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From: | Chris Gough |
Subject: | Re: [Paparazzi-devel] 3dr as modem datalink |
Date: | Sat, 8 Feb 2014 00:39:45 +1100 |
The SiK firmware can be configured with AT serial commands. AT setting 6 switches on/off MavLink mode. You can ask the modem what the AT 6 setting is with the command "AT6?". It will answer 0 (transparent serial, MavLink mode OFF) or 1 (MavLink mode ON). With MavLink mode on, the modem will do 2 things differently. First, it will organise data into radio packets so there is a whole number of MavLink frames in each radio packet (no frames split across packets). This is good because it minimizes the cost of dropped packets. The result is better bandwidth and range in noisy conditions. The other thing it does is inject link quality (RSSI and other statistics) data for the modems info the data stream, which is interesting to know.
If you are not sending MavLink data, the MavLink framing is not helpful, and the Mavlink injection won't happen. I don't know if you will get a dead link like you described, I think it's undefined. You can switch the MavLink mode off with the command "ATS6=0", then persist the change with "AT&W". The command to switch it on is "ATS6=1", but don't do that. In case you are interested, see here for details on how frames are packed in MavLink mode: See here for how RSSI packets are injected: It would be possible to create a Paparazzi framing mode, but nobody's done that. I spoke to Tridge about it a while ago and he said "patches welcome". ATS6=2 anyone? Chris Gough
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