Monday, January 03, 2011

Christmas project - update

Two things took longer than I expected. The biggest job was definitely soldering the 480 LEDs and that is still half done.

Making and soldering the controller board also took longer than I expected. Part of this was transferring the design to stripboard - I'd 'paper designed' the chip and transistor pin connections but there were placement and wiring issues.

Three placement/wiring issues worth noting were: 1. between the microprocessor board and logic gates (3-8 line converters), 2. transistor placement/spacing and 3. microprocessor board connector (where I had to create a connector).

On the controller board, so far, there are five ports giving problems. Two are related to the ports (P0.2/P0.3) being for I2C (as well as other functions) and therefore don't have active pull up to high (open-drain/open-collector type ports). Just requires some resistor pull-ups.

Another port works but the transistor output is not toggling. It's obviously a board or transistor problem and should be simple enough to fix.

Another port is not toggling even when the controller board is disconnected - even the micro pin is not toggling.

Finally there is one port which is toggling but the logic probe seems to show it 'rattling' when it's high. This will also need investigating.

There are a few other things to do after the LED soldering and port fixing, like making sure the LED matrix wires are separated, completing the box construction, fixing the black facia board on, finishing the controller board hardware debugging and adding pictures to display.


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