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Old Aug 26, 2010, 02:53 PM
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Arduino RSSI Monitor (LCD, Bar Graph, %, Batt)

Howdy! Just wanted to show off my first "from scratch" Arduino mashup! Its a 16x2 character lcd that displays the RSSI level from a standard Comtech based vrx in both percentage and a 16 step bar graph.

Nothing too special, but could be handy for those w/o access to expensive antenna tuning equipment but would like to explore building and tuning their own antennas OR just to add a little bling to a ground station!

If anyone is interested in building their own, i'll tidy up the code and write it up proper!

Possible Future Upgrades:
- Battery monitor
- Low voltage alarm
- GPS Last known Transmit Coordinates (APRS DTMF possibly?)
- T-Hunting / Fox Hunting Mode
- Divide the 16 segments into 80 for finer resolution bar graph display
- Full Screen Bar Graph Mode
- Large numbers percentage display mode(using 2 rows to display single characters)
- Auto calibration via REF voltage (if i can find it)
- Simple menu or toggle through modes via momentary switch
- Diversity Video Switching
- Data Logging
- Low Signal Alarm
- Smoothing level control via menu or switches
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Old Aug 26, 2010, 04:15 PM
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Tampa, Florida
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Nice work! A future ability to measure two inputs and switch a video mux to the stronger signal would be great! If you could define that threshold in firmware would allow you to use different receivers as the input.

If you could have four inputs a quad diversity could be built. So cool.
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Old Aug 26, 2010, 04:54 PM
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very good work

I would love to see the parts list for this mod.

I would give it a go in a heartbeat .
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Old Aug 26, 2010, 07:07 PM
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Panama City Bch, FL
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Quote:
Originally Posted by kist2001 View Post
Nice work! A future ability to measure two inputs and switch a video mux to the stronger signal would be great! If you could define that threshold in firmware would allow you to use different receivers as the input.

If you could have four inputs a quad diversity could be built. So cool.
thanx kist2001! the standard arduino has six analog inputs. so... hexaversity would be the limit i suppose.

the unfortunate thing is, im not a programmer, so figuring this stuff out can be a painfully slow process. i think diversity control with threshold could be accomplished with a switch / case statement. shouldn't be too difficult. (famous last words)

Quote:
Originally Posted by witespy View Post
very good work

I would love to see the parts list for this mod.

I would give it a go in a heartbeat .
thanx witespy!

parts list:
arduino (any)
16 x 2 LCD (any w/Hitachi hd44780 or compatible controller)
wire

if you are new to arduino, i would suggest the duemilanove. its pretty much the standard and has usb onboard. the pro mini from sparkfun is a popular board but requires a programming dongle. the rbbb from modern device is probably the cheapest arduino solution. it too requires the programmer.

the lcd is just a common parallel 16x2 character lcd. any Hitachi hd44780 or compatible will work. the one im using in the photo has a 74ls164n shift register backpack on it. the advantage to this is that it allows for 2 or 3 wire connection to the arduino vs the 6 wires for a parallel connection.

i also used a 2.5mm TS jack for easy access to the rssi signal without having to open the case.

cheers!
-sj
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Old Aug 26, 2010, 07:17 PM
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Illinois, USA
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Sonicj,
Nice job. I been always wanting to play with an Arduino. You just gave a great project. Please share the code.
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Old Aug 27, 2010, 06:56 AM
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Very cool. When I asked Sander about RSSI from the ImmersionRC DUO 2400 receiver, here was his response. Having this available in the ground station would help testing in the field. Definitely share the code (and maybe which arduino you used)!

-Tom

From Sander:

Yes, you can tap into the RSSI output of the Rx modules, they're Airwave AWM620 or AWM625, consult their datasheet for the pinout. Just hook up one antenna and leave the other input disconnected, then look at the RSSI output of the Rx that is connected to an antenna, use a high impedance (>100Kohm) DVM to measure the RSSI voltage.

Take caution though that RSSI measurements like that cannot be done indoors or in a urban environment due to reflections and multipathing, you really need to be out in a field with nothing surrounding you when you want accurate results.

Cheers,

Sander.
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Old Aug 27, 2010, 11:27 AM
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Originally Posted by vertcnc View Post
Sonicj,
Nice job. I been always wanting to play with an Arduino. You just gave a great project. Please share the code.
thanx! this should be a good 1st arduino project. i'll try to get the code up later today!

Quote:
Originally Posted by BloomingtonFPV View Post
Very cool. When I asked Sander about RSSI from the ImmersionRC DUO 2400 receiver, here was his response. Having this available in the ground station would help testing in the field. Definitely share the code (and maybe which arduino you used)!

-Tom
thanx tom! any arduino will work. some might be a little easier to work with than others. the duemilanove is the board im prototyping with and offers the most compatibility with other projects.

i messed around with big numbers and got them to display ok, im just not certain how to call them up. also played around with a simple menu but decided to put that aside for a min. i figure a battery monitor with low voltage alarm would be the next most sought after function so im working on that at the moment. the battery monitor is actually working right now, but i messed up the rssi display in the process. lol! code should be up later today after i tidy up the mess i created.
-sj
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Old Aug 27, 2010, 03:15 PM
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code is up! (see first post)

i got the battery monitor mostly working! its a little screwy at 0v.... i haven't figured that out yet. i used 47k & 100k resistors to make a voltage divider. i also used a 0.5k trimmer for fine tuning. the tuning can be adjusted in the software or with a trimmer if you like. just make sure the voltage to the pin (A1) is below 5v!
enjoy!
-sj
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Old Aug 27, 2010, 04:46 PM
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United States, CA, Santa Clara
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Hey Sonic!

I posted this up in the DIY diversity the other day. I'm working on almost exactly the same idea!

Maybe we should start community project for a arduino RSSI meter / diversity switch / current sensor device.

http://www.rcgroups.com/forums/attac...mentid=3422352

I built out my hardware and have it switching video sources and reading RSSI but life got in the way and I have not worked on the code for a while.

http://www.rcgroups.com/forums/showp...&postcount=263

I ordered a few of these the other day to sense the amp draw

http://search.digikey.com/scripts/Dk...me=620-1320-ND
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Old Aug 27, 2010, 07:58 PM
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interesting... how are the switches performing for you? have you taken a look at some of the dip video swichers digikey has to offer? i found a couple of broadcast quality ics for like $5ea.

i wasn't planning on monitoring current consumption as i felt that pack voltage is a good enough indicator of battery status. 2 resistors & a trimmer is all thats needed. still interested to see how those sensors work out though...

i have a serial lcd here. they're nice, but pricey! i prefer the $0.75 shift register solution vs the $30 serial display.
cheers!
-sj
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Old Aug 27, 2010, 08:21 PM
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The switches work great on my bench! Really though I have not field tested my setup yet. The only downside to them so far is that they don't come in DIP but for the price $0.30 each I can't complain. Two of them will handle 4 video inputs for less than a $1.00

I really need to get a handle on using the shift register for LCD, I do like using this serial lcd at first just to get things running but its soooo expensive its not viable for long term install really.

The reason for the amp sensor is that I am going to use them for different project so I bought a few.

Good Stuff!

Charile
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Old Aug 27, 2010, 08:39 PM
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i have a small mountain of ic's i need to sort through! i probably have something that will switch video in there! i found 7 of the shift registers needed for the lcd so far!

heres the link to using the 74LS164 with a parallel lcd: http://code.google.com/p/arduinoshiftreglcd/ i've used both the 3 wires and 2 wire examples successfully. the 2 wire is the way to go imo.

my serial lcd is actually dead at the moment.... i always forget to unplug it before uploading a sketch! its semi-permanently confused. gotta get a icsp programmer to resurrect it.
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Old Aug 28, 2010, 01:23 PM
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How about audio feedback?

This seems fairly straightforward:

http://code.google.com/p/rogue-code/...s/Requirements

and could provide various warning levels since it is hard to always look at the bar on the lcd when flying fpv (but the lcd is very cool and a must to build anyway).
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Old Aug 29, 2010, 10:45 PM
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Why use a IC for the video switch? Is there a reason why the arduino shouldn't control a relay for the video switch?
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Old Aug 30, 2010, 05:39 PM
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here's a pic with the battery monitor active.
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