the Raspberry Pi microcomputer. After meeting the hardware, we went on to set up a Raspberry Pi-based Linux operating system, an organic (that is, self-luminous) light-emitting diode (OLED), and a bootup script to display some essential current data on the functioning of the Raspberry Pi. The result looked something like this:
But in doing so, we’ve also reserved access to six of the General Purpose Input Output (GPIO) pins, including the only two 5-volt power pins.
Above, you can see two different displays of the pin layout formats commonly used with the Raspberry Pi GPIO[1].
Look through these and note that some, like #10, #9, and #11 just below the middle 3.3V pin, can be used for multiple purposes, such as digital inputs and outputs, or as a serial peripheral interface (SPI) connector with Master Out/Slave In, Master In/Slave Out, and Master Clock pins.
The use of the terms “master” and “slave” is rightly discomforting for many. As noted in the tween zine Beyond Dark Matter, “The master/slave relationship has been used for centuries in technology, often to explain situations where one master process or component controls a slave process or component” (p. 31, Beyond Dark Matter).
Efforts are made periodically to move away from this embedded framing of the master/slave relationship within core aspects of all our electronics. This blockquote seeks to unpack further the hidden sociopolitical and economic realities that remain encoded within our sociotechnical technologies and systems.
While there are many other pins for us to use than the ones covered by the PiOLED attached directly to the GPIO, this layout has proved less than optimal for later exercises, in which the Raspberry Pi is used with the breadboard electronics. This is particularly the case when a shared Raspberry Pi is connected and disconnected with different breadboards as each person tests out their own prototype[2].
For the next exercise, we’ll remove the PiOLED from the Raspberry Pi GPIO, and instead connect a 40-pin ribbon cable to the 2×20 GPIO of the Raspberry Pi. This can then be attached to a Cobbler or T-Cobbler on a full-sized breadboard. As we’ve used columns 1-30 for past exercises in the Orange Unit, we’ll now attach the T-Cobbler to columns 44-63 of the breadboard.
If your IP address changes moving forward, you may need to disconnect the ribbon cable from the GPIO pins of the Raspberry Pi and reconnect the PiOLED temporarily. Alternatively, you can reconnect the Raspberry Pi to a keyboard, mouse, and monitor.
Connecting the Raspberry Pi and Breadboard
While the Fritzing diagrams in the first half of the Orange Unit were illustrated