USB device operation help

[lpcware]

Content originally posted in LPCWare by ranaya on Mon Jul 02 20:21:55 MST 2012
Hello Every1......

    I need some advice to make my usb device work. I planned to use it as a self powered device because after the configuration of the device via PC is done, it should operate as a standalone device (data logger).
   According to the getting started doc and forum threads, 5v,D-,D+ and Gnd of USB should be connected to VIN, D-, D+ and GND of the board respectively. And it works.

But to power up the lpc1769 xpresso board as a self powered device, I use a battery supply and connect it to the 2nd pin VIN of the board. And just tied D-, D+ and GND of usb cable to relevant pins. But the usb enumeration does not happen. What might be the cause ? Is it my wiring ? Or the software ? (I modified the descriptor too for selfpowered - VCOM demo project)

Thanx

[lpcware]

Content originally posted in LPCWare by ranaya on Tue Jul 03 09:45:50 MST 2012
Sry, I could solve it. I use lpc1769 xpresso board.

Battery supply means not the VBAT, it's for the external power. For a standalone device.

@Mr.Zero: I didnt separate it yet. The entire connection looks like this.
[IMG]https://dl.dropbox.com/u/16049803/untitled.JPG[/IMG]

5v pin of usb is not connected to anything, Previously I hadnt connected the usb GND to the board GND. After fix that, it enumerates in the host side.

[lpcware]

Content originally posted in LPCWare by Ex-Zero on Tue Jul 03 02:18:15 MST 2012
Which hardware are we talking about :confused:

Did you separate your LPCXpresso target board from LPC-link?

If not, did you at least separate JTAG_RESETX J4-11/12 :eek:

See also #11 of http://knowledgebase.nxp.com/showthread.php?p=17177

[lpcware]

Content originally posted in LPCWare by Tsuneo on Tue Jul 03 01:10:35 MST 2012

---

Quote:
I use a battery supply and connect it to the 2nd pin VIN of the board.

---

Do you mean VB (battery supply) pad, which sits on the next to VIN (EXT_POWX) pad?
VB pad supplies just to RTC power domain of the chip. Its power doesn't reach to MCU core and IO.

Both of power supplies are connected to VIN pad over diode switches,

                  Diode1
USB VBUS (5V) o----->|---+
                         +----o VIN (EXT_POWX) pad
      Battery o----->|---+
                  Diode2

Select Schottky diodes of low Vf.

For self-powered configuration, USB VBUS (5V) connects to P1.30 (VBUS alternate function), too, over a protection resistor (~10k).

Tsuneo