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Design document describing the LED PCF8575 connections, and the Java implementation that drives the clock LEDs.
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Note: there are two PCF8575 IC used in this design. This IC is used as it can provide the current flow to
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directly control the LED. Alternative IC like the MCP23017 with less current capability would require a NPN
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# Parts
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## AITIAO PCF8575 16 IO Expander
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Since there are 20 LEDs, two ICs are required. In my case these parts I purchased do not match their documentation. My chip has solder bridges for all three address bits, A0 A1 A2. Also their description of a solder bridge across VCC-VDD appears to be backwards. I think as cautionary tale, I soldered the ICs down and lost access to their VCC-VDD bridge and couldn’t experiment.
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This companies chip functions correctly with the Chip VCC and LED anode voltage equal.
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## LEDs
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Cheapos.
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## Prototype board
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Half Size BreadBoard. You can see in the chart ‘Overall LED Connections’ I cut paths on the planar so the LEDs
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could be placed close to each other. You can buy larger BreadBoards from ElectroCookie, called snappable.
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On these boards each row, ie: A B C … has three solder lands and each letters trace are not connected to the
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