DragonOSD+ board connections

Support related stuff, for various products
Daniel Wee
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Joined: Wed 25 Feb 25 2009 8:00 pm

Re: DragonOSD+ board connections

Post by Daniel Wee »

RSSI Input

The RSSI input is also shared with the analog temperature sensor. Note however, that when used as an RSSI input, you ONLY USE THE FIRST AND THIRD PINS of the header. DO NOT CONNECT ANYTHING TO THE MIDDLE PIN. The middle pin carries 3.3V and is meant to power the analog temperature sensor and should not be connected to any other power source.

Note that most receivers were not meant to have their RSSI line tapped for external use. Internally, RSSI is often used as part of the AGC (automatic gain control) circuitry of the receiver. As a result, connecting the RSSI line indiscriminately could very well cause the receiver to malfunction. On some radios, you might get away with this. On the DragonLink receiver, the RSSI output is isolated from the receiver so that's no problem but for most of the other receivers, you should not assume that just because you have the RSSI line, you can just hook it up to the OSD (any OSD for that matter) and have it just work. In many cases this will not be the right thing to do.

What you need in these situations is a signal buffer to prevent overloading the RSSI line. It is quite easy to build one of these if you are familiar with electronics - just a simple unity gain DC buffer using some high impedance op-amp. If you want to buy one, you can try the DPCAV one in the following link:-

http://www.dpcav.com/xcart/product.php? ... ge=14&js=n

You can take the 5V from the receiver to power that RSSI buffer.

Daniel
Daniel Wee
Site Admin
Posts: 2449
Joined: Wed 25 Feb 25 2009 8:00 pm

Air-speed sensor

Post by Daniel Wee »

Air-speed sensor

The air-speed sensor is a very specific part, the Honeywell HSCMRNN001PG2A3. Other analog types such as available from Motorola (MPXnnnnn) won't work. Only this exact part will work. You can get the part from:-

http://sg.farnell.com/honeywell-s-c/hsc ... dp/1751290
http://gb.mouser.com/ProductDetail/Hone ... gvfw%3d%3d

The connections are very straight-forward. Just hook up the 3.3V, GND, SDA, SCL from the device to the corresponding pins on the peripheral connector on the DOSD+ board. It is recommended to add a 0.1uF (100nF) decoupling capacitor across 3.3V and GND at the device pins. An additional 1uF won't hurt either. The pinouts can be found from the attached datasheet.

Daniel
Attachments
Honeywell-HSC Series 1psi-150psi.pdf
(623.57 KiB) Downloaded 8373 times
John Lee
Posts: 105
Joined: Thu 26 Feb 26 2009 12:24 pm

Re: DragonOSD+ board connections

Post by John Lee »

Attachments
DOSD-STL-BARO_00.jpg
DOSD-STL-BARO_00.jpg (98.87 KiB) Viewed 31703 times
John Lee
Posts: 105
Joined: Thu 26 Feb 26 2009 12:24 pm

Re: DragonOSD+ board connections

Post by John Lee »

Connecting the supplied current sensor incorrectly may result in permanently damaging the MCU! DO NOT DO THIS! Make sure the black wire is facing the EDGE of the OSD!
Attachments
Do NOT DO! :(
Do NOT DO! :(
P1040273A.jpg (252.55 KiB) Viewed 31528 times
Do NOT DO! :(
Do NOT DO! :(
P1040279A.jpg (302.69 KiB) Viewed 31528 times
Correct Way To Do! :)
Correct Way To Do! :)
CS.JPG (247.94 KiB) Viewed 31528 times
John Lee
Posts: 105
Joined: Thu 26 Feb 26 2009 12:24 pm

Re: DragonOSD+ board connections

Post by John Lee »

Installing the supplied current sensor in the PWM pins may result in damaging the OSD PPM.
Attachments
Do NOT DO! :(
Do NOT DO! :(
P1040283A.jpg (238.27 KiB) Viewed 31528 times
Correct way to connect the current sensor! :)
Correct way to connect the current sensor! :)
CS.JPG (247.94 KiB) Viewed 31528 times
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