Using RPI3B+. I need to have 2 pins (a clock and data) to write data to shift registers on frequencies of 1,76 MHz or rate of 1,76 Mbps, and 1 pin(connected to GPIO 18) on 20 kHz.
Tested RPi.GPIO.PWM on normal gpio pins but the response was this: Input frequency of 1000 Hz gave me about 850 Hz. 6000 Hz about 3200 Hz. It maxed out at a very unstable 6-7Khz with any extremely high number as input. So the purpose of that library is probably for lower frequencies.
[Question: Are other GPIO libraries better for creating PWM pins or writing data at these rates?]
[Edit]: I already use SPI0 for a LCD. I have 11 74hc595 shift registers daisy chained and want to have PWM output on their outputs on at least 20 kHz instead of just high and low. So I thought:
-Latch needs to be at least 20kHz.
-Clock and data synchronous on at least 8*(11 shift registers) * Latch speed = 1,76 MHz\ Mbps.