Rikaline GPS with TomTom carkit - anyone any ideas?

BrowningC · Occasional Visitor Joined: Apr 06, 2004 Posts: 26

Following a purchase which I must confess was based on inadequate research, I bought a 2210/Rikaline GPS receiver combination, then realised I wanted the neatness of the TomTom carkit pod. The pod requires a US-phone type plug to connect to the pod (ie the plug which is supplies on the genuine TomTom GPS receiver) and the Rikaline comes with a PS-2 type plug.

I asked Rikaline for help but their only response was 'You cannot get an adapter'.

Has anyone found a work-around for this?

DavidW · Posted: Thu Apr 22, 2004 1:12 pm Post subject:

Possibly the easiest way out of this is to use the Brodit mount that reproduces the iPAQ's connector on the bottom of the mount. You can get very neat results using this approach without having to mess around rewiring your GPS (which, if you get it wrong, could destroy the GPS).

David

siwatkins · Occasional Visitor Joined: Dec 07, 2003 Posts: 32

BrowningC · Occasional Visitor Joined: Apr 06, 2004 Posts: 26

Sorry for answering my own post, but thought I would report this in case anyone else is in the same boat...

Eventually, out of frustration, I made my own adapter....

The Rikaline comes with a mini-DIN or PS/2 type plug, and the TomTom requires a telephone-type plug (in the UK it is the plug that goes into the phone itself not the one that goes into the wall). Probably the easiest way to get these plugs is to cut the PS/2 one off an old mouse and to cut the phone one off an old phone, though in fact I was able to acquire a PS/2 one from my local electronics knick-knack shop.

Then I did some simple wiring investigation - (multimeter essential). Four wires run between the IPAQ/TomTom plug or pod (and hence the IPAQ when it is plugged in) and the GPS receiver. Two of these supply the power, and two transmit the data. With the original Rikaline set-up, the voltage is stabilised in the car adapter plug and runs in both leads - one from the car adapter plug to the IPAQ and the other from the car adapter to the Rikaline. In the TomTom set-up, the car adapter is just a passive plug and the voltage reduction is done in the TomTom pod - both for the IPAQ and for the GPS.

Using the original cable which came with Rikaline (and with the IPAQ well out of the way) I identified which pins carry the supply (it is 5.1 V), paying particular attention to polarity. I then powered up the TomTom pod and identified the two wires there which carried the supply (again without the IPAQ anywhere around), and again with attention to polarity. I then soldered the wires in appropriately. This left me with a second pair - the data wires - which I just soldered together, polarity being irrelevant here. You may need to open the PS/2 plug on the original Rikaline set-up to work out which four of the six possible pins are actually used.

Slightly to my surprise, when I had worked all this out I had got it right and my IPAQ now works happily from its TomTom pod with the Rikaline GPS receiver.

Anyone trying this must remember it is the polarity of the power supply and getting it onto the correct pins which is crucial - the rest will follow, but if you get that bit wrong then damage to the electronics is highly likely.

DavidW · Posted: Sat May 01, 2004 1:31 pm Post subject:

That's a good description of how to do it. If you get the serial polarity wrong, there is a potential risk if signal ground and serial ground are tied together at both ends - if not, it simply doesn't work.

There may be a fifth wire somewhere - which is transmit data to the GPS (SiRF based GPSes can be configured using the serial port). It is worth hooking this up - not least so that the "Centre GPS on this location" functionality works if you lose your position lock.

The PS/2 plug is a standard 6 pin mini DIN plug, which should be available from electronics suppliers.

David

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