FPVLAB

image
Page 1 of 29 12311 ... LastLast
Results 1 to 10 of 288

Thread: PPM to Analog Converter (For EzUHF RSSI)

  1. #1
    Michael Mictronics's Avatar
    Join Date
    Jul 2011
    Location
    Bavaria, Germany
    Posts
    1,010

    Lightbulb PPM to Analog Converter (For EzUHF RSSI)

    Finally I finished the new batch of EzUHF RSSI to analog converter. The hardware is a new development and uses a different approach to convert RSSI and Link Quality to a analog signal output.

    The new v2 connects to the EzUHF RX by EzBus to read RSSI+Link Quality and therefore will not occupy any servo channel. Furthermore RSSI and Link Quality are available in parallel, and you can decide what signal to show on your OSD. A second feature is a jumper to reduce the output voltage swing from 0-5V to 0-3.3V to be compatible with OSDs which accept only 3.3V analog inputs.

    What you get:
    Click image for larger version. 

Name:	complete.jpg 
Views:	1687 
Size:	46.5 KB 
ID:	18282
    The board is plug-and-play and comes with all required cables. A 20cm EzBus cable to connect the EzUHF RX on one end and a 50cm cable with open end to connect your OSD.

    The only required setup is the output voltage jumper as shown in the image below. By default the jumper is set to 0-5V output swing.
    Click image for larger version. 

Name:	board_v2.jpg 
Views:	4447 
Size:	234.0 KB 
ID:	18283
    Wiring colors for OSD connection:
    red - Supply voltage input, 3-5V, Absolute maximum 5.5V!
    black - Ground
    orange - RSSI output voltage 3.3-5V depending on jumper setting
    yellow - Link Quality output voltage 3.3-5V depending on jumper setting
    brown - Ground

    Warning: It is NOT possible to connect the converter in parallel to the EzOSD and have them both talk to the EzUHF RX!!! You will risk damage on your IMRC equipment and/or the converter!

    Info about the older version can be found here: http://www.mictronics.de/projects/pp...log-converter/
    Last edited by Mictronics; 9th February 2013 at 02:18 PM.

  2. #2
    Navigator
    Join Date
    Jan 2012
    Posts
    99
    Very nice, thank you for sharing! I can see a lot of resistors in your design - are those intended for the second use case (PPM->PWM-converter?).

    [Edit]
    Awww I missed the fact that the AtTinys do not have a built-in D2A, sorry
    Last edited by after.burner; 29th January 2012 at 11:39 AM.

  3. #3
    Michael Mictronics's Avatar
    Join Date
    Jul 2011
    Location
    Bavaria, Germany
    Posts
    1,010
    The resistors are the R2R network, the simplest way of digital to analog conversion.

  4. #4
    Bazinga! Maximus's Avatar
    Join Date
    Sep 2011
    Location
    Ireland
    Posts
    2,931
    Hi Michael
    I assume this would work with the DragonOSD, right? Is there any calibration to be done, and how accurate is the output?
    I'll take one if you can confirm it will work well with the DraonOSD.

  5. #5
    Bazinga! Maximus's Avatar
    Join Date
    Sep 2011
    Location
    Ireland
    Posts
    2,931
    Another question: How does it connect to the EZUHF Rx? I'm using PPM out on Ch1 which goes into the DragonOSD, and also use one other channel directly to a tilt servo. Where does the PPM>Analog Converter fit in?

    Edit: I think I found the answer in the other thread. It uses the RSSI needle output on a spare channel which is chosen through the ImmersionRC software. Correct?
    Last edited by Maximus; 30th January 2012 at 04:53 AM.

  6. #6
    Michael Mictronics's Avatar
    Join Date
    Jul 2011
    Location
    Bavaria, Germany
    Posts
    1,010
    Correct.

    A calibration might be necessary but depends on the DragonOSD. I don't have one so can't answer this in detail.

    From the technical facts the converter will translate the PPM signal into an analog voltage. See timing constrains in the first post.
    Digital resolution is 8 bit, timing resolution 4us, voltage resolution 19mV.

    ---
    There is a RSSI calibration procedure described in the DragonOSD manual, page 71. Integration seems to be simple, so I don't see a problem with the converter here.

    Personally I prefer the EzUHF link quality output since this will give you already an indication of 0-100%. Also from previous range tests I would say it's more meaningful than the RSSI value. You can have a good link quality even with a low RSSI. But with high interferences you can have a high RSSI but bad link quality.
    Last edited by Mictronics; 30th January 2012 at 05:21 AM.

  7. #7
    Bazinga! Maximus's Avatar
    Join Date
    Sep 2011
    Location
    Ireland
    Posts
    2,931
    I see what you're saying about the link quality vs RSSI output. I assume this unit only does RSSI out, right?

  8. #8
    Michael Mictronics's Avatar
    Join Date
    Jul 2011
    Location
    Bavaria, Germany
    Posts
    1,010
    What unit? The converter will translate any PPM signal you feed in.
    On the EzUHF RX you can enable either RSSI needle out, Link Quality needle out, or if you use two channels, both together. Just connect the converter to either needle output and you get a corresponding analog voltage.

  9. #9
    Bazinga! Maximus's Avatar
    Join Date
    Sep 2011
    Location
    Ireland
    Posts
    2,931
    Ah I get it, thanks! I didn't know that I could choose to convert either Link Quality or RSSI. So in the end it's a software setting which determines which one will be converted.
    Sending you email now to order.

  10. #10
    Michael Mictronics's Avatar
    Join Date
    Jul 2011
    Location
    Bavaria, Germany
    Posts
    1,010
    Just a note about EzUHF RSSI and link quality:

    The RSSI needle output will produce a inverse proportional voltage indication. A low/bad RSSI will result in a high voltage since the PPM signal is directly related to the absolute RSSI value in dBm.

    The Link quality needle output generates a proportional voltage. So 0% link quality means low voltage.

Page 1 of 29 12311 ... LastLast

Similar Threads

  1. Splicing ezUHF wire into ezOSD for RSSI. Question.
    By BayAreaCrasher in forum ImmersionRC
    Replies: 23
    Last Post: 29th November 2015, 05:25 PM
  2. EzUHF RSSI display options with EzOSD?
    By nk4787 in forum ImmersionRC
    Replies: 6
    Last Post: 16th February 2012, 06:23 PM
  3. EZUHF/OSD RSSI problem
    By Ratty in forum ImmersionRC
    Replies: 3
    Last Post: 31st January 2012, 09:52 AM
  4. EzUHF RSSI Output
    By Mictronics in forum ImmersionRC
    Replies: 0
    Last Post: 13th December 2011, 08:31 AM
  5. EZUHF- EZOSD RSSI connection
    By pesbra in forum ImmersionRC
    Replies: 7
    Last Post: 13th December 2011, 01:19 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •