Currently trying to build a very large and very fast persistence of vision display and have run into the issue of achieving the desired refresh rates on 4 LED strips concurrently, while sharing a clock line. As a relative beginner, I've certainly bit off more than I can chew with this project but hopefully you guys will be able to provide some guidance.
The SK9822 is controlled by sending a series of bytes over a simplified SPI interface with data(MOSI) and clock wires. My current plan is to take all 4 bytes, one for each strip, and combine them into a uint32_t such that 00000000, 00000000, 00000000, and 11111111 become 000100010001.... Then, send that combined uint32_t at a high frequency into a shift register via SPI. Using 2 D-type flip-flop clock dividers, It seems like I could latch the shift register after 4 bits and then use the inverse of that to create a clock line, in essence creating 4 SPI MOSIs at 1/4 frequency.
Essentially, my novice mind thinks this would work to drive the LEDs but I'm not really sure, but I think the best way to test this is to have a PCB made because I doubt it would work on a breadboard, but obviously I don't want to do that if it's not gonna work. So, do you guys think this is the right approach? Would it work as described? I've attached a diagram of the circuit I'm describing.
I'm not sure if I understand the question. I need to refresh 472 LEDs at a rate of 3280 r/s which is beyond the transmission capabilities of the sk9822 in series, so I'm not sure there is much of an easy way.
No experience with this strip, but I think the easy way is to enable/switch the clock (or data) line to one strip at the time. With two lines of the processor to a one in four switcher.
Which MCU are you using. There are boards with more than one SPI port.
Leo..
It's a Teensy 4.0, has 3 SPI ports but that won't work since they need to share a clock, or at least split 2 clocks (I'm running the wires through a slip ring for the POV display, and there are only 2 available wires for the clocks) The trouble is that the data rate I need to output is 52 MHz between all 4 strips, which is beyond what the SK9822 can handle (even straight out of the microcontroller it goes haywire above 30).
Paul on the teensy forum referred me to some Teensy-specific solutions involving the guts of the microcontroller, but after some exploration it seems that is quite far out of my wheelhouse with this only being my fourth Arduino project and first time messing with the teensy board.
Hopefully I'm allowed to post on here if I'm not using an official Arduino board...
