Hello All,
I apologize if someone has previously addressed this issue, but so far I have not found it.
I have a pair of TLC5940's driven by an AVR32 UC3B1128 controller. I'm using two PWM outputs to drive the GSCLK and BLANK signals. I am able to successfully write brightness values to the drivers and get visual results.
My problem is that when I have latched data into the chip and it is just running idle on the two PWM inputs, I will occasionally see a low intensity channel jump up significantly in brightness and then immediately drop back down to a previous level. It is extremely intermittent and randomly appears on a handful of my 100 board test environment. I'm running at 16MHz so the fastest transition I can make is 62.5ns, which fulfills all of the hold-off and setup times in the datasheet for the 5940's. I have confirmed that I'm not clocking or latching in any new value, the only interaction at this point is the two PWM's for GSCLK and BLANK.
GSCLK is a PWM running at 16MHz, period of 8 cycles, duty cycle of 4 cycles (50%).
BLANK is a PWM running at 16MHz, period of 32768 cycles, duty cycle of 32767 cycles. (i.e. 8*4096)
I urgently seek a timely solution as I have lot of product to modify or re-program before next week.
Thanks in advance,
Jeremy