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Old Aug 28, 2012, 07:58 PM
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Originally Posted by PMB-NZ View Post
My latest project..

I had quite a few ATmega328 chips so decided to make a Arduino Compatible board for RC and other projects. It includes 8-channel servo driver, OSD components and 3.3V regulator for the GPS. The idea is it could do stability control or OSD, but not both unfortunately.

So far I've assembled a prototype and have the Arduino bootloader running. There are a few little bits to tidy up and I'll get a batch of pcbs made.

I was thinking of making it about 15mm longer and and adding a pattern for a Ublox GPS module with off-board antenna.; but haven't decided yet.

Paul
It's really great!
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Old Aug 30, 2012, 06:04 AM
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Joined Jul 2011
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Hi everyone,

I have a problem with this osd.

I've tried several circuits and versions, but everytime I get the same result: just a normal picture without anything from osd on it.
Where am I doing it wrong ?

There's a picture on breadboard.

I'm using this circuit here: http://static.rcgroups.net/forums/at...chematic_1.png
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Old Aug 30, 2012, 09:56 AM
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Ok, nvm. now it works perfectly.

Problem was in R5 pot which didn't want to fully unscrew.

Finally I can "play" with the code a bit
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Old Aug 30, 2012, 11:31 AM
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Sweden
Joined Mar 2005
287 Posts
Now i have finally got my OSD board and im just about to solder it but i have two questions i need to get confirm:

1. The dividing resistors for battery voltage: as i got it they need to be at values so that the battery voltage at its max generate a voltage of 5V on the cpu pin to get the right readings on the OSD. Would 3k and 9k for a 3S-battery work? At full 12.6V these will create 4.2V to the cpu and this isnt 5V so it wont be that accurate i guess or what ever would happen but will it show the accurate voltage on the OSD never the less in some way?

2. The 120 and 100 ohm resistors at the video output: is there any reason these need to be changed in anyway to improve the letters or something or are these values just fine as is? I use the LM1881.


Edit: Found the answers myself after some time and also found a schematic with the 3k and 9k values in it which i then assume would work just fine.
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Last edited by Henry.; Aug 31, 2012 at 12:29 PM.
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Old Sep 08, 2012, 08:12 PM
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Ann Arbor, MI
Joined Dec 2010
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Racking my brain and could use some help....

I am getting .2 v and the current is completely wrong. I set up a bunch of resistors in parallel to simulate 1A. It showed .3 or something like that. My voltmeter was showing 1v from the current sensor (flytron 100A) which is right, but the OSD hates me.

I tried a couple of motors and they arn't showing the right voltage/amps either.

I have everything hooked up ok, checked 10 times!!! The current sensor, sensor wire, goes to A2 which I think is right if I am using default v18 code.

Please help, I am going nutz!
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Old Sep 09, 2012, 10:07 AM
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So I was a little tipsy last night and didn't explain myself very well.

I think I may have figured it out. You must have the voltage divider connected to get the VLT, even if you are using a current sensor. (shouldn't you be able to just use the RAW pin and get the voltage from there? Is there anyway to code that, save on resistors . I used a 8k on the positive, and 774 (800 and 25 in parallel) on the negative to get it exact. So the voltage is reading correct. I am still not getting the correct amps though, Going to work on that now. I am curious why we cannot use the raw pin though.
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Old Sep 09, 2012, 03:58 PM
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Have finally finished my OSD board which i designed to be able to solder directly to a PA6B GPS for simplicity and to save a lot of weight. The board have the normal video, RSSI input, battery input and one for current sensor. As soon as i have time over so will i try it out as well but im swamped right no so it could take a while though.
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Old Sep 09, 2012, 05:11 PM
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Simply a piece of art
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Old Sep 09, 2012, 10:39 PM
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Quote:
Originally Posted by Henry. View Post
Have finally finished my OSD board which i designed to be able to solder directly to a PA6B GPS for simplicity and to save a lot of weight. The board have the normal video, RSSI input, battery input and one for current sensor. As soon as i have time over so will i try it out as well but im swamped right no so it could take a while though.
Henry,
Great job! Would you mind sharing the Eagle board and schematic?
-Thank
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Old Sep 10, 2012, 01:35 AM
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Henry,
Great job! Would you mind sharing the Eagle board and schematic?
-Thank
+1, do you have any extra boards available btw
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Old Sep 10, 2012, 01:12 PM
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Thanks guys!

It was a pure hell to route it and the layout took a very long time due to it small size so i might not be that keen to share to much of it all and i hope you all could understand this.

The schematic however is no secret as its the same from Dennis Frie with the LM1881, as this use, which seem to be the one schematic that was among the most complete and accurate and i also used the one in the PA6B datasheet to get it all right.


I have 2 bare boards left and one soldered but it was only really planned to made this board for my self and it hasnt been tested or anything to see if the design work as i planned and so on. But maybe i could sell these board if they are ok since i might not that happy to just give them away for free if there might be interest, it has been to much work for that.

The GPS cant really be soldered straight on as is because some of the bottom pads have to be isolated before since the fab couldnt do covered isolated vias and these pads cant be connected to the gps but i had to do so to be able to route the board at all. And even if i now have soldered this with solder iron so is this board far from made to beginners since its SMD and mainly 0402 components and its very small distances here and there.

There is also some things that i dont know if it work that i have to test. One example is the ISP Reset (ISP main pins are the 4 vias down to the left) that is connected straight to the Reset pin on the cpu and i dont know if this would work fine like that. I have read somewhere that the Reset pin is internally pulled up in the cpu and thus prevent the use of a external resistor but have seen many schematics that use a pull-up resistor anyway but not a single extra component would fit on this board so i could only hope its ok without.
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Old Sep 10, 2012, 02:43 PM
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Illinois, USA
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damn that is small. Must be a brain surgeon.
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Old Sep 16, 2012, 06:45 PM
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USA, AZ, Chandler
Joined Oct 2004
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I got my OSD up and running on a breadboard and it seems to be working correctly, other than I haven't tested the mAh counter for accuracy. One issue I ran into was that after fixing the "VIDEO_SYSTEM" capitalization, I was only getting the lower numbers on the OSD to display. I had to set the line numbers for the upper part of the display to PAL values but the lower part of the display to NTSC values to make it look right and have everything visible. Supposedly my camera (PZ0420) is NTSC.
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Old Sep 17, 2012, 10:36 AM
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Can someone pleaseee tell me what pin to hook the current sensor up to?

Thanks-
Mike
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Old Sep 17, 2012, 10:59 AM
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Quote:
Originally Posted by mklinker View Post
Can someone pleaseee tell me what pin to hook the current sensor up to?
I believe the default pin is A2. If you are using version 18, check your config.h file and see what value is set:

Code:
#define current_sensor_input 2
You can change the pin by changing the number, just make sure nothing else is using it. The current sensor, voltage divider, and rssi inputs all use analog pins, the others are digitals.
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