I just finished writing the software for the pressure profiling system and I'm now waiting for the hardware bits (stepper motor and elements to put together a power supply for it). To bore you a little bit and update this topic I thought I would explain how it's all going to work.
The PPS (pressure profiling system) will offer the following functions:
- full Manual mode in which the user can open/close the valve as much as he/her likes, adjusting the pressure within a range of 2-9bar. Control of the valve will be possible via a mom-off-mom toggle switch on the control box. Keeping the switch in the 'up' position will close the bypass valve thus increasing pressure and keeping the switch in the 'down' position will open the valve and decrease the pressure on the group. The 'pump on' signal won't affect the valve control in any way which means you can adjust the valve with the pump engaged or not.
- full Auto mode in which a predefined pressure profile is being executed when the 'extraction' button on the front of the machine is pressed. The system offers three custom set pressure profiles (see Programming mode) and one Default profile which is a 'preinfuse for 3s at 2bar - ramp up to 9bar in 3s - ramp down to 6bar within 21s'.
- Programming mode in which the user can set his/her own profile (via manual mode) and save it under one of the profile buttons (three buttons are available labled P1, P2 and P3). The buttons are the normal push-to-make momentary type and allow to both save (long press) and load (short press) previously configured profiles.
Switching between the Auto/Man mode is possible via an on-on toggle switch and Programming mode can be turned on/off via a mom-off-mom toggle switch to eliminate accidental activations. The control box also has 4 red LEDs to show which profile is active at the moment and 2 green LEDs for 'Pump On' and 'Programming On' indication.
Here's a drawing which shows how the faceplate of the control box will look like (it doesn't show the Programming ON LED):
Hopefully the whole thing should be working before the end of April.