Thread Tools
Feb 05, 2019, 11:45 PM
Registered User
Thread OP
When we say the IO pins it's about the voltage sent on the SDI, NSEL, SCK etc pins. If the atmega is powered at 5V and no resistors it's not good.

Measuring with a voltmeter directly on the pins doesn't give a correct reading as the voltage isn't constant but will quickly vary (binary data).

The best is to check the power of the atmega directly, but if the RFM VCC is 5V there are all chances that the atmega is at 5V too, as they don't seem to have two separate regulators.

If it's the case then it has the same issue the DTF UHF had. Other OrangeRX modules have the atmega running at 3.3V which is fine.
Sign up now
to remove ads between posts
Feb 06, 2019, 01:20 AM
Registered User
CHOYADO's Avatar
Well, my issues with ULRS are isolated to the ORX 1w receiver. I installed a ORX tx module running as a receiver in my plane and the problem has gone away. I did quite a bit of testing and the RF link recovered from a lost connection every time it lost. (quite gracefully actually)

I think the issue probably relates to the 5v logic coming out of the amtel chip since it is powered at 5v. I will try changing a resistor to bring the voltage down to 3.3 and see if that improves the stability of the RF link.

I was actually getting a little frustrated and thinking about ditching the ULRS system completely but I am content now.
Feb 06, 2019, 01:36 AM
Registered User
Thread OP
If you're happy I'm happy.

This said, if the ORX 1W receiver really sends out 5V on the IO pins I'll remove support for it completely as it's a well known cause of issues.
Feb 06, 2019, 01:55 AM
Registered User
CHOYADO's Avatar
Quote:
Originally Posted by flipflap
If you're happy I'm happy.

This said, if the ORX 1W receiver really sends out 5V on the IO pins I'll remove support for it completely as it's a well known cause of issues.
I checked with my voltmeter. The vcc pins on the ATmega are supplied with 5v. I'll try changing out the R7 resistor and see if that brings the voltage down.
Feb 06, 2019, 02:40 AM
Registered User
CHOYADO's Avatar
I couldn't find a 6.25k SMD resistor in my boneyard so I replaced it with a 7.5k resistor. That resulted in 3.8v coming out of the regulator. Surprisingly everything works now. The ORX 1w receiver (now probably 300mw) will recover gracefully from a loss of signal. If people want to use this receiver, in addition to the modifications already stated they must replace the r7 resistor.

I think this receiver still might be a viable option for someone with the soldering skills. Flip Flap, if you were to officially support it and add it as a target, changing the output pins in the code, the only mod necessary would be changing one resistor. Possible?

P.S. My garage door opener remote doesn't work when ULRS is transmitting. How do I fix that?
Last edited by CHOYADO; Feb 06, 2019 at 02:45 AM.
Feb 06, 2019, 04:33 AM
Registered User
Thread OP
Change channels, or relocate

I can't turn on my lamps (wireless switch) with ULRS on some specific channels. There's no magic...
Feb 06, 2019, 06:24 AM
Registered User
Quote:
Originally Posted by CHOYADO
I couldn't find a 6.25k SMD resistor in my boneyard so I replaced it with a 7.5k resistor. That resulted in 3.8v coming out of the regulator. Surprisingly everything works now. The ORX 1w receiver (now probably 300mw) will recover gracefully from a loss of signal. If people want to use this receiver, in addition to the modifications already stated they must replace the r7 resistor.

I think this receiver still might be a viable option for someone with the soldering skills. Flip Flap, if you were to officially support it and add it as a target, changing the output pins in the code, the only mod necessary would be changing one resistor. Possible?

P.S. My garage door opener remote doesn't work when ULRS is transmitting. How do I fix that?
Very well seen CHOYADO, your idea works on the RX 1w receiver, we can finally use it in the absence of flipflap publish the update and add it to your configurator so that the modification of the RX is very simple.

Greetings from Spain.
Feb 06, 2019, 06:30 AM
Registered User
Quote:
Originally Posted by CHOYADO
The GPIO_1 pin is 3.3
Yes because GPIO_x belongs to low voltage RFM part (Si4430 chip ?) powered by onboard 3.3V regulator.

Quote:
Originally Posted by CHOYADO
That resulted in 3.8v coming out of the regulator. Surprisingly everything works now.
Good news, thank you. I planned to lower Atmega voltage today but you was first
Last edited by RD00; Feb 06, 2019 at 06:43 AM.
Feb 06, 2019, 06:45 AM
Registered User
Quote:
Originally Posted by flipflap
Change channels, or relocate

I can't turn on my lamps (wireless switch) with ULRS on some specific channels. There's no magic...
Will you add support for this receiver to the configurator with correctly configured outputs? These receivers were bought by a lot of people at the recent sale of Hobby King. Thx!
Feb 06, 2019, 07:25 AM
Registered User
I'm not sure to understand what must be lowered
I just check GPIO pin of an Orange RX 1W with a scope and it's 3.3V.
So which power input is an issue at 5v ?
And so what could be the issue with wolfbox rx 100mw where link can be loss (led flashing but nothin is working) ?
Feb 06, 2019, 07:25 AM
Registered User
Quote:
Originally Posted by flipflap
This said, if the ORX 1W receiver really sends out 5V on the IO pins I'll remove support for it completely as it's a well known cause of issues.
It is about 20+ receivers purchased in this thread and probably hundreds over the whole RC community. Is it good reason to drop support just because it needs some DIY (much less then ULRS DIY boards)?
Feb 06, 2019, 07:55 AM
Registered User
Quote:
Originally Posted by urlu75
I'm not sure to understand what must be lowered
I just check GPIO pin of an Orange RX 1W with a scope and it's 3.3V.
So which power input is an issue at 5v ?
And so what could be the issue with wolfbox rx 100mw where link can be loss (led flashing but nothin is working) ?

Hi again, the proposed by CHOYADO consists in lowering the power of the entire receiver to 3.8v by simply changing the R7 resistor to another 7.5k, but this only applies to the Orange RX 1w.
The problem in wolfbox rx 100mw may be the same, but you have to know what changes would be necessary to solve the problem in wolfbox rx 100mw.

Greetings from Spain.
Last edited by RICKY24; Feb 06, 2019 at 09:45 AM.
Feb 06, 2019, 08:12 AM
Registered User
Hello again, I have made the modification differently, it is something more complex, but it is still very easy.
My proposal is to continue feeding the RFM module to 5v and the rest of the circuit to 3.3v or almost ...

The modification consists in cutting the track next to the capacitor C3 that goes to TP11 and this isolates the 5v cable from the rest of the circuit, then one these two points with two diodes 1N4148 in series with the cathodes in the direction of the TP11, but instead of use the TP11 i am plugged in the capacitor C1 on the side that looks at the ATMEGA since it is easier to weld there and they are the same point (this already feeds the entire circuit to 3.5v approximately).

The next thing I do is desolder the power pin of the RFM (VCC) and finally weld a wire from the power pin of the RFM to the capacitor C3, so the RFM module is fed at 5v and delivers more power.

I attach photos of the process.

Greetings from Spain.
Last edited by RICKY24; Feb 06, 2019 at 09:44 AM.
Feb 06, 2019, 08:33 AM
Registered User
Sebastos's Avatar
Good Job RICKY24!
Feb 06, 2019, 11:30 AM
RX5
RX5
Registered User
My quick reply to this voltage issues with the commercial units , if atmega is running at 5v , better check circuit/board of the data lines have resistors in series going to RFM.

If none then better add one (reference schema from ulrs mini)

On the other hand, is the receiving FC 5v tolerant with ppm input? (From the 5v atmega)

Or is it a big problem if a code running @16MHz be run at 3v3 supply?


Quick Reply
Message:

Thread Tools