I have a design for an electronics workbench that has 2 Arduino's (a Mega and an Uno), and several component testers that have Atmega328 MCU's at their core, and I was wondering if there is a way to have one BT HC-05 module that I can switch between the devices to program them individually one at a time (rather than having 4 BT modules ie. one for each).
They can share a common 3.3V rail, ground, and LED indicator pins as all the devices share the same power and ground. AFAICT the only 3 bus lines that need to be switched between the devices are the RST (using the HC-05 pin 32 & 100nF Capacitor), TX & RX lines. What components & circuit can I use to select and switch these three bus lines to the devices I wish to program?
The basic circuit for one device with one BT module is here: -> Arduino BT programming circuit
Though I will be using the bare module, not the version on a 5V adapter board.
Could I use 3 quad optocouplers (one each for the 3 lines that need to be swiched between the 4 devices) and some mechanism to select when to turn the one I want in each OC package on? I understand how to turn on the OC (probably with the ATMEGA328 or a latching logic gate triggered by a push button, but would I need any components around the OC on the data line side (the EC side of the OC) or would it be pretty much a simple placement of the quad OC transistor side into the circuit? I'm stretching my knowledge here a bit, but you have to learn somehow I guess.