Mobility Site - View Single Post

bigbop · 01-06-07, 09:20 AM

Yet another interesting discovery while I'm reverse engineering the X50v drivers - As I mentioned earlier, after A02, the OHCI.DLL module was replaced with PERIPHERAL.DLL.

I was wondering what that driver did as it used the same device number as ohci.dll. Well now that I can pull apart the ROM, I grabbed the driver and had a look inside.

If you will recall a number of posts ago, I also discovered that grounding either pin 5 or 6 of the sync connector would turn on a +3v output at pin 7. This didn't work at ROM A02. Why? Because it's peripheral.dll that controls that functionality.

So, what Dell did was to replace the ohci.dll driver which didn't control any accessible USB ports with peripheral.dll which controls the power output on pin 7, through pins 5 & 6.

Also, while tracing back the pin 7 output on the PCB, I found the switching transistor that controls the output voltage. You should be able to pull a maximum of about 100mA @ 3v from pin 7 without any problems. This is enough to drive the RS232 dongle or any other device. Just make sure you put some current limiting protection in your device. Pulling more than 100mA could kill the transistor on the PCB.

01-06-07, 09:20 AM	#266 (permalink)
bigbop Aximsite Veteran Join Date: Mar 2005 Location: Toronto Posts: 1,093 Device: A1200,Moto-Q Carrier: Rogers Thanked 0 Times in 0 Posts	Purpose of peripheral.dll discovered Yet another interesting discovery while I'm reverse engineering the X50v drivers - As I mentioned earlier, after A02, the OHCI.DLL module was replaced with PERIPHERAL.DLL. I was wondering what that driver did as it used the same device number as ohci.dll. Well now that I can pull apart the ROM, I grabbed the driver and had a look inside. If you will recall a number of posts ago, I also discovered that grounding either pin 5 or 6 of the sync connector would turn on a +3v output at pin 7. This didn't work at ROM A02. Why? Because it's peripheral.dll that controls that functionality. So, what Dell did was to replace the ohci.dll driver which didn't control any accessible USB ports with peripheral.dll which controls the power output on pin 7, through pins 5 & 6. Also, while tracing back the pin 7 output on the PCB, I found the switching transistor that controls the output voltage. You should be able to pull a maximum of about 100mA @ 3v from pin 7 without any problems. This is enough to drive the RS232 dongle or any other device. Just make sure you put some current limiting protection in your device. Pulling more than 100mA could kill the transistor on the PCB.