Tomtom rebooting problem tips   

Tomtom rebooting problem tips

Postby mrlongest » Sat Dec 04, 2010 4:27 pm

With regard to the tutorial with the above title, my experience tends to suggest there's another reason for my TT ONEXL rebooting after switch-off.

It depends upon the navcore and map in use (I've several SD cards with different combinations) and the actions in process (how busy the device is) at the time of switch-off.

The more active the device is at the time of switch-off the more likely a reboot.

This all is symptomatic of inadequate decoupling between the data and power lines somewhere in the electronic circuitry - i.e. a hardware design issue: crosstalk from the power to the data lines. In other words a high level of dc loading (sporadic/pulses) on some power line(s) couples across to the data line(s) just enough to cause an instruction to be sent to the processor to reboot the device.

This idea is supported by the commonly expressed solution - as the tutorial says in "tipp" 3 - connecting your Tomtom to an original Tomtom car charger can stop rebooting. A good charger with a low impedance will supplement the battery's higher impedance and reduce (soak-up) any power line pulses before they can get to to a data line and reboot the device.

Any views?
Has anybody any evidence that any work has been done (on this or another site) on TomTom's hardware to improve power line decoupling (e.g. by adding capacitors at strategic points on the circuit board)?
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Postby Downunder35m » Sun Dec 05, 2010 1:18 am

Keep in mind that these tipps are for the use of original Navcores.
There some problems when using other Navcores than the one Home wants you to use.
Generally speaking it means that if you have problems with a Navcore on your device it is best to try a different one or if no luck use the original Navcore and patch it.
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Postby mrlongest » Sun Dec 05, 2010 1:39 pm

Very good point, Downunder35m.

An "unofficial" navcore in a device couild easily increase the loading on its processor beyond its original design limts and thus result in the rebooting problems precisely for the reason I suggest in my first post.

I've found the rebooting often can be avoided if such a device is left alone for a minute or two before switching it off. For example wait for a minute or two after a journey (so the device has ceased moving) and also after entering any new instruction on the screen.

But ellaborating upon my original question; is there any other site that specifically deals with TomTom hardware questions? I've only found opentomtom.org.
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Postby tendriver » Sun Dec 05, 2010 1:41 pm

mrlongest wrote:Very good point, Downunder35m.

An "unofficial" navcore in a device couild easily increase the loading on its processor beyond its original design limts and thus result in the rebooting problems precisely for the reason I suggest in my first post.

I've found the rebooting often can be avoided if such a device is left alone for a minute or two before switching it off. For example wait for a minute or two after a journey (so the device has ceased moving) and also after entering any new instruction on the screen.

But ellaborating upon my original question; is there any other site that specifically deals with TomTom hardware questions? I've only found opentomtom.org.


Not that I am aware of.
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Postby Downunder35m » Sun Dec 05, 2010 11:41 pm

The problem is that TT only allows certified contractors to have to documentations needed.
And in most cases a defective device is sent to TT for repair/replacement.
If TT would release the hardware documention free to everyone we would not have any problems ;)
But the times were you had the schematics and ciruit layout included in your manual are long over I'm afraid...
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Postby Fatboyfun » Mon Dec 06, 2010 12:01 am

I think that if the device is suspended while a write operation is happening then files may get corrupted and the rebooting may be the software fixing the problem. That would make sense if leaving the device idle for a minute before suspending reduces the problem. This is definatly the case for random factory resets on DTV boxes and TV's. Maybe it's the same for Tomtoms.
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