Why not use thirteen TPIC6B95s as the column drivers and eight P-channel mosfets as the row drivers?
Sounds a good idea , and I have built a test panel, but only 7 x 5 LEDs. ( I only have enough LEDs for the project in this format ! I am going to leave a physical gap between each character display - later on I might move to 8x8 and do scrolling )
I want to get this one panel going to test in the sun.
I have 5 rows driven by mosfets, and 7 columns with 7 resistors to DRAIN1 to DRAIN7 of the TPIC6B595. ( DRAIN0 not used )
One problem is that I have migrated to the RFM22B wireless modules ( and RF22 library ) that uses SPI and the pin 2 interrupt.
I have been using Shiftout to run my 7 seg displays ( latching ), but I now have have 24 characters that I wish to update , and it sounds like SPI is the way to go speed wise to multiplex each row sequencially ? Crossroads uses SPI for everything ( sorry this is new ground for me )
I have used SPI and each driven chip needs a chip select input ? So if I need 24 chip selects I could do that with 3 CD4017s and one clock pin of the arduino ?
My old Shiftout version just pumps out the data to the first data in pin.
If the receiver detects an interrupt ( I am hoping it is only when a message arrives ) it will presumably disrupt the display refresh?
I could possibly blank the display with the notG while it is dealing with the incoming data..
I am also trying to get my head round the array to store the data in. It used to be a binary byte for the 7 seg , which I just called up for shifting out the data for each digit.
Now I must send out the right byte pattern for the top row of the number for each digit, latch it in, then load the second row, and so on ?
I have searched for a library to do this, but they seem to be devoted to particular chips ( which are expensive here )
I am going to write a sketch to run this one display to show a couple of letters, using shiftout for now, if anyone has some pointers I will appreciate it .