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Figure 8 - The inside edges of the circuit board have just enough clearance
Figure 8 - The inside edges of the circuit board have just enough clearance

Once inserted, the keypad circuit board has just enough room between the box lid edges and the edges of the board as shown in Figure 8. This is why an enclosure with an inside diameter slightly larger than the edges of the keypad circuit board was necessary. An external mounting of the keypad would not be so critical.



Figure 9 - Soldering the keypad matrix wires to the circuit board
Figure 9 - Soldering the keypad matrix wires to the circuit board

You will need to solder a wire for each row and column needed on your keypad as shown in Figure 9. Having four rows and three columns, my keypad needed seven wires in total. If your keypad has digits you don't plan to use, it may be possible to leave an entire row or column unconnected, but you will need to look at the datasheet to see how many digits you will lose by leaving a row or column unconnected. If I dropped row four from my panel, I would lose keys "*", "0", and "#" according to the matrix mapping shown in Figure 2. I didn't care about the symbol characters, but wanted to use the zero, so I had to connect all of the rows and columns.

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