LED Matrix

We have 8 LT1441M display modules that have been donated by Michael Erskine. 'RepRap' Matt started working on getting Arduino talking to the displays.

Datasheet

Git Hub Repo

Talking to the Displays

The displays uses shift registers in order to control the LEDs. There are 256 LEDs per panel, that's 2048 in total. Data is shifted out over the GSI and RSI pins in time with the CLOCK. After clocking out all 2048 pixels, LATCH the data.

Below is an modifed version of the Arduino shiftOut that out puts data on both GSI and RSI pins for the same clock cycle.

void shiftOutDual(int dataPin, int dataPin1, int clockPin, int bitOrder, int val, int val1){

	int i;

	for (i = 0; i < 8; i++)  {
		if (bitOrder == LSBFIRST) {
			digitalWrite(dataPin, !!(val & (1 << i)));
			digitalWrite(dataPin1, !!(val1 & (1 << i)));
		}else{
			digitalWrite(dataPin, !!(val & (1 << (7 - i))));
			digitalWrite(dataPin1, !!(val1 & (1 << (7 - i))));
                }

		digitalWrite(clockPin, HIGH);
		digitalWrite(clockPin, LOW);

	}

}

Connectors

Power: JST VH connector: http://www.jst.co.uk/productSeries.php?pid=133

Pin No.	Name	Function
1	V1	Power supply for LED (red)
2	GND1	Ground for IC
3	VDD	Power supply for IC
4	GND2	Ground for LED
5	V2	Power supply for LED (yellow-green)

Data: JST XH connector: http://www.jst.co.uk/productSeries.php?pid=136

Pin No.	Name	Function
1	GSI	Serial data yellow-green
2	/GAEO	Output enable for yellow-green
3	LATCH	Latch contents of shift register
4	GND1	Ground of IC
5	CLOCK	Clock Signal for data (read on L->H)
6	/RAEO	Output enable for red
7	RSI	Serial data red