DragonOSD+ board connections

[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]

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

[John Lee]

Barometric Sensor produced by Andrej can be found here:
http://fpv-japan.com/item/barometric-al ... d/lang/en/
http://www.hobbywireless.com/cart/index ... cts_id=633

John

[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!

[John Lee]

Installing the supplied current sensor in the PWM pins may result in damaging the OSD PPM.