Flashing your G-OSD with CL-OSD

by lobstermash | August 16, 2012 | (8) Posted in Projects

Another UPDATE: Well, Hobbyking have been installing open source firmware on their gadgets out of the box lately. The G-OSD has finally gone the same way. I guess this article is still relevant if you get an old one, but if you want to go pre-flashed, here it is: G-OSD 3


UPDATE: Wow, it pays to review an article every now and then... I still use my G-OSD for FPV, as it's a great value little unit. There are also a number of other GPS units that you can plug in and program to better refresh rates. 

One important update to this article is that Hobbyking have brought out the latest version of the G-OSD: it's cheaper and supposedly a little better, though I can't tell the difference besides the price TBH. 

My first few FPV flights were very basic and simple - cheap 200mW system, stock antennas, no OSD, all kept pretty close to base.

Yeah, it seems like only a couple of weeks ago... Hang on, it was! I'm a newbie FPVer, and proud of it. So what can a newbie teach you that you can't learn from RCG, or Bruce from RCMR, or Dave W? The answer is how to from a newbie perspective. 

After my first couple of flights, I knew I needed three things to keep it interesting and make it safer. 1. Power consumption (I ran one battery flat, thankfully close to home, and had a friend bring it in for me); 2. an arrow pointing toward me (I got horrendously lost flying from a hill, as I couldn't find myself anywhere) and 3. better antennas.

Antennas are pretty well covered by, well, lots of people. I liked Bruce's method, keeping the shielding intact rather than bunching it in 3 or 4 strands (personal preference). I made up a set of cp antennas for my 900Mhz system and the reception is rock solid.

For needs 1 and 2, I needed an OSD. I'm on a very tight budget and wanted the cheapest, effective thing with a home arrow. I noticed HK had the G-OSD, but was amazed that it didn't have this feature!!! What's more, it had plenty of other faults! But then I spotted some magic words hidden in a review... 'open source'. 

I recently reflashed my Turnigy 9x and wonder how I put it off for so long. I still have my AVR programmer, I've got my mad soldering skills, why not turn a froggy $40 OSD into a princely instrument set!?!

For those that have done the 9x, beware.  The instructions have been revised many times and it's pretty darn simple to do. CL-OSD, while wonderful (all props to Callelj and other who wrote/refined this), is not so easy and the instructions are hard to follow for a non-programmer like me. WinAVR might as well be Japanese to me. Even for soldering the programmer on, the pads are really close together! 

Unfortunately I can't help you much with the soldering bit - just be careful and quick, while also taking your time. A sharp soldering iron tip is essential. Remove the heat shrink to reveal the pads. For cable to pad layout: 


Wire 1 (MOSI, the red one) connects to the left-most pad (let's call it 1).

Wire 9 (MISO) connects to pad 2
Wire 7 (SCK) connects to pad 3
Wire 5 (RST) connects to pad 4
Wire 10 (GND) connects to pad 5

Wire 2 (VTG) connects to pad 6

Once your soldering is done, plug the programmer into your USB. If you haven't installed the drivers, here's where they are: AVR drivers. I had trouble getting the drivers to work. I installed them eventually by opening up 'Devices and Printers' and right clicking on the icon for the programmer to go into 'properties'. Then click on the 'hardware' tab and select properties again. Click on the 'driver' tab and then select 'update driver'. Select the driver folder from your computer (where you unzipped it) and hey presto... If it doesn't work, try permutations of this until it does. 

Anyhow, once your programmer is working, I found the most simple program to flash the firmware with is eXtreme Burner AVR. Once you've downloaded this, you'll need to download the eeprom and hex files for CL-OSD. Right click the links and 'save link as...'. 

Insert your AVR programmer if you haven't done so already, and open eXtreme burner. Click on the 'chip' menu and select 'ATmega88'. Click on 'file' and select 'open eeprom file'. Select cl-osd.eep and click ok. Then, click on file again and select 'open flash' and choose the cl-osd.hex and click ok. Then click on 'write all' and it will write both the eep and hex files onto your G-OSD!

If you've only written the hex file on there, you'll get white blocks where the letters and numbers should be, as the alphanumerics are defined in the eeprom programming. 

Also, if your LED no longer works when you power up, don't panic. It'd not dead until you see smoke! Just try and reflash it again. When the programming makes sense, the light comes on. 

I'll let you figure out how to wire the OSD up, but here is what the display should look like in the end: 

Once again, props to Callelj for writing this piece of genius firmware, and to those who refined it. 

Remember that this is a $40 OSD. There are still plenty of little tweaks that people have been making to the programming. People have still reported the need for GPS coordinate and altitude calibration, which I have no clue how to do and is apparently case-by-case different. The folks at RCG are pretty helpful though, and there's 111 pages on this mod to sift through for tech support if you're scared to ask questions. 




ycopter on August 16, 2012
Really useful article, thanks for posting. I have already flashed one G-OSD but that was some time ago and I have another one waiting to flash. This article will be a useful reference.
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lobstermash on August 16, 2012
My pleasure. I literally had just finished successfully flashing mine yesterday and thought I'd better write it down before I forgot!
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lefty on November 18, 2014
please look up the meaning of the word literally
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lobstermash on November 18, 2014
Three things,lefty...
1. Please look up 'gift horse', but please avoid looking it in the mouth.
2. Just because you just finished listening to Weird Al's 'Word Crimes' does not make you a literary genius. The informal use of the word 'literally' for emphasis is acceptable in the vernacular in the context I used it.
3. Have you heard of the convention of using a capital for the first word of a sentence and finishing it with a full stop? Seriously, go and troll someone on Twitter or something...
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subsonichobby on September 1, 2012

try this.


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subsonichobby on August 24, 2012
Try this http://subsonichobby.blogspot.com/2012/08/g-osd-converted-to-cl-osd.html

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lobstermash on August 24, 2012
I saw that this morning. Nice job.
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Superfly on August 16, 2012
Useful article with references. Thanks!
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lobstermash on August 16, 2012
Sorry there aren't many pics. I was thinking of doing screenshots... But we'll see how people go. I don't want to spoonfeed too much!
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lobstermash on August 18, 2012
I'm not sticking my nose up at 4 stars, but what do people want to see in this article? Anyone tried to flash a G-OSD using these instructions? Happy to oblige and help further where I can...
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anansi22 on May 21, 2014
I used these instructions today to flash the g-osd. There are a few deficiencies in the article. The files as downloaded from google are configured for PAL video. Flashing using your instructions and running NTSC results in just the circle in the upper right corner, no other OSD info visible. I searched google and found a prebuilt package with the NTSC eeprom and hex files. Those worked flawlessly.

Another issue I ran into is the chip on the OSD was the atmega 88P, not the 88. This resulted in a mismatch error on verifying after flashing. This can be ignored as the flash was successful, the signature on the 88 differs slightly from the 88P, otherwise they are identical it seems.

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BodhiDogma on April 24, 2014
I recently spent quite a bit of time rebuilding the cl-osd software and generally exploring the potential before finally stumbling upon a full re-write as u-osd by Alex here (http://www.rcgroups.com/forums/showthread.php?t=2123788)

If you run a windows machine, it even includes a configuration tool to update any settings / tweaks and uploads to the eeprom so you don't need to rebuild for every variation / layout adjustment.

Very nice!
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Flashing your G-OSD with CL-OSD