ISP mode troubles with NGX LPC1857-Xplorer++ board

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by inflames on Mon Dec 16 03:29:43 MST 2013
Hi all,

I have a big problem with a NGX LPC1857-Xplorer++ board.

I can't get debug access to the MCU using my Segger J-Link debugger (it works fine with others boards, Embedded Artists LPC4357 eval board, for example).

NXP says that the classic cases of this could be the following:
- The image contains code that sets the MCU clocks up "incorrectly".
- The image contains code that enables a watchdog timer.
- The image contains code that "switches off" some, or all of the multiplexed debug pins (JTAG/SWD).

The first thing to try with NXP LPC MCU's to recover debug access is to boot into the ISP bootloader.

I have to put P2_7 (H14, EMC_A9) low during a power-up in order to run ISP mode, but according to the datasheet the aforementioned pin is not available on the headers neither on a button.

Is there any reason for that?
Is there any other way to get ISP access with this board? I can't enter ISP mode with DFU utils or FLASHMAGIC tool (using UART3).

Best regards