processors on tomtom GPS

[rookie1010]

Hello

I was looking at tht tomtom range of GPS devices

tomtom300

tomtom500

tomtom700

their specs state that the tomtom300 has a 200 MHz ARM920T
tomtom500 has a 400 MHz ARM920T
tomtom700 has a 400 MHz ARM920T

doesn't this mean that they all have the same processor, but the surrounding hardware is used to multiply the clock(perhaps a 10 MHz XO) 20(?) times or 40(?0 times, correct?

 

[PottedMeat]

There may be variations on the ARMs - there should be more letters/numbers after the name. Guessing that the Tomtom300 is low end and the 700 is high, maybe the 300 uses a lower speed grade to save costs. The processor though probably has a internal PLL to multiply the external clock.

 

[rookie1010]

thanks for the reply

what do you mean by lower speed grade?

i remember a bit about ARM processors, i think i came across 946TDMI, the T stands for thumb, i think the ARM9 series was running at 200 MHz with difficulty, we were running them at 140 MHz,

can you shed light on this 400 MHz variety of the ARM9 family?

 

[Future Shock]

Can't say for sure about the ARM part numbers, but it is quiet possible that they are all the same CPU, but underclocked in the TomTom 300. This isn't as bad as it sounds, however - the 300 would then have a bit longer battery life when used without the car kit. And the 300 probably doesn't need as fast a CPU as the 500/700, as those two have additional telecomm functions (such as functioning as a Bluetooth speaker system) that are lacking on the 300....

Future Shock

 

[rookie1010]

thanks for the reply

yeah the ARM's variation speed would cause increase/decrease in power consumption. dont know how much juice would doubling of the clock take up, though? i think it is the color screen display which would take up most of the power, correct?

i think bluetooth is a low power protocol, so though additional power would be taken up by bluetooth, it wont be considerable, correct?