Thanks for your notes Erik. I am doing the project to wirelessly transmit MEMS ADIS16488 sensor's data though the Xbee Pro S1 module. I once successfully captured raw data from the sensors and put it on the X-CTU(http://www.digi.com/products/wireless-wired-embedded-solutions/zigbee-rf-modules/xctu) terminal using the LPC11u24 Microcontroller.

I used the xbee_lib to simplify the code(http://mbed.org/cookbook/Xbee-Pro)

At the other end, I used the Xbee explorer from the sparkfun :https://www.sparkfun.com/products/8687

I did make the whole setup work before switching to the LPC1768! I simply collected the raw data and sent to the XBP serial input. The terminal of the xctu did show the data. But now suddenly it does not work.

The LPC11u24 only has one physical UART (Serial) for example, so if you also send data to your PC it cannot use an UART for the xbee (they use uart, right?).

It looks like the official schematic shows only 1 UART serial port, I am wondering what are pin 13 and 14 for?(Just for curious) Actually I only used 1 serial of 11u24. The case here is that 11u24 is collecting raw data from MEMS sensors though SPI protocol, and then it would send them to the DIN of the Xbee Pro, which is an UART, right. Next the Xbee Pro would transmit data wirelessly to another Xbee Pro(receiver) and then the receiver output data on the terminal(X-CTU), on which there are some mistakes.

The mistake here is that the Xbee transimtter would stop transmission at the point where the data value is 0. Moreover, the X-CTU terminal would show only dots while the Hex number of them were all correct(same with what I transmitted).

Both the USBTX/USBRX and p13/p14 pins can be UART, but not both at the same time.

But without knowing your program, and probably hardware I don't have, this is hard to figure out. That it shows different stuff in the terminal while the same data is in it sounds more like a software issue on the pc. Or maybe it is something else. But you might try to start with a basic program and find out where it is going wrong.

Thanks, I did not know that. It is possible to use both SPI ports right?Because I want to get data from sensors while store data into a micro SD card. It is so weird that I can't believe. It used to work well for the 11u24. And all transmitted data were correctly shown on the terminal, but all have changed after switching to 1768..

You might be thinking why I changed to 1768..because the 11u24 seemed to be broken and it did not work anymore. All I have right now at my hand is 1768. Here comes my another question, I used 9V battery to supply Vi pin during the test and the 11u24 functioned well. The next day I came to lab, it's dead..When I powered it up again, the upper left component (it seems like a regulator) is very heat. It would not response(LED's not light) even if it's powered by the USB cable either.

Thank you Ceri. Please refer to the comments to Erik. Also, The situation right now is: it turned out that the Xbee transimtter would stop transmission at the point where the data value is 0. Moreover, the X-CTU terminal would show only dots while the Hex number of them were all correct(same with what I transmitted).

Thanks Robin