mark4:
I think I’ll try to follow Sparkfun’s “Using an Arduino to program an AVR” tutorial at http://www.sparkfun.com/tutorials/200.I don’t have the LED matrix backpack in front of me. It may be tight to solder on the ISP headers, but I think I can manage it.
Thank you so much, I’m very grateful for your help!
I followed that tutorial and it worked fine, even with an Uno.
To get the headers on I separated the LED from the backpack and soldered it from the back.
Question - there are lots of errors in the backpack documentation.
-
The input and output SPI headers are backwards as you know.
-
The red and green LED codes are backwards. Red = 2, Green = 1.
-
The pixel positions do not follow the documentation, either.
-
The code they supply is for an earlier revision with some board errors and will not work unmodified on current boards.
Do you want me to fix number 2 or number 3? Not much I can do with number 1.
Number 2 - trivial or I can leave alone for compatibility.
Number 3 - I would need to know where you want pixel 1 and the order.
I have also optimized the code so that the SPI can run faster. I have the code instrumented with some pin level changes on writing to the transmit SPI buffer. I will see how fast it’ll go by looking at the pin outputs on a scope.
Initial tests look good with SPI_CLOCK_DIV8 (2 MHz), no delays on chip select going active, and only 5 us on chip select going inactive.
Jim