serial data with internal mic and speaker

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ea3ihi
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Location: Barcelona, Spain

serial data with internal mic and speaker

Post by ea3ihi » Mon Feb 24, 2020 7:18 pm

How is the internal mic and speaker disabled when you connect a mic to the gd77? Is there a mechanical switch? Is it possible to modify the connectors, maybe by removing the tips to make them shorter, so one can use the internal mic and speaker and have serial data at the same time?

David
EA3IHI - David

VK3KYY
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Re: serial data with internal mic and speaker

Post by VK3KYY » Mon Feb 24, 2020 8:44 pm

It’s a mechanical connection, via the jack sockets which disconnect the internal speaker and mic.

KC7RBW
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Re: serial data with internal mic and speaker

Post by KC7RBW » Mon Feb 24, 2020 11:48 pm

This page on the wiki describes a method to use a speaker-mic while still connected to USB:
https://github.com/rogerclarkmelbourne/ ... e-debugger

G4EML
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Re: serial data with internal mic and speaker

Post by G4EML » Tue Feb 25, 2020 12:16 am

I think, in theory it would be possible to make a cable that did not disconnect the microphone and speaker.

Both Mic and Speaker are on the tip connections of the jack plugs. The USB connections are on the rings with the ground on the body of the earphone.

So if you could make jack plugs with no tips it might be possible to connect the USB without operating the disconnect switches.

If you have a spare programming cable you are willing to sacrifice you could try cutting of the tips of the plugs.

KC7RBW
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Re: serial data with internal mic and speaker

Post by KC7RBW » Tue Feb 25, 2020 12:49 am

G4EML wrote:
Tue Feb 25, 2020 12:16 am
If you have a spare programming cable you are willing to sacrifice you could try cutting of the tips of the plugs.
:lol: I do have a spare and I am very tempted to sacrifice one to this, but perhaps instead I will wait to see if someone else does it first.

ea3ihi
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Location: Barcelona, Spain

Re: serial data with internal mic and speaker

Post by ea3ihi » Tue Feb 25, 2020 9:10 am

Before cutting any wires I will try to find the jacks in an electronic components store, do some testing and if it works build a connector with the 3d printer.

Is this drawing right? if it is, then the data+ is in the tip of one of the connectors, I hope it is not the one that mechanically switchs between the internal mic/speaker and the external.

Image
EA3IHI - David

VK3KYY
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Re: serial data with internal mic and speaker

Post by VK3KYY » Tue Feb 25, 2020 10:25 am

ea3ihi wrote:
Tue Feb 25, 2020 9:10 am
Before cutting any wires I will try to find the jacks in an electronic components store, do some testing and if it works build a connector with the 3d printer.

Is this drawing right? if it is, then the data+ is in the tip of one of the connectors, I hope it is not the one that mechanically switchs between the internal mic/speaker and the external.

Image
I just checked, and that diagram seems to be correct.

So it would not be possible to connect USB and still have the speaker and mic.

I checked the schematic that we have for the GD-77, but it seems to be incorrect as it shows the middle section of both plugs as the USB.
I think Colin may have looked at the schematic

G4EML
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Re: serial data with internal mic and speaker

Post by G4EML » Tue Feb 25, 2020 11:01 am

Yes you are correct, the schematic wrongly shows the USB connection is on the rings.
So it probably can’t be done as I thought.

You would either have to modify the radio by shorting out the socket switch contacts or connect a separate usb cable directly to the board.

ea3ihi
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Location: Barcelona, Spain

Re: serial data with internal mic and speaker

Post by ea3ihi » Tue Feb 25, 2020 12:10 pm

So if I need to open the radio to solder some wires, appart from the USB connection is there another (free, not used during normal operation) bidirectional interface we can use to communicate to the outside world? (i2c, uart....)

And now my crazy idea just in case you want to know what I am looking for....

what about adding wifi to the gd77? maybe we can use a ESP32 or similar microcontroller with wifi to talk to a DMR server, using the talky hardware for all the audio and dmr related tasks but without any RF.

Do you foresee any technical issue that makes it impossible? I know it might be a lot of work but dreaming is cheap. The interface protocol would be actually simpler than the hotspot protocol, just DMR frames in and out in an initial phase and later add the UI to set up all the required parameters for the wifi and dmr host connection.

It would be really practial to just pair your gd77 to your phone wifi and join the DMR network without a hotspot.
EA3IHI - David

G4EML
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Re: serial data with internal mic and speaker

Post by G4EML » Tue Feb 25, 2020 1:31 pm

I looked at this for another reason, I would like to add a remote control option.
Unfortunately I don’t think there are any unused interfaces. There appears to be an I2C port connected to the encryption chip which we are not currently using. It might be possible to use that. But I think the I2C is using a single controller in the chip so extra traffic might cause a conflict.

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