Flashing Frsky-modded 9x with transmitter power on

DHDSP · Post by **DHDSP** » Mon May 07, 2012 6:31 am

Last week I modded my 9x with an frsky rf-module, and yesterday I did the swicth mod to prepare for the telemetry mod.
After flashing with companion9x and the frsky option selected, everything seems to work. Yeah !

Now for my problem: I found out that my AVRISP mkII needs to have the processor powered to be able to programm/flash the device. So, in short, I have to have my transmitter powered up to programm it.
I read somewhere that after having the telemetry mod done, you should not programm/flash while having the transmitter powered up - because the telemetry data interferes with the data stream from the programmer.

I know the solution is to either
1. make my AVRISP mkii power the controller
2. or get an USBASP

But in the mean time I would still like to be able to flash my radio, so here's...

...my question:

Is anyone doing this (telemetry mod + powered-up flashing)? And if so, where should I add the resistors (Frsky rx/tx), and what is the right value?

Post by **Rob Thomson** » Mon May 07, 2012 7:40 am

I believe the actual risk her is that if the receiver is on, the telemetry signal being sent down the miso and mosi lines can result in corruption of the firmware.

In the wiki diagrams and docs.. I believe there is a resistor on either the miso or mosi line that limits this risk? ( I stand to be corrected)

Solution.... Don't turn your rx on when flashing! Or just unplug the module

Sent from my iPhone using Tapatalk

Post by **jhsa** » Mon May 07, 2012 8:38 am

I do it all the time. I disabled the power on the programmer so I can always do it with the radio on. I had no problems till now and have my radio for over an year.
I did this telemetry mod..

er9x.googlecode.com/svn/trunk/doc/TelemetryMods.pdf

It is the telemetry by Mike.. It is on the wiki

gohsthb · Post by **gohsthb** » Mon May 07, 2012 11:33 am

Yes this is one of the reasons you add the resistors between the atmega64 and the rs232 converter. The programmer signals will have priority.
-Gohst

gruvin · Post by **gruvin** » Sat Aug 04, 2012 1:36 am

The main thing with this is to make sure the no receiver is switched on, bound and sending any Fr-Sky telemetry. If telemetry data is coming in, it can and will mess things up. Otherwise, you should be fine.

Oh and -- if you use a MAX232 instead of the pseudo-RS232, transistor based level converter Gruvin uses and prefers (standard on theG9X v4.x boards) then you will have additional issues to consider. I guess this is the the reason for the resistors, mentioned in a previous post here. Certainly, something will be needed, otherwise the MAX232 will tie up the MISO pin.

I use an Atmel AVR ISP mkII as well, when developing/testing code, because it so fast. But I just use the gProg board for open9x firmware updates, as it's so convenient.

Post by **Kilrah** » Sat Aug 04, 2012 7:50 am

I always flash with radio on and module in, and sometimes with a receiver on too. as long as you fitted the resistors as shown between the frsky module and the mainboard pads, no problem.

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