Continuing the discussion from Purpose of 'Acknowledge' Command:
After a bit more finagling, I was able to get my LED to turn off before taking OD and then turn back on after. Success!
In a similar way, I want to turn off pumps that I’ll be using to bubble air into the culture.
I’m assuming that I need to minimize lag time with the whole on/off routine, so I need to control these pumps using the same Arduino that does OD and light. Otherwise I would have these pumps on the fluidics module and have a communication with the system there.
I’d be controlling the pumps (which run off of wall AC) via a relay, so that the 12V eVOLVER architecture could turn them on and off.
Therefore I see two options:
Plug the relay/pumps into the circuit that’s controlling the light.
- So the PWM for the light pin on each vial would run 1) an LED and 2) a relay that powers a pump
- I tried this in parallel to minimize voltage drop in the LED and it worked
- BUT it burnt out my relay because when the LED turns back on the voltage spikes to 16
- Another problem is that I want to be able to run the LED at anywhere between 6V and 12V to produce a variety of different light intensities. So a potential relay would need to be able to 1) withstand 16V spikes 2) turn on between 6 and 12V… This seems unlikely to be thing on its own
- Therefore I’m thinking that I could use a voltage regulator to keep the voltage at constant 6 volts regardless of input
- However, any changes in the relay circuit would affect the LED? Not sure about this…
The simpler option? Run the relay off of one of the pins on the arduino
- The Arduino can output a constant voltage
- Don’t have to have 16 relays
- No affecting LED values
- No delay
My question: are any of the pins on the Arduinos not being used by the two sub-boards? I can’t seem to find current layout of the motherboard on the github
I would also love general design feedback on solving this problem because I’m really just starting to learn electronics.
Thanks in advance for any help!