dhempy / air-assist Goto Github PK

When the valve solenoid is present, garbage characters appear on the LCD display.
When the valve solenoid is not present, this problem does not occur.

Various changes to the relay, wiring and shielding attempts may influence the error, but never eliminate it.

We believe this is caused by back EMF:

The comments throughout this thread match our scenarios precisely:
https://forum.arduino.cc/index.php?topic=138322.0

Here's an article describing it and some fixes:
https://progeny.co.uk/back-emf-suppression/

FWIW, when we use an I2C display, this issue does not occur. It is only present with a parallel display. This may have also been the cause of the random resets seen in an earlier prototype, before we switched to a separate power supply for the solenoids. The more I think about this, I think this is extremely likely.

The display garbage should be considered merely as a symptom...the back EMF (if that is indeed the problem) has the potential to adversely affect anything in the system and needs to be eliminated.

"Standby or on/off function to stop flow during disconnection of ETT from vent without aerosolization"

Phase 1
Sound alarm.
Display message.
(Adjusting delivery settings upon alarm not included in Phase 1)

• Arduino generated:
  • Excess patient pressure 38 cm H20
  • Lack of pressure over 25 for 8 sec.
  • Lack of pressure below 20 for 8 sec.
  • Lack of suspend signal after 8 sec. (edited)

With different I2C backpacks we have seed that the I2C address can be different.

https://fritzing.org probably?

Read values - inhale and exhale
Display on LCD

Change next_appt use subtraction instead of addition to avoid long int overflow issue.

Possibly switch to jm_wire, or get away from I2C entirely.

Maybe Android tablet or RasPi w/touch screen.

Leave Arduino focused on essential, real-time operations. Maybe keep char display for simple stats output and buttons for basic param adjustment for redundancy. But primary graphing / param adjustment / logging occurs on computer.