Hi all,

As a follow up to my previous message, just looked at the v6.3 TX/RX circuit.

Normally with the USB to I2C interface connected to the v6.3 TX/RX board, the
SCL line would be pulled up to 3v3 supply via R6, however you would have to have
the main board powered up BEFORE connecting the USB lead to the PC, otherwise
the same problem described before would exist, as the AVR is powered from the
USB +5V supply.

Sounds like the same simple modification I did to my v9.0 RX to solve it would
work.

Break the USB +5V lead (pin 1) to the USB to I2C interface, and take it through
a double pole, double throw switch, along with the +12V supply to the main
board. This now allows you to leave the USB lead plugged in at all times, and
when you operate the switch, both supply rails are activated together, should
solve it.

The other solution is to replace the AVR chip with one using Fred's v15.10
firmware, that overcomes the problem, but does need a little bit of simple
configuration to use it for this application.

Basically you need to disable the 'ABPF' mode which is the default setting in
the firmware to allow use of the PTT and CW1/2 lines.

73, Bob G8VOI


--- In softrock40@yahoogroups.com, "g8voip" <g8voi.reeves59@...> wrote:
>
> Hi,
>
> Can either, or both of you experiencing this problem let, us know which type
of AVR device you have fitted in you USB to I2C interface?
>
> Is it an ATtiny45 or 85?
>
> Most likely it will be the ATtiny45 and therefore have the original v1.4
firmware fitted.
>
> This has a known bug in it which was the cause of the majority of v9.0 RX USB
problems. On plugging the interface in, it requires the 'SCL' line to be pulled
up to +5V, otherwise the firmware fails to run and the device is not recognised
by the PC.
>
> Looking at the circuit, with nothing connected externally, there is no pull up
present.
>
> Something you could try is to connect a resistor 4k7 ~ 10k between U1 pins 2
and 8, SCL to +5V. Do not have anything else connected to either the SCL or SDA
pins.
>
> With the board unplugged, check the Control Panel>System>Hardware
configuration and delete any unrecognised USB devices present, as Alan
suggested.
>
> Re-boot the PC just to be sure, then reconnect the USB lead and see what
happens.
>
> 73, Bob G8VOI
>
> --- In softrock40@yahoogroups.com, "Alan" <alan4alan@> wrote:
> >
> >
> > ----- Original Message -----
> > From: "tmac"
> > Subject: Re: [softrock40] OZ1BXN>Re: AVR I2C not reconized by PC
> >
> >
> > >
> > > then I switched to Rocky. At first, it seemed to be working, and after
> > > about 2-minutes the usb driver started failing (indication on computer).
> > > It would "discover" the usb device, then drop out. eventually, it would
> > > no longer discover the usb device. I rebooted the computer. When I
> > > plugged the usb cable in I got a message that there was an unknown usb
> > > device plugged in. After that, the computer would no longer respond to
> > > plugging in the usb cable..
> > >
> >
> > I have seen something like this a long time ago. I think it was caused by a
> > big ground loop.
> >
> > If there is an "unknown usb device" in "Device Manager" uninstall it. The
> > computer may then recognise the controller and reinstall it.
> >
> > 73 Alan G4ZFQ
> >
>