Re: [Paparazzi-devel] RSSI message with Xtend modem

[Stephen Dwyer]

Hi Michal,

A while back I implemented reading the RSSI pwm output on the XTends for LPC21xx. Worked fairly well, but rather simple and not very friendly to a more standardized datalink rssi. This was airborne side only of course, since we could clearly see rssi on the ground side with the standard development carrier board. See message name XTEND_RSSI in messages.xml, as well as the module in sw/airborne/modules/datalink/xtend_rssi.[c|h] and conf/modules/xtend_rssi.xml.

Just some thoughts for a non-AT cmd based solution.

A better option might be to use API mode. This should be really similar to the XBee API mode, if not the same, so probably wouldn't require much work there. You can probably then implement RSSI more easily, as well as perhaps some other diagnostics. This should be applicable for both the air and ground side.

Thanks,

-Stephen Dwyer

On Thu, Oct 31, 2013 at 1:57 PM, Michal Podhradsky <address@hidden> wrote:

Hello all,

I would like to read the received Signal Strength Indicator for telemetry datalink. I am using Xtend Modem (http://www.digi.com/products/wireless-modems-peripherals/wireless-range-extenders-peripherals/xtend).

There is a set of AT commands for the modem, one of them makes the modem to return the RSSI value.

What would be the best way to seamlessly implement this functionality into paparazzi? Assume I would like to read the RSSI both on the ariplane and the GCS modem.

One (probably the best?) option is to add another message, and edit the messages.xml parser so the function DOWNLINK_SEND_RSSI does contain the right AT header (instead of the transparent header). I am just not sure which ocaml files to edit.

Another option would be to sneak in your own message (uart_transmit ... ) and then wait for the response (the disadvantage is that you might lost some telemetry commands).

Thanks for your comments!
Michal

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