Lol (Lots of LEDs) Arduino Shield



... well the 9 by 14 LED matrix is an odd ball. Why the non 2² array? I was intrigued. (Memories from the 1980s with 132 by 25 character VDUs...)

Maplin's stock code: N97CE and 14.99 later.

Work in progress

The above is a photo from the font demo LoLShield_FontTest. It's scrolling, with the last letter of "Hello" and the first letter of "World".

There's some crosstalk... why??


I rework the interrupt routine in Charliplexing.cpp...

        PORTB = 0x0; // all low
	PORTD = 0x0;
	DDRD = 0xff; // all out
	DDRB = 0xff;

	if (page < (SHADES - 1))
		uint16_t pinMask = (4 << cycle);
		uint16_t charPattern = (*displayPointer);

		//charPattern = 0x0 & ~pinMask;

		uint16_t maskPattern = (pinMask | charPattern);

		PORTB = charPattern >> 8;
		PORTD = charPattern;

		DDRB = maskPattern >> 8;
		DDRD = maskPattern;


This helps me understand what's going on... but the crosstalk remains.

Useful Link

Atmel's Clever Pin Register


Watch this space!

Page last updated 14th March 2015

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