Originally Posted by Boagy

I notice that FrSky 4, 7 & 8 channel receivers have a operating voltage range of 4.8 - 6 volts.

Does this rule out the capability of using 2 cell LiFePO4 packs (6.6v) to power the receivers.

Steve

I should have been clearer. I was referring to the old Rx's. I realise the new Rx's will have higher operating voltage (3v - 16v).

Thanks for the input.

Steve

Well, we are talking about 3 different product lines:
- the actual line, that is on sale right now, you said they are speced as 4.8-6V, probably you are right, and I can't speak about them
- the near future (this week ?) telemetry enabled line, which are speced as 4-7.2V
- the future HV (High Voltage) line, non telemetry only, so far, probably on sale in August, rated as you wrote above, up to 16V. There is a very small possibility that the 8ch receiver from HV line have dual power port, as Hitec.
There is no HV and telemetry announced so far, as I know.

If the telemetry Rx can handle 2 LiPOs, that would be good enough for me

Originally Posted by Fly2High

If the telemetry Rx can handle 2 LiPOs, that would be good enough for me

Note that per FrSky's compatibility table, the telemetry-capable Rx only works with the telemetry-capable Tx.

= Mike

Originally Posted by iter

I wonder about the PPM voltage the FrSky module expects.

I have 2 limit cases in mind:

1. Driving the module from a sound card output: 1.2 volt
2. Driving the module from a PPM inverter a-la

Various reports suggest that the module is happy with signals going either way (i.e. it does not require inversion regardless of your transmitter's PPM polarity).

The output from your soundcard may be a bit marginal. I don't have the DIY module handy to check, but if I had to guess I'd expect they're using a passive voltage limiter protecting a 3.3v logic input.

Logical 1 for low-voltage CMOS is usually half the supply voltage, or 1.65v in the 3.3v case. You should check the MSP431 datasheet.

= Mike

I have an antenna broked (8ch Rx), where can I by a new one for replacement?

See Robbe Futaba replacement antennas, two for 10 Eur or so.
http://www.europemodels.eu/src_R606-6014/

Originally Posted by DrZiplok

Various reports suggest that the module is happy with signals going either way (i.e. it does not require inversion regardless of your transmitter's PPM polarity).

Check.

Originally Posted by DrZiplok

The output from your soundcard may be a bit marginal.

It works with Spektrum, Futaba and Hitec modules. No response so far from the FrySky module.

Originally Posted by DrZiplok

I don't have the DIY module handy to check, but if I had to guess I'd expect they're using a passive voltage limiter protecting a 3.3v logic input.

Logical 1 for low-voltage CMOS is usually half the supply voltage, or 1.65v in the 3.3v case. You should check the MSP431 datasheet.

I am not clear on your sugestion. I can interpret it as a recommendation to use an op-amp to bring the signal up to 1.65v, or an observation that FrSky modules uses one.

Ari.

...

A guess that 1.65V is the Frsky pulse trigering level, thus an input swing under this value could be not sensed.

Originally Posted by iter

I am not clear on your sugestion. I can interpret it as a recommendation to use an op-amp to bring the signal up to 1.65v, or an observation that FrSky modules uses one.

Ari, sorry I wasn't clearer.

I would use a level shifter of some sort to convert your 0/1.2v swing up to 0/3.3. If you use an op-amp, be sure to configure for plenty of hysteresis, as the range for logic zero is fairly small. Alternatively, a level shifter specifically designed for interfacing between 1.2 and 3.3v circuits would do the job.

http://www.maxim-ic.com/app-notes/index.mvp/id/3007

It would be good to hear from Jonathan or one of the other FrSky technical folks re: the actual input levels supported by the module.

= Mike

Are two-way modules/receivers on their way to the dealers? None of the ones I've visited online have the telemetry systems in stock. I am eagerly awaiting these products, and like others don't want to spend money on one-way tx modules at this point.

Originally Posted by RENATOA

You have pictures of the uncased module in the other thread, devoted entirely to telemetry stuff, done by some beta testers.
It is very accesible to DIY, actually me too I am using a mockup consisting in using a JR uncased module board in the back module hole of a Futaba 9C.

Hey Renato, my beta test Futaba Telemetry module (and RX) has now been 'hacked' into a friends Turnigy 9X TX. No problems, but for making sure the +12V is swapped to the correct pin. He knows he's only ever got the one orphan beta RX for it but was still keen to try it.
The main point is that the module took the inverted JR logic and didn't care... Nice.

Martin

Originally Posted by samc99us

Are two-way modules/receivers on their way to the dealers? None of the ones I've visited online have the telemetry systems in stock. I am eagerly awaiting these products, and like others don't want to spend money on one-way tx modules at this point.

I believe they are ready. It's worth waiting a little longer.

Originally Posted by DrZiplok

Ari, sorry I wasn't clearer.

I would use a level shifter of some sort to convert your 0/1.2v swing up to 0/3.3. If you use an op-amp, be sure to configure for plenty of hysteresis, as the range for logic zero is fairly small. Alternatively, a level shifter specifically designed for interfacing between 1.2 and 3.3v circuits would do the job.

http://www.maxim-ic.com/app-notes/index.mvp/id/3007

It would be good to hear from Jonathan or one of the other FrSky technical folks re: the actual input levels supported by the module.

= Mike

Hi Mike,
That should be above 1.65V.

Regards!
Eva