Part Number:TLC5929
Hi,
all signals, including SCLK, SIN, LAT, BLANK are affected by shift_speed / gray_scale_speed change. Basically, when you change from 3 to 2, all signals become faster (on and off times for each signal are shorter) and when you change from 2 to 3, all signals become slower( on and off times for each signal are longer).
In any case, customer having problems even with speed set to 3.
One thing that I discovered last night when testing with revision B board is that it works ok, immediately after the board is powered on. I don't see any ghosting problems and all test patterns look ok, but as soon as I write "function control data", it starts showing ghosting. This happens even if I write the exact same value to "function control data" as it was after power-up, which is E67Fh. To make it clear here are steps that I do:
1. Power off LED module and power it on -----> Everything looks ok, no ghosting
2. Move horizontal line up and down -----> Everything looks ok, no ghosting
3. Send E6F7h to function control data ------> Ghosting starts
I will double-check my FPGA code over next few days to make sure there are no mistakes there, but it seems as soon as I write any function control data, LED driver outputs start to leak some current and that causes ghosting. Here are my questions:
1. Do I need to have all data latches to 0, before I make changes to function control data?
2. Do I need to set BLANK to hight, before I make changes to function control data?
3. Is it possible that default value after power-up for function control data latch is not E67Fh, but some other value?
4. Is there any other way to reset LED driver to the default value, other than power-up reset?