Super Simple OSD Mods (4s + RSSI)

[fransbr]

I use a EZuhf-Immersion system for the control of my model.
The RSSI of my EZuhf receiver is a digital signal, and must first be converted into an analog voltage.
For this I use adigital -> analog converter of Microtronics.
The analog signal is fed to the second port of the modified super-simple OSD.

Now I can read the RSSI numbers on my Ezuhf, It works very well.
A GPS is not really necessarily in an environment you know well, sufficientbattery voltage, time, and now also RSSI value are important data.
With this setup I have a safe and 'cheap' UHF connection for the longer distances.

See the Video and read how I did it.
http://fpvlab.com/forums/showthread....ll=1#post92629

[Hmfpa]

Hi, is this modification needed also for E-OSD? If so, how to modify it for better resolution?
Thanks!

I don't have the E-OSD, but I imagine that a similar mod could be done to improve resolution, but you would need to find the resistor since the board layout is different

[MASHTON1138]

Has any one tried to run RSSI off of a Futaba FHSS rx on this? Its probably digital knowing my luck but figured someone might know.

[chanyote66]

Has anyone thought of calibrating the second batt to an ammeter? that might be useful as well! (I have RSSI on my FRSky)

[Scotttu]

I have one of these that I bou ght but never used - not trying to steal the thread but if one of you guys wants one to play with...send a PM.

Ingenious, I love creating voltage dividers, never thought to take one out...

[chanyote66]

My SSOSD never shows text, it only has a blinking red light??? Is there any way to fix this?

[Hmfpa]

IIRC, this happens when it can't find a signal. What camera did you use?

[chanyote66]

The camera is a Chinese special, I took it off of a $25 Camera/Transmitter/Receiver combo off ebay. I have a 480tvl camera comming in from foxtech soon.

[Danub]

Has anyone experienced video jumping like this:

View this video on YouTube
I can't replicate on the ground yet. . . . It doesn't seem to be a loose connection as jiggling all wiring and connections does nothing.
Maybe it is just multipathing from the shopping center?? I dunno?

[Jack2010]

Onto RSSI mods...

EDIT: I just tested this mod with my DragonLink. Works great.

The BAT2 port (not isolated) on the OSD has a voltage range from 0.3v to 17v. Internally, there is a voltage divider (with values 4.7k and 1k) that steps this down so the 3.3v micro can read it. This is nice if you want the voltage of a second battery, but the the Corona receiver has an RSSI range from around 0.7v to 1.4v. This means that you only get two steps of resolution over your entire RSSI range.

Attachment 5714

By removing the 1k resistor, and therefore disabling the voltage divider, the range decreases from 0-17v to 0-3v, with the tradeoff of much greater accuracy. This fits the Corona RSSI voltage range better. However the OSD will still inflate the voltages, so 1v of input will read a lot higher (~6v) on the OSD

On the PCB, the resistor you need to remove is in red. I recommend desoldering it by putting a solder blob on one of the pins, and then heating the solder blob until both sides melt, then just pushing it off

Attachment 5715

If I would like to measure the ground station VRX RSSI - what replacement resistor should I put there in order the get the measurement range of 0-6V?