LPC1756 USB Communication works only during programming every time in VECTRESET mode

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LPC1756 USB Communication works only during programming every time in VECTRESET mode

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by sathyan on Wed Apr 23 03:27:23 MST 2014
Hello!

I have brought LPC1756 Chips and made a custom board for it.

I tried to program the chip using the LPC1768 sample codes.

I am able to get the output for basic GPIO, UART Programs. But, when i tried communicating with USB Mass Storage, I am getting a weird problem.

After flashing the code using CoFlash tool configured in VECTRESET, i am able to send and recieve data through the usb of LPC1756. but when i reset the chip, i am unable to communicate with the USB! the program halts at Write Done Back Head Interrupt! But still on every reset i am able to get the outputs from UART and other GPIO but not from the USB!

Then i tried configuring the CoFlash tool in VECTRESET and clicked on blank check, then i am able to send and recieve data through USB!

But i cannot do this every time for a standalone device.

Please help me why am i not able to communicate through USB when the configuration is in SYSRESETREQ/HWRESET?

Why am i getting output only once for every program/blank check while the configuration is in VECTRESET?

Why does the reset button works only for the UART/GPIO and not the USB?

It seems like the memory map is simillar to both LPC1756 and LPC1768 for the UART and USB. Where am i making mistake?

please help!

Regards,
Sathyan
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