Unreliable communication using LPC2129

Hi,

I have just finished populating a custom board running an LPC2129 from NXP.

I noticed the LPC2129 is unreliable. I can read its ID using the NXP utility and Flash Magic, however once I’ve done that I cannot read or erase the device…

I also noticed the JTAG interface is unreliable. I have reused the schematic from Olimex to interface with the JTAG. Flashing and debugging with the JTAG (openOCD JTAG from Olimex) sometimes works but often fails to verify the program it just burnt in flash. I have increased the JTAG clock divider but this does not solve the issue.

I read on the net (www.olimex.com/dev/pdf/lpc-h2129.pdf) that the LPC2129 is not reliable with an oscillator higher than 10Mhz. I have a 12Mhz quartz with 18pF capacitors, which seems like a typical setup, and I am wondering if this is why I am having issues with this processor…

Any idea of what is happening?

I have not had such issues with the LPC2148… Any difference between the 2?

jeanseb:
Hi,

I have just finished populating a custom board running an LPC2129 from NXP.

I noticed the LPC2129 is unreliable. I can read its ID using the NXP utility and Flash Magic, however once I’ve done that I cannot read or erase the device…

I also noticed the JTAG interface is unreliable. I have reused the schematic from Olimex to interface with the JTAG. Flashing and debugging with the JTAG (openOCD JTAG from Olimex) sometimes works but often fails to verify the program it just burnt in flash. I have increased the JTAG clock divider but this does not solve the issue.

I read on the net (www.olimex.com/dev/pdf/lpc-h2129.pdf) that the LPC2129 is not reliable with an oscillator higher than 10Mhz. I have a 12Mhz quartz with 18pF capacitors, which seems like a typical setup, and I am wondering if this is why I am having issues with this processor…

Any idea of what is happening?

I have not had such issues with the LPC2148… Any difference between the 2?

I was thinking the assembly would be faulty so I checked all connections on the ARM (JTAG mainly). I also replaced the 18pF capacitors with 38pF.

I still have the same issue: the JTAG connection is intermittent, the chip can be programmed but blocks seem to fail the after programming check. some blocks seem to be blank…

Do I really need to switch to a 10Mhz quartz? Any other suggestion?