ScarlettScroller

From NURDspace

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.

Only inverter 1 and 6 of the hex inverter is actually doing something.

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 = data bit shifted into row, goes through inverter 6
  • pin 4: R = ?, goes through inverter 1
  • pin 5: A = column select
  • pin 6: B = column select
  • pin 7: C = column select
  • pin 8: D
  • pin 9: GND
  • pin 10: GND