Working TRRS iPhone cable for BaoFeng UV-5R+
I got TX and RX both working with PocketPacket, but it took a little experimentation. Here's my schematic
BaoFeng to iPhone TRRS Cable 2.png
I used a small cap and 3 resistors to trick the iPhone into thinking a microphone was connected. I snagged that part of the schematic from http://www.creativedistraction.com/d...using-arduino/
I used a small decoupling cap on the speaker out of the radio. Not sure why this was necessary, but in my testing it made receipt of packets much more reliable.
I used a diode to trick the radio into not activating PTT while still (sorta) connecting the grounds. This is certainly a hack, and I'm very open to better ideas.
On my radio, volume is maxed, vox is set to 2, squelch is set to 1. On my iPhone volume is also maxed.
Feedback is much appreciated, I'll probably do a board design that plugs straight into the BaoFeng once I get the design hammered out.
- KK6GIP (John)
Last edited by johnboiles; 09-04-2013 at 10:42 PM.
Reason: Updating Schematic
Did you try simply not connecting the ground at the mic jack of the radio? If that doesn't work, how about a cap?
Thanks - i am just about to embark on the same project as soon as the radio shows up.
I was abel to get pocketpacket to work as well. Took a bit of configuration, but I suppose if it just worked to transmit over the radio right out of the box, that could really cause some problems.
I ended up just plugging in a headphone into my iphone, holding the ear bud up to the mic of the UV5R, holding the PTT while I flipped the "Transmit" flag on the iphone app. Worked like a charm. The speaker on the iphone itself wasn't enough to transmit a clean packet, but seems that the headphone volume was loud enough.
The nearest digipeater is only a mile away, so I do have that going for me as well.... with further distances, there might not be enough clean signal to transmit a valid packet.
Yep - just let the ground float on the mic side - audio out iPhone to tip - of works just fine. No hum - headphone level full on phone and vox at 3, RX audio from radio 4 clicks above zero. Turn off power saver. I am sending and receiving on 144.39
Originally Posted by Cz10
I followed John's design and wired the three resistors and two capacitors. I tested it by transmitting to the Baofeng and having the inline audio recorded by Voice Memo. It seems to work though PocketPacket has yet to decode any packets for me.
On the Baofeng mic line, what kind of diode should I use? I put in a small switching diode but I'm still having problems when I transmit.
I'm having problems with the vox. It's activated by the iPhone but after the transmission, it hangs for several seconds.
Another oddity I'm experiencing is that the Baofeng will respond to an incoming radio signal by transmitting silent audio.
This is proving to be an interesting mystery.
So, does anybody have an idea what kind of diode I should use?
Any theories on what's causing the vox to hang? (When not connected to the iPhone, the vox functions as it should.)
Any help would be appreciated.
Good gosh, I got it working!
I see that John dropped the diode from his design. That's good to know.
I mounted the 3 resistors and the two capacitors on a little piece of cardboard and soldered the connections. Before, when I had it connected with just alligator clips, I had all kinds of strange problems.
Contrary to what others report, one thing I've found is that I need to connect to the Baofeng mic ground. When I connect to the Baofeng speaker ground, it takes a long time, maybe 15 seconds, for vox to drop a packet transmission. I don't know if that's because of a longer duration of audio coming from the iPhone or if something else is going on. So, far, it doesn't seem to matter. The connection to the mic ground seems to be working OK.
My thanks to John for coming up with the circuit design and sharing it with us.
I hope someday somebody will find a way for an iPhone to function as a TNC for packet BBS and/or Winlink. That would be really nice.
This is the best info on the net for doing this. I will have to head back to the electronic parts store to make the cable described here. I'm new to APRS I'm wondering what settings for Pocket Packet you all are using.
About the app itself:
I've not had any luck with it transmitting the APRS by holding radio mic next to iPhone.
Here are my Settings let me know if anything looks drastically wrong?:
I've entered my callsign
Report Altitude: ON
Symbol: Set (Jeep)
Comment: Testing Iphone RX
Transmit Timer: Varies (I've tried multiple and find if you move slider it forces a transmit)
View Options and Messagingall defaults
APRS-IS Connection Settings
Enabled: "Off" (when this first two are "on" it reports to APRS network using cell coverage)
Passcode: my code is entered
Audio Modem (this is where it counts)
Digipeater Path: Via1: "WIDE1-1 Via2: WIDE2-1 VIA3&4 are empty
I've been using Open APRS for a while but that is relying on the cell data not RF so I wanted to get this RF thing setup and running using Posket Packet and eventually on an old Iphone3gs I have and dedicate it to a "go" bag for bicycle mobile operations.
Originally Posted by k5non
Your settings looks similar to what I have. I've found that the speaker on the iPhone doesn't output enough audio to transmit over the radio. Take a pair of headphones, plug them into the iPhone, and hold the headphone up to the radio mic... turn the volume way up on the iPhone
I have this circuit working on both TX and RX with my iPhone5, and have seen my callsign show up on another APRS monitoring source so I know the transmissions are being picked up and passed along. YAY! Many thanks to John for this circuit.
Originally Posted by robtwright
I found that it will work only on RX on my iPad. When I connect the mic part of the circuit the radio begins switching back and forth constantly between TX and RX even if I don't have transmit enabled in the app. On the iPhone everything works as it should. That's OK with me; it's the iPhone I intend to use it with anyway.
As to the VOX hang time, I have about 3 or 4 seconds of it, and I guess I'll have to live with it as I don't think it can be fixed by any setting I've found. I also had the silent audio transmissions you refer to until I set the VOX higher--to 4. I theorize there was transient/stray audio from the iPhone that was keying it.
Anyway, the only problem I have now is that I'm playing with it all the time (grin).
Here's a photo of my iPhone5 on a little stand I made, with John's circuit strapped on the back: