Question 8.20: You want to know how to use a Pi Plate prototyping board....

The Pi Plate (Figure 8-16) is a prototyping board rather than an interface board like the PiFace (Recipe 8.16) or RaspiRobot board (Recipe 10.8). In other words, it does not include any electronics—it is designed for you to solder your own components to a prototyping area.

Unlike the Humble Pi (Recipe 8.19), the Pi Plate does not have cutouts to work around the taller sockets on the Raspberry Pi; it is rectangular and exactly the same size as the Pi itself. It achieves this by using an extra tall header socket that lifts the whole board high enough to clear all the components on the Raspberry Pi.

The board also has an area where a 16-pin, surface-mount chip can be used and a row of four holes, spaced more widely, where a screw terminal can be soldered in place.

The board has screw terminals on two sides that are connected to all the GPIO pins. You can ignore the prototyping area entirely and just use the screw terminals to attach things directly to the GPIO pins without soldering.

Discussion

The board design has a grid of holes at a pitch of the standard 0.1 inch used by most through-hole components, including DIL ICs. You solder components to the board by pushing the leads through the holes at the top and soldering the connections underneath.

The tracks that connect the holes are clearly visible on the top of the board, and the board is divided into several zones. There is an area with central power busses intended for DIL ICs as well as a general prototyping area and areas for a surface-mount chip and extra screw terminals.

Having soldered the components into place, you will need extra wires to link everything up. These can be run on the bottom of the board or the top, or both if the design is complicated.

It’s a good idea to plan out the layout before you start soldering.

In the following instructions, you will build an RGB LED onto a Pi Plate using the layout shown in Figure 8-17. This recipe is a version of Recipe 9.9, which is the same except that the design is built onto a solderless breadboard.

The first step is to solder the resistors into place. Bend the leads and push them through the appropriate holes in the board. Then, flip the board over and touch the soldering iron to where the leads emerge from the hole for a second or so before applying the solder, which should flow around the lead (Figure 8-18).

When you have soldered both ends, snip off the excess lead and repeat for the other two resistors (Figure 8-19).

Now solder the LED into place, taking care to get it the right way around. The longest lead is the common cathode and should be the only LED lead attached to the strip of holes that is not connected to any resistor. Very occasionally, you will find LEDs where the longer lead is not the positive lead. This is often the case with infrared LEDs. So, if you aren’t sure, check the datasheet for the LED or the supplier’s information page.

You will also need to solder a short length of wire from that row to the GND connection on the Humble Pi (Figure 8-20).

When the board is complete, it should look like Figure 8-21.

You can try out the LED using the Python program from Recipe 9.9.

See Also

There is more information about this product at the Adafruit website.

The Pi Plate from Adafruit is a similar design to the Humble Pi (Recipe 8.20). The example in that recipe will give you an idea of how to solder components onto the Humble Pi.