PPM RC to USB Interface

Yof · Post by **Yof** » Mon Nov 20, 2006 6:14 pm

How low voltage can the PPM signal have for this device?

Yof · Post by **Yof** » Mon Nov 20, 2006 10:00 pm

My Mx-12 is almost working with the USB interface now. It has -1.5V as PPM signal. But i switched the polarity and it started to work.

The main problem now is the channel mapping. In Aerofly Pro Delux the x-rotate channel (Rudder) is not found. But i can see it working in my controle panel. The same problem excist with channel 6 (Gear Switch).

How come the channel disapear in the program?

Yof · Post by **Yof** » Mon Nov 20, 2006 10:03 pm

I'm using ppJoy with another radio. And there are all the channels okay. So i gues there is some problem with the USB Driver?

Yof · Post by **Yof** » Mon Nov 27, 2006 5:22 pm

Only want to tell that everything s working now.

Post by **christian** » Mon Nov 27, 2006 5:48 pm

Hi Yof,
glad to read that it works now :-)

Can you please post more details which may be helpful for others who have similar problems? What caused the problem and how did you fix it?

os · Post by os » Thu Nov 30, 2006 11:32 pm

christian wrote:Can you please post more details which may be helpful for others who have similar problems? What caused the problem and how did you fix it?

I had the same problem with AFPD and also thought that some channels do not work at all.

In fact, AFPD requires its own controller calibration. Without it some channels may look like dead ones. Simply calibrate them and all should be fine.

John · Post by **John** » Mon Dec 11, 2006 9:12 am

Hi all
I think problem is the voltage(VCC) of ATMega8 is too low.Becuaes in the data sheet its operting voltage is

ATMega8 = 4.5-5.5 V
ATMega8L = 2.7 - 5.5 V

In the circuit of this project use ATMega8 not ATMega8L which use 3.3V for VCC

Sory if I mistake.

John

Post by **christian** » Mon Dec 11, 2006 12:06 pm

I doubt that the supply voltage has any influence. Yes, it's true that the ATMega8 is not specified for 3.3V operation.

However, parts of the data sheet (such as figure 121 "Active Supply Current vs Vcc" in section "ATMega8 Typical Characteristics") suggest that the same parts can be operated over the entire voltage range. My own tests showed that the "normal" parts usually work down to below 2V supply.

The "L" probably only means that the parts have been tested with low voltage or that they have been optimized for this voltage range.

makaveh · Post by **makaveh** » Wed Dec 27, 2006 10:35 pm

Hi,

Is there anyone to have the schematic diagram of RC (Futaba FF7 5 pin DIN) to USB Interface for Flight Simulator Progs in PDF format or any other format with IC Prog files ?

My email: makaveh@accir.com

Kaveh

os · Post by os » Wed Dec 27, 2006 10:40 pm

If you ask for pin assignment diagrams then here are two very useful resources which have almost all you need:

http://www.mftech.de/buchsen_en.htm
http://users.belgacom.net/TX2TX/tx2tx/e ... 2txgb1.htm

os · Post by os » Fri Jan 26, 2007 10:15 am

I've got some questions regarding my project via email but prefer to answer here to not duplicate them again and again:

And waht are the differents between the hex files from Rc-design (v1- v4) (VJoy) and yours??

The software from rcdesign.ru and this project are completely different. The only common is an idea and schematic (which was chosen to simplify drop-in replacement of firmware).

In general, differences are, at least:

- RCU has modular structure for easy input and/or output interface replacement;
- RCU has much more accurate PPM measurement than VJoy;
- RCU supports number of input data filtering compilation options to improve accuracy of PPM pulse measurement;
- RCU optionally provides servo tester output (converts one PPM input channel into servo output);
- some versions of VJoy firmware do not work under Windows 9x/Me, special version of firmware was required for those systems (due to HID Report Descriptor specifics);
- some VJoy firmware supports hardware-mapped joystick buttons which are not supported by RCU;
- RCU does not support channel mapping via NVRAM;
- VJoy is written in assembler but RCU is written in C;
- VJoy source is not available, but RCU is based on open-source USB driver and is also open-source.

What can I make in the source file, that if I plug in my USB Interface into my PC the USB device are detected as XXXX-USB and not VJoy ??

This project does not use "VJoy" name. This 4-character name was used in the rcdesign.ru firmware due to limitations of USB driver used there. AVR-USB driver does not have such limitation, so name is different and longer.

To change any of USB device parameters, including device name, you have to update some USB descriptors in the source and recompile the firmware.

I've now downloaded IAR but If I click on make , the programm give me the fallow error:

Fatal Error[Cp001]: Copy protection check, Your time limited license has expired - You must register NOW to get the permanent key in order to continue using this prduct!!

What is the problem??

This question was already answered here.

Guest · Post by **Guest** » Mon Feb 12, 2007 9:58 pm

Yof wrote:My Mx-12 is almost working with the USB interface now. It has -1.5V as PPM signal. But i switched the polarity and it started to work.

The main problem now is the channel mapping. In Aerofly Pro Delux the x-rotate channel (Rudder) is not found. But i can see it working in my controle panel. The same problem excist with channel 6 (Gear Switch).

How come the channel disapear in the program?

DARRELL · Post by **DARRELL** » Fri Apr 24, 2009 12:32 pm

im looking for a usb interface to go with my e-fly 2.4 ghz dsm transmitter can anyone help me with this problem please

os · Post by os » Fri Apr 24, 2009 1:44 pm

DARRELL wrote:im looking for a usb interface to go with my e-fly 2.4 ghz dsm transmitter can anyone help me with this problem please

You have not mentioned exact transmitter model. In case if it is E-Flite LP5DSM, it looks like the Tx does not have PPM output because internal DSM2 Tx module uses serial protocol rather than standard de-facto PPM. You have to rewrite the firmware of USB interface to "learn" it to receive serial input from Tx. Or you can just compile the firmware in ADC mode (see sources) and connect ATmega8 ADC directly to LP5DSM potentiometers (you even do not have to disconnect original circuit).

I do not support this project for a long time so I am unable to provide more techical details. If you unable to make own schematic and/or recompile the firmware - it could be better to get some of ready-to-use USB simulators, say, this ($22.92 + free shipping worldwide).

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