Hi, I am working on pressure regulation project with an Arduino Leonardo. The idea is to have a tank maintained at a constant pressure (small vacuum in this case ~-20 mbar). To achieve this, the tank is connected to a pressure source and a vacuum source. Both sources are controlled by proportional valves. These valves are controlled with PWM signals. Moreover, the vacuum inside the tank is measured with a vacuum sensor that communicates by I2C with the Arduino.
To avoid noises, I set the timer 4 manually so it can provide a PWM signal at ~15kHz. Using registers OCR4A and OCR4D I can control both valves with the pins 5 and 6. I also use a PID from the livrary PID_v1.
The idea now is to have an interrupt every every 10ms (generated with the timer 0) during which I read the latest sensor value and then I compute the valves’ command with the PID library.
Unfortunately, I am encountering issues with my PWM that gets stuck with a 0% duty cycle when I execute both tasks : sensor reading + PID computing. In the actual configuration, I don’t even process the PID’s output value, so the PWM’s duty cycle should not vary.
I have tried to put some time margin between sensor reading and PID computation and also to lower the frequency down to 1Hz but I still have the same issue…
Please find my main sketch below.
Would you have any advice for me? What could cause this PWM interruption?
Best regards,
Loic
MeniscusPressureRegulator.ino (6.77 KB)
