SPI Backpack PCB for Liquid Crystal Displays: Part 3 Assemble and Test

The completed printed circuit board needs to be stuffed with components.

Populating a PC board is best done by placing the shortest components first and the tallest components last.

So first to go on are the Z wires. These connect traces on the bottom to traces on the top.  They are necessary because this homemade board does not have plated through holes.

Z wires

Z wires

The next higher parts are the resistors.

Adding resistors

Adding resistors

Next capacitors, chips, and the crystal.  Some of the leads have to be soldered on the top and on the bottom of the board.  Again, this is because I do not have plated through holes.

Add capacitors and chips

Add capacitors and chips

Now I attach the CAN connector, the contrast pot, and the header that mates with the LCD. These are the tallest parts

Add connectors, headers, and the contrast pot.

Add connectors, headers, and the contrast pot.

Finally, some rainbow wire to connect the backpack to the Arduino.  Also the backlight switch transistor at this time because it took a while to find one in my junk box.

Add wiring and the backlight switch transistor

Add wiring and the backlight switch transistor

Finally solder it onto an LCD display and see if it works.

It does!

Remote light level and temperature on the display

Head end prototype showing light level and temperature from the remote

Head end prototype showing light level and temperature from the remote

The project needs quite a bit of work on the software to be effective. The two SPI functions seem to interfere with each other.  Suspect a library conflic.

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    • Gordon Millar
    • May 23rd, 2012

    Excellent post! must take quite a bit of time to compose.
    Hope you noticed the fine short on the transistor middle pin : D

    • Yes I did catch that. It was due to a smudge on the laser printout.

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