Im working on a design very similar to Matt Pandina, except I want to attempt it on something other then a customized Atmega328p.
The current usage is to send data via SPI to the TLC5940's while they are displaying the previous data, then read from an SDcard the data for the next run. This requires very tight timings, atm Matt goes thru all three phases RGB in around 500uS, which is one scan line. 166uS per color, and sending 96 bytes per color, 3 colors in all.
166.667uS = 6000Hz
24bytes x 4 TLC = 96 Bytes
6000 x 96 = 576000 bytes/s or 4608000 bits/s this would be the absolute minimum for this refresh rate, you would want at-least another 15% leeway
The Teensy 3.0 has DMA SPI, does this mean you can read from an SDcard while you bitbang out to the TLC's on a different set of pins? How fast could you do it?
Since the Teensy 3.0 has more memory you could possible stay several lines ahead of the TLC's?
I have 3 prototype PCB's built so I can run tests, atm I have been working out more details on the Mosfets for sourcing the leds.
TLC5940 Datasheet
The current usage is to send data via SPI to the TLC5940's while they are displaying the previous data, then read from an SDcard the data for the next run. This requires very tight timings, atm Matt goes thru all three phases RGB in around 500uS, which is one scan line. 166uS per color, and sending 96 bytes per color, 3 colors in all.
166.667uS = 6000Hz
24bytes x 4 TLC = 96 Bytes
6000 x 96 = 576000 bytes/s or 4608000 bits/s this would be the absolute minimum for this refresh rate, you would want at-least another 15% leeway
The Teensy 3.0 has DMA SPI, does this mean you can read from an SDcard while you bitbang out to the TLC's on a different set of pins? How fast could you do it?
Since the Teensy 3.0 has more memory you could possible stay several lines ahead of the TLC's?
I have 3 prototype PCB's built so I can run tests, atm I have been working out more details on the Mosfets for sourcing the leds.
TLC5940 Datasheet
Last edited: