I got in my setup a RPi Zero 2W and it is supposed to feed two displays (GC9A01) through SPI. I've connected each display in a different bus: the left display is connected to spidev0.0, whereas the right one is connected to spidev1.0.
The problem that I'm facing is that the bus 1 is much slower than the 0. With the same frequency (190 MHz), I'm uploading a frame (96 KB) in 13-14 ms in the left display. The right one is behaving weirdly: as soon as I start my upload script, it'll take like 32 ms to send a frame. After something like 5 seconds of uninterrupted uploading, this time will increase to 43 ms. The timings stay stable for the left display.
For uploading, I've used both a Python library (spidev) and a Rust one (rppal), and the results were consistent. So, if it is a software issue I assume it is some system-wide configuration. It's worth noting that the 190 MHz of frequency is the highest value I could find didn't bug the right display (increasing further would cause the image to look darkened). The left bus could definitely handle much higher frequencies.
I have confirmed that the same happens in a different PI with different displays. I wanted to know if any of you have faced something like that before, and got any ideas on why this is happening. Is the second bus slower by design?
The problem that I'm facing is that the bus 1 is much slower than the 0. With the same frequency (190 MHz), I'm uploading a frame (96 KB) in 13-14 ms in the left display. The right one is behaving weirdly: as soon as I start my upload script, it'll take like 32 ms to send a frame. After something like 5 seconds of uninterrupted uploading, this time will increase to 43 ms. The timings stay stable for the left display.
For uploading, I've used both a Python library (spidev) and a Rust one (rppal), and the results were consistent. So, if it is a software issue I assume it is some system-wide configuration. It's worth noting that the 190 MHz of frequency is the highest value I could find didn't bug the right display (increasing further would cause the image to look darkened). The left bus could definitely handle much higher frequencies.
I have confirmed that the same happens in a different PI with different displays. I wanted to know if any of you have faced something like that before, and got any ideas on why this is happening. Is the second bus slower by design?
Statistics: Posted by bernardolansing — Wed Aug 07, 2024 3:23 pm — Replies 0 — Views 2