Content originally posted in LPCWare by J@N on Fri Apr 17 16:16:57 MST 2015
Hi,
I've made my own board with LPC4357. JTAG, LCD, SDRAM (as frame buffer), GPIO works well, the only problem was with RTC (another post). I already know that it was because of bad PCB design or bad valued loading capacitors. There are LCD data wires near the RTC crystal and if I turned the LCD controller off (or make a black screen), RTC works OK.
I wanted to show the RTC crystal signal, so I used an oscilloscope. The microcontroller ran (only turning off/on a LED after a second), RTC was already initialized. I connected probe to RTCX1, then to RTCX2; and then probe to RTCX2 and ground to RTCX1 in the end. The microcontroller stoped working then. I don't know when - if it was by the last oscilloscope connection or after next microcontroller reset. I definitely know that I didn't connect the oscilloscope to another wires than above described. No short circuit.
The microcontroller doesn't run now and I couldn't program it (LPCXpresso/uVision, LPC-LINK2). I also tried manually pull-down P2_7 by reset and then program it, but it didn't help too.
LPCXpresso writes "Error reported by server (redlinkserv.exe): RedlinkAPI: Hardware interface transfer error" or "Error: Read timed out".
uVision writes:"SWD/JTAG Communication Failure".
Could I demage the microcontroller when I used the oscilloscope?
I already had a similar problem, but it was coused by a wrong IC that sometimes held the NRESET continuously in logic zero. NRESET is OK now.
Do you have any tips what can I try?
Thanks.
Honza
