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The 3-to-8 decoder selects one particular row to light, through pins A/B/C. | The 3-to-8 decoder selects one particular row to light, through pins A/B/C. | ||
The MOSFETs are used as drivers. | |||
The SCLK signal goes to the CLK input of all serial-parallel SNHC164 chips. | The SCLK signal goes to the CLK input of all serial-parallel SNHC164 chips. | ||
Revision as of 21:56, 19 March 2022
This page is about a lichtkrant, bought by flok.
Hardware
It has of 16 blocks of 5x8 LEDs, for a total of 80x8 LEDs. It is unknown if it's monochrome (just red) or two-color (red + green).
The electronics consist of two parts: a controller board and a LED board.
The LED board has the following ICs:
- SN74HC138: 3-to-8 line decoder/multiplexer
- SN74HC04: 6 inverters
- 10x SN74HC164: 8-bit parallel-out serial shift registers
- 4x APM4953: dual P-Channel Enhancement Mode Mosfet
The boards are connected through a 10 pin connector. There is also a 5V connector.
Theory of operation
There are 80 pixels horizontally and 10 serial-parallel chips with 8 outputs each, so one row of pixels can be kept in the shift registers.
The 3-to-8 decoder selects one particular row to light, through pins A/B/C. The MOSFETs are used as drivers.
The SCLK signal goes to the CLK input of all serial-parallel SNHC164 chips.
Connector
Pinout:
- pin 1: SCLK
- pin 2: SCLK (shorted to pin 1)
- pin 3: G
- pin 4: R
- pin 5: A
- pin 6: B
- pin 7: C
- pin 8: D
- pin 9: GND
- pin 10: GND