I decided to go ahead and get a couple of Raspberry Pi Zero breadboards to see if I can solder the required resistors and the level shifter, along with a couple of breadboard electrical connectors. I have it in mind to run power to the RPi breadboard and then connect the 850LM to the breadboard as well. That way, the power goes to one location and is distributed from there. It would be nice if I could find a simple board that provides 5v power without being huge.
That being said, I fritzed a layout using the Adafruit quarter proto-board. I used pretty much the same connections, except that I purposefully put most of the power traffic cop on the proto-board. So there are now five entities that will need to go into a 3D print, counting the LiftMaster 850LM. The fritzing layout (not showing the 850LM) follows:
This was pretty much as simple as I could get it. I am using a slightly different Buck-Converter than the Adafruit one shown in the Fritzing diagram, but the principle is the same (9v -> 5v power for the RPi Zero W). I am assuming at this point that when the relay switches and drops the voltage to zero that the 9v power will not drop below the point where the RPi will "brown out." The resistors are 220 ohm which will give a draw of 40 ma from the 9v power supply during the relay switch. Note that the 850LM channel 1 is tied to GPIO4, channel 2 is tied to GPIO5, and channel 3 is tied to GPIO6 on the RPi Zero W. The fritzing RPi is a Zero but that is okay for illustration purposes since the GPIO pinouts are the same. The use of a RPiZW is for wifi access in my IOT vlan.
This was pretty much as simple as I could get it. I am using a slightly different Buck-Converter than the Adafruit one shown in the Fritzing diagram, but the principle is the same (9v -> 5v power for the RPi Zero W). I am assuming at this point that when the relay switches and drops the voltage to zero that the 9v power will not drop below the point where the RPi will "brown out." The resistors are 220 ohm which will give a draw of 40 ma from the 9v power supply during the relay switch. Note that the 850LM channel 1 is tied to GPIO4, channel 2 is tied to GPIO5, and channel 3 is tied to GPIO6 on the RPi Zero W. The fritzing RPi is a Zero but that is okay for illustration purposes since the GPIO pinouts are the same. The use of a RPiZW is for wifi access in my IOT vlan.
