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USB Power LPC2368

Started by Ad Goudsmit June 26, 2008
Dear all,

I'm working with the LPC2368 which some of you know allready.
I've implemented the link between the USB and the SD-card but now i'm having some new problems.

The device needs to be charged throut the USB cable so a special adapter and a USB-cable is provided.
But when the adapter is connected to the USB-connection, i get an USB interrupt on the device but no PC is connected.

How can i ignore this USB event??

Thanks,

Ad Goudsmit


An Engineer's Guide to the LPC2100 Series

A USB device should, after being powered through the USB, enable pull-up resistor on one data line. The host detects this pull-up and begins enumeration.
In your case, you should still enable the resistor, since you don't know if a PC is connected. There will just be no enumeration. No communication will occur over USB.

Thanks for the replays.

I managed to make it work.

Thanks again.

Ad
----- Original Message ----
From: t_chinzei
To: Ad Goudsmit
Sent: Friday, June 27, 2008 7:02:10 PM
Subject: Re: USB Power LPC2368

> But when the adapter is connected to the USB-connection, i get an
USB interrupt on the device but no PC is connected.

You may see suspend interrupt from the USB engine, when your device
connects to the charger.

It is desirable to know which connection is made, PC or the charger,
just after the connection, before initializing the USB engine.

Pull up the USB D+ line with an extra resistor, 150k or so, in
addition to the regular 1.5k pull-up resistor. Just after power up,
just this 150k resister is connected. The regular pull-up is enabled
by the firmware, as Glazar suggested.

When PC or hub connects to the device, they pull down the D+ line on
the other end with 15k (+/-5%) resistor. Then, the D+ line goes to
about 0.3V.
On the other hand, the charger has no connection to the D+ line. The
D+ line holds VDD. This voltage difference is detected by the D+ port
of the MCU as GPIO.

When you see '1' on the GPIO (D+) port, don't initialize the USB engine.

Tsuneo


Hello!

Somebody has some routine (writting or reading) for I2C EPROOM with LPC2138?

Laura
To: t...@yahoo.com; l...From: a...@yahoo.comDate: Sun, 29 Jun 2008 23:49:00 -0700Subject: [lpc2000] Re: USB Power LPC2368

Thanks for the replays.I managed to make it work.Thanks again.Ad----- Original Message ----From: t_chinzei To: Ad Goudsmit Sent: Friday, June 27, 2008 7:02:10 PMSubject: Re: USB Power LPC2368> But when the adapter is connected to the USB-connection, i get anUSB interrupt on the device but no PC is connected.You may see suspend interrupt from the USB engine, when your deviceconnects to the charger.It is desirable to know which connection is made, PC or the charger,just after the connection, before initializing the USB engine.Pull up the USB D+ line with an extra resistor, 150k or so, inaddition to the regular 1.5k pull-up resistor. Just after power up,just this 150k resister is connected. The regular pull-up is enabledby the firmware, as Glazar suggested.When PC or hub connects to the device, they pull down the D+ line onthe other end with 15k (+/-5%) resistor. Then, the D+ line goes toabout 0.3V.On the other hand, the charger has no connection to the D+ line. TheD+ line holds VDD. This voltage difference is detected by the D+ portof the MCU as GPIO.When you see '1' on the GPIO (D+) port, don't initialize the USB engine.Tsuneo

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