[chirp_devel] VX2r

[Andrew Errington]

On Sun, 12 Feb 2012 00:06:59 Dan Smith wrote:
> > I wonder if I need a diode between the Tx and Rx lines.
>
> Nope, you don't. Just tie the TX and RX lines together and feed them to
> the radio's data pin. Make sure your data and ground lines aren't switched.
>
> Open a serial terminal (like minicom) and start the clone from the
> radio. See if you see any data, especially like AH0XX. If not, there's
> no communication. If you do, but it's garbled, then search for a
> suitable baud rate. If you see AH0XX, then you're off to mess with CHIRP
> code.

Ok, I tried gtkterm with all available baud rates, from 300 baud to 115k, all 
with 8 bits and no parity.  Nothing.  I would have thought the baud rate to 
be well-known, but I can't find any information about it on the web.

The loopback still works.

I will try another 4-pin cable.  And I will try a diode between Tx and Rx.  It 
seems to me that the radio is trying to pull down the data line, but the PC 
Tx line is pulling up (idle).

I also wonder about using 3.3V.  I measured the idle state of the radio's data 
pin and got about 3V.  This made me nervous about using a 5V TTL interface, 
so I modified the FTDI board to use 3.3V.  Many of the interface circuits on 
the web use 5V (or some hacked power supply from the serial port control 
lines).  Perhaps I should go back to 5V.  I will be making a 5V interface 
anyway, for the FT817ND.  I will use the same 3.5mm stereo socket for 
Tx/Rx/Gnd and make up a cable to the '817 data connector.

73,

Andrew
ZL3AME