Add support to use the TomTom TMC reciver

[jkoan]

After navit-gps/navit#672 has been merged is would be grate it TomTom could be one of the first embedded device which would provide a real integration of it. To support this we need to find out how do address and use the reciver.

https://web.archive.org/web/20120807061302/http://www.opentom.org/TMC

[mvglasow]

Do you have any information on the receiver hardware used?

The GNS is quite widespread and RDS Surveyor/Qz are capable of addressing it. Some folks have started decoding the protocol; I’ve gathered all I could find (and discover myself) at https://github.com/mvglasow/RdsSurveyor/wiki/GNS-Protocol.

There is also a receiver by Royaltek, which transmits RDS data in NMEA sentences, I once came across some information about that one as well.

[mvglasow]

Looking around a bit, it seems TomTom has its own receivers, not any of the standard (GNS/RoyalTek) ones, and they are very likely to speak a proprietary protocol. Though that may depend on the device type as well.

From my experience with GNS (for a Falk and a Navigon device):

• Devices which come with USB connectors do not necessarily speak USB. For example, the GNS which came with the Navigon has a UART interface with a micro-USB plug.
• The devices transmit the entire RDS data stream (which means they could also pick up other RDS information), no decoding/transformation is done inside the device. The same is allegedly true for the RoyalTek, and there’s a good chance TomTom does it the same way.

If you have any way of capturing data between the original TomTom software and the receiver, that would be a good starting point…