JTAG problem with LPC1776

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by Alex on Mon Oct 07 04:44:40 MST 2013

I've designed an UART to ethernet converter using an LPC1776.

The boards are just coming out of factory and I'm trying to program the firmware into the LPC. But unfortunately JTAG doesn't work.

I'm using a SEGGER JLINK hardware revision 6.0 and IAR embedded workbench 6.5

I get two different errors when I try to connect to the LPC1776:
Mon Oct 07, 2013 12:27:26: Could not measure total IR len. TDO is constant high.
Mon Oct 07, 2013 12:27:26: Warning: At least one of the connected devices is not JTAG compliant (IEEE Std 1149.1, 7.1.1.d, IR-cells). (NumDevices = 4, NumBitsSet = 0)

I monitored the JTAG lines with my scope to verify the hardware is OK. The signals are looking quite well and all connections seem to be ok but the data on the TDO line makes no sense for me.

I attached a screenshot of my scope and a part of the schematics of the device.

Maybe somebody has got an idea.


Best regards,