I'm using 10 pieces of the TLC5940 in a daisy chain configuration, here is my schematic:
In rare cases it happens that one ore more of the LEDs are wrongly set.
For further investigation I created an firmware, where all LEDs are controlled with the same brightness directly after power on. So if I toggle my power supply very often, I see sometimes LEDs with different brightnesses. Usually this happens in 1 out of 50 trials, but sometimes more often.
I suppose, this behavior could have to do something with the Dot Correction. I can't write Dot Correction Data directly as I don't have the I/O pins for DCPRG and VPRG in my target application (the above schematic is only a subset). But the datasheet is describing the alternative method with only one sentence:
The other solution is to overflow the input shift register with 193 bits of dummy data and latch
it while TLS540 is in GS PWM mode.
My question is, how to perform this in my Daisy Chain configuration? Normally I would shift out 192 bit x 10 = 1920 bit of Grayscale PWM values. Do I need to shift out 1930 bit or 1921 bit?
One more text in the datasheet confuses me:
The first GS data input cycle after dot correction requires an additional SCLK pulse after the XLAT signal to
complete the grayscale update cycle.
Are both sentences related to each other? And again, how this has to be done in my Daisy Chain configuration - how many bits in total?
Any ideas?
Thanks in advance!
