I’m using Arms22 softmodem library to communicate with my phone over the audio interface. I want to send the output signal from my arduino over a wireless audio transmitter connected to the input on the phone to make the device portable. The transmitter’s data sheet claims it will accept a 1Vpp input, its designed as a “line in” for audio. The soft modem breakout board I have conditions the arduino output to safe levels for a microphone jack. My confusion is if I put the breakoutboard on the receiving end is it safe to just connect the digital out from the arduino to the wireless transmitters line in? If I put the breakout board on the TX end would I still need to condition the voltage coming from the RX to be safe to go into a microphone? I’m not sure and don’t want to see the magic smoke....esp out of my phone or transmitter...
I don’t have an osciliscope but do have an 2nd arduino hidden in a completed project I could pull if that could help me measure the levels and determine what will be safe. Maybe its possible for someone more skilled than me to look at the library and determine what the levels coming out of the arduino and if they are safe for the 1Vpp connection on the transmitter...
CrossRoads:
The arduino puts out a 0 to 5V signal. You would need to reduce it via resistor divider if you want your device to only see 0-1V.
Thanks CrossRoads! I guess if the end result is getting the signal to microphone levels I should just lower it to 0-1v on the transmitter end and then from 0-1v down to microphone levels on the rx end? I guess thats my main area of confusion, if I only put microphone levels into the transmitter it should only output those same levels? I'm just scared to fry my phone or transmitter
if I only put microphone levels into the transmitter it should only output those same levels?
No. The input level and output level in absolute voltage terms are not related. Of course if you double the input level then the output level should double but they are not the same.
