Hardware USB
From OpenTom
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USB in general
Different TomTom models have different USB solutions. To our knowledge, the best way to find information about them are the various tomtomgo-io*.h files in the arch/arm/mach-s3c2410 directory in the Linux sources.
The following is partial, and compiled from that. Feel free to add:
- TomTom Go 710/910 (Valencia) has an external PLX NET NET2272 chip. The TomTom source tree doesn't include drivers for them, but drivers are available form PLX web site. However, at this writing, it is unknown whether that actually can be used, though. Hence, nothing of the below works.
- TomTom One (v6) 3rd edition (Casablanca) uses the S3C2412 internal USB. 2412 supports only FullSpeed (USB 1.1), not HighSpeed (USB 2.0). The gadget FullSpeed driver in the later TomTom kernels does not compile. The host mode USB module does compile and load, so the description below should work. However, there is some indication in the code that the OHCI (host mode) driver works by default on the second USB port, not the one connected to the OTG connector in the bottom of the device.
USB in some Go and One Models
The TomTom Go has a Mini-USB connector on its back. The CPU can operate this port either in client or host mode. TomTom's original kernel doesn't use USB at all. The bootloader allows access to the SD-Card via USB and therefore operates it in slave mode.
The problem is that an 1.5kOhm resistor pulls the D+-Line up to 3 volts inside the TomTom Go. This configuration indicates a USB client. That's why the USB port can't be used in host mode without a little trick.
How to attach a USB-Hub to TomTom Go
- get a selfpowered USB 1.1 hub. Bus powered hubs won't work as there is no power on the bus. USB 2.0 will make things veeeeeery complicated.
- open your USB hub and find the 1.5kOhm resistor which pulls the D+-Line up to 3V level and desolder it.
- cut a USB cable in two, reconnect each wire and add two 15kOhm pulldown (to ground) resistors - one for D- and one for D+. If you want to be able to force a bus reset make those resistors switchable.
- connect your hub to TomTom Go using this cable.
- boot a linux 2.6 kernel with the appropriate driver. When the driver initializes it will force a bus reset and the TomTom Go will discover your hub. If you want to attach your hub after booting you'll need to force a bus reset.
Internal USB-Pull-Up can be disabled
We now know that the internal USB pull up resistor can be disabled, which makes it possible to construct a USB-host cable where you can connect a HD without modifying a USB hub. Kernel support is already in the CVS.
How can give an introduction to use usb?
I've already construct the USB-host cable.
I own an self powered USB 1.0 HUB to.
But after connecting tomtom and hub the the lights on the hub don't lightning.
the USB cable
Connector to hub (frontview) ______ / \ | 1 2 | | 4 3 | +______+ 1 = Vcc 2 = D- 3 = D+ 4 = GND
Connector to tomtom (frontview) ___________ ( 5 4 3 2 1 ) |_________| 1 = Vcc 2 = D- 3 = D+ 4 -------- 5 = GND
hub
4 3 2 1
| | | |
| | |
| +------+ | |
O--+15kOhm|--O |
| +------+ | |
| | |
| +------+ | |
O--+15kOhm|--+--O
| +------+ | |
| | |
| | | | |
5 4 3 2 1
tomtom
Using a USB Modem with TomTom GO
The above USB cable presumably opens the door to the use of USB devices with the Tom Tom GO, provided the device has Linux drivers.
For wireless modems 3G HSDPA is the latest thing. In Australia there is significantly more coverage on the 3G HSDPA 850MHz band than there is on the largest GSM network in the country, which is probably quite unusual.
One such HSDPA modem with Linux drivers is produced by Zadako:
http://www.zadako.sk/Index.php?Category=products&Product=data&CategoryID=1&ID=78
A 3G modem linked to a TomTom GO opens a world of possibility. If somebody on this community is able to look into this more closely, I think it would be a great step forward.
The Above Does Not Work With TomTom ONE 3rd Edition
None of the above works with TomTom ONE 3rd Edition. --Ka9mva 15:59, 1 March 2008 (CET)
