Reef-Pi Controllers: New all-in-one with power bar, and the original Pico

[dmolavi]

Got the power off working:

dtoverlay=gpio-shutdown,gpio_pin=19,active_low=0

I then have my momentary switch between 19 and 3.3v on a rail (provided by the 1wire connection).

It doesn't do power on, but that's ok.

WRT an LED - The 5V outputs on the Pico board are always hot, it looks, since power to the Pico is independent of the state of the Pi. This is actually good info - means that even if the Pi shuts down/reboots, stuff will stay on.

Are there any pins on the Pico that are tied to Pi power at all? I can go the USB route, but space is tight to get a connector in there

 

[theatrus]

Got the power off working:

dtoverlay=gpio-shutdown,gpio_pin=19,active_low=0

I then have my momentary switch between 19 and 3.3v on a rail (provided by the 1wire connection).

It doesn't do power on, but that's ok.

WRT an LED - The 5V outputs on the Pico board are always hot, it looks, since power to the Pico is independent of the state of the Pi. This is actually good info - means that even if the Pi shuts down/reboots, stuff will stay on.

Are there any pins on the Pico that are tied to Pi power at all? I can go the USB route, but space is tight to get a connector in there

Check the 3.3V line coming back from the Pi - it’s unused on the Pico board (outside of a capacitor).

 

[dmolavi]

Check the 3.3V line coming back from the Pi - it’s unused on the Pico board (outside of a capacitor).

I saw that on the schematics. Where is it exposed on the Pico?

 

[theatrus]

I saw that on the schematics. Where is it exposed on the Pico?

Unfortunately just the pin on the header and the adjacent 0603 capacitor. Any 3V3 stuff on the base board comes from a different regulator as the one on the Pi is fairly weak.

 

[dmolavi]

Unfortunately just the pin on the header and the adjacent 0603 capacitor. Any 3V3 stuff on the base board comes from a different regulator as the one on the Pi is fairly weak.

what's the 'safest' way to tap into this? (I'm at work now, don't have my board in front of me)...just solder a white-wire to the bottom of the board at either (physical) pin 1 or 17?

For < $1@, I'm gonna pick up a couple of USB connectors from Arrow, as well. I tried pulling apart an old cable last night, but the strain relief section was still too long for the clearance I have inside my enclosure.

 

[dmolavi]

@theatrus when you set the equipment to "on", does that send a constant 5 (or 3.3) V to the corresponding pins on the DB9? My pins read high at the console but I dont see any volts on the DB9 output

 

[Bigtrout]

If by equipment you mean outputs from a ULN2803, then no you would not see voltage.
The ULN2803 sinks current to ground. When its input is taken high, its corresponding output is then grounded which completes the circuit triggering the corresponding relay.

 

[dmolavi]

If by equipment you mean outputs from a ULN2803, then no you would not see voltage.
The ULN2803 sinks current to ground. When its input is taken high, its corresponding output is then grounded which completes the circuit triggering the corresponding relay.

Frack so the DB9 can't source current? Even if the GPIO pins are high? Or do I need to "reverse" them in the output configuration?

 

[Bigtrout]

No it doesnt source current it sinks current...what are you trying to run with the db9?

 

[dmolavi]

No it doesnt source current it sinks current...what are you trying to run with the db9?

LEDs to indicate on/off status

 

[dmolavi]

No it doesnt source current it sinks current...what are you trying to run with the db9?

The pico board schematics show that it should be able to source it, if I'm reading it correctly.

 

[Bigtrout]

The pico board schematics show that it should be able to source it, if I'm reading it correctly.

Sorry, im not that familiar with the pico board, its using a different configuration than the uln2803 for outputs.
Yes it appears that you can sink or source current...try checking the reverse box in reef pi

 

[theatrus]

The pico board schematics show that it should be able to source it, if I'm reading it correctly.

The pins route to an N channel MOSFET, they can only sink current at the DB9. You can still use LEDs attached to the DB9, just connect the cathode and supply voltage at the anode side (don’t forget a current limiting resistor). You can wire in parallel with the ADJ relay pack as well.

 

[dmolavi]

The pins route to an N channel MOSFET, they can only sink current at the DB9. You can still use LEDs attached to the DB9, just connect the cathode and supply voltage at the anode side (don’t forget a current limiting resistor). You can wire in parallel with the ADJ relay pack as well.

What do you mean by connecting the cathode and supply at the anode side? Right now, I have the anodes connected to the DB9 GPIO pins and thr cathodes to ground through a resistor.

Should I go from the 12V pin on the DB9 to each anode then to the DB9 GPIO pins from the cathodes?

 

[theatrus]

What do you mean by connecting the cathode and supply at the anode side? Right now, I have the anodes connected to the DB9 GPIO pins and thr cathodes to ground through a resistor.

Should I go from the 12V pin on the DB9 to each anode then to the DB9 GPIO pins from the cathodes?

Yup!

Be sure to calculate current at 12V supply (-Vf)

 

[dmolavi]

Yup!

Be sure to calculate current at 12V supply (-Vf)

Haha yeah. I used a 470ohm resistor..should be enough but I'll double check

 

[dmolavi]

Haha yeah. I used a 470ohm resistor..should be enough but I'll double check

To clarify...I have the LEDs wired in parallel, each with it's own resistor.

 

[theatrus]

To clarify...I have the LEDs wired in parallel, each with it's own resistor.

Are you using a ADJ strip as well? Each LED should have its own resistor, and in parallel with the relay on the ADJ strip, if applicable.

 

[dmolavi]

Are you using a ADJ strip as well? Each LED should have its own resistor, and in parallel with the relay on the ADJ strip, if applicable.

No ADJ strip. It's basically just an array of 8 LEDs.

I'm thinking that the better way is to do two sets of 4 LEDs in series with a 180ohm resistor for each set...

 

[dmolavi]

Yup!

Be sure to calculate current at 12V supply (-Vf)

@theatrus - Before I go and re-wire all this...would this be the correct setup? Resistors are 500 ohm. Instead of going to ground as in the diagram, each cathode would go back to a DB9 pin.

Or would this be a better solution (the connector on the bottom is the DB9...uses 200 ohm resistors, and the two lines to ground are just to complete the circuit, wouldn't need to be on the actual board, correct?):

Regardless of which is better/more correct, either would allow for each LED to be individually switched on/off via the 'equipment' page in Reef-Pi? (I'm not using an ADJ...these are status only)