Hello,
I am trying to operate a TLC5946 to no avail. I am driving it with a microcontroller connected to the tlc by a ~30" 6 conductor ribbon cable. I have used an oscilliscope to check the signal quality at the microcontroller and at the TLC5946, and the signals all appear to be uncorrupted. I've used a multimeter to check for shorts and low resistances, and found all resistances between pins to be in the megaohm range. The software I'm using to control the TLC5946 is ported from functional software I wrote to control the TLC5940, the only difference being the way dot correction must be configured (different lines). Instead of working, I'm seeing this behavior:
The device will not turn on any outputs unless it is recieving regular blank pulses at some interval; however, this interval does not appear to affect the brightness of the outputs. For instance, I could toggle the blank every 20,000 GS clocks, and it would be the same subjective brightness as if I toggleed it 256 GS clocks. The device must be in GS mode, but it doesn't seem to care whether I load it with DC data--even if no DC data is sent, it behaves the same. The serial clock line doesn't appear to matter insofar as activity on it doesn't affect the device, but each pulse on the serial data line causes the TLC5496 to advance through a 113 state progression, and then have all outputs off. The progression looks like:
0000000000
11111111111
22222222222
Where those are the 3 different outputs, partially overlapping in their on times. The appear to ramp up and then down. Note that this progression is triggered by pulsing the serial data line (the clock remains held to ground). This also requires a pulse on XLAT before the pulsing of the serial data line begins.
If you have any ideas about 1) what could be causing this 2) additional triage I can do, I'd really appreciate it.
Thanks,
David
