Hello
I am using LPC1768 for one of the project and i need to detect if the USB device is plugged in. How is it possible that i detect something like a pen drive being inserted.
I will be using the controller to interact to the PC as well as with a pendrive and i dont intend to use OTG. I need to have a option which will be able to detect the connection type.
Regards Prakash
Hello Tsuneo
Is the D+/D- pull-down resistors (R8/R9) on the first figure are switched by NPN transistors, as you show in the second figure?
I am switching ON these two NPN transistors and trying to communicate with the pen drive.
On the device circuit, Replace NPN transistor (Q1) for the D+ pull-up with PNP. On the NPN emitter-follower circuit, V<sub>CE</sub> doesn't saturate, less than V<sub>BE</sub>. You may take this circuit from some KEIL board, but it is wrong one.
It can be seen that Q1 that is being used is already a PNP configuration.
As you rightly suggested, I have tested the HOST and the device code saparatly and everything seems to work fine.
It would be very helpful if you can post the relevent changes. probably a circuit would be very helpful.
-Prakash
>> On the device circuit, >> Replace NPN transistor (Q1) for the D+ pull-up with PNP.
> It can be seen that Q1 that is being used is already a PNP configuration.
Aha surely, It's PNP. But the emitter and the collector are swapped on the schematic.
Tsuneo
>Aha surely, It's PNP. >But the emitter and the collector are swapped on the schematic.
The schematic I have send of USB device is working fine.
I don't know why it works. It shouldn't. Maybe, the pins on your footprint of the layout is swapped?
Compare your schematic with Olimex's www.olimex.com/.../LPC-1766STK-SCH.pdf
T3 (just near USB_DEVICE label) on Olimex's corresponds to your Q1.