I am intending to use 3 Teensy's on my next project to drive a

I am intending to use 3 Teensy’s on my next project to drive a 720x24 matrix using the Octo mode. Obviously I need to sync them and was wondering if the FastLED Octo code implements the sync line on the Octo adapter board?
I would also like to know if the PWM DMA data conversion from the FastLED led array always takes the same time irrespective of the led values? I can synchronize the calls to show() but have no control over the initial bit slicing phase of the call.

it’s not exactly the same, and even if the code was exactly the same, because it is interruptible the total time for it to run is non-deterministic.

That said, the difference is likely to be small enough that as long as you synchronize your calls to show (an exercise left to the reader, in this case, you :slight_smile: you should be fine.

I appreciate the point about interrupts, does your implementation have the Sync line feature on pin 12? Can’t find out much about it, presume it syncs up the PWM’s.
I have a couple of Octo boards and a 64x16 matrix so will do some testing. I am intending to run the same code on all boards using 2 digital lines to control shifting each boards display window and identify the master board for syncing.

I honestly have no idea how octows2811 uses the sync line, so I’m not sure if it will be used here.

It seems that the Octo sync line is controlled by a single master board and is implemented in their teensy code that receives usb data from a host pc.
I have implemented a simple Sync class that uses 2 digital lines, one is a digital output that indicates the board is ready to show() leds and a second digital input that all boards wait on before calling show(). On the hardware side you need to connect the 2 pins together with a resistor and then link all the input pins together.
The class also implements a board numbering scheme using up to 5 digital pins as a hardwired binary number giving board numbers from 0-31.
If anyone indicates an interest in the class I can post it on my github :slight_smile: