I thought of the termination resistors, especially when I found that if I have one channel not connected to the level shifter, it would pick up and respond to signals from a connected channel. I tried a 1K resistor on the 4th channel, one of 4 that have the most trouble, which cancelled responding to crosstalk when not connected to any input on the controller side, , but not the flashing and blinking when connected to the input.
There is a bit of ringing and overshoot at the start of a bit packet, but didn't seem too bad to cause trouble. But then I don't think I am able to see a problem bit or string of bits.
What's also interesting is the errors are getting past the first pixel. Usually the first pixel reconstructs the signal it receives when it passes it on to the next pixel
My plan and how I am testing is to power the controller from the display, the display getting the main power.
The test board is powered from the other end of the board, at the 30th pixel of the 16x30 board.
However I have a spare 300 LED strip which I power from the input side, and it too experiences problems.
I realize the cable is not ideal, it is a straight bundle of 20 24ga wires, where I use 16 for the 16 data channels, 2 pairs to send power back from the display to the Pico/74HTC245.
There is a bit of ringing and overshoot at the start of a bit packet, but didn't seem too bad to cause trouble. But then I don't think I am able to see a problem bit or string of bits.
What's also interesting is the errors are getting past the first pixel. Usually the first pixel reconstructs the signal it receives when it passes it on to the next pixel
My plan and how I am testing is to power the controller from the display, the display getting the main power.
The test board is powered from the other end of the board, at the 30th pixel of the 16x30 board.
However I have a spare 300 LED strip which I power from the input side, and it too experiences problems.
I realize the cable is not ideal, it is a straight bundle of 20 24ga wires, where I use 16 for the 16 data channels, 2 pairs to send power back from the display to the Pico/74HTC245.
Statistics: Posted by DanMan32 — Fri Feb 02, 2024 1:36 am