How to config LPC1850 ISP pin (P2_7) from EMC A9

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by hitpony on Sun Nov 09 10:06:47 MST 2014
I am using LPC1850, and P2_7 is used as A9 of EMC, and at the beginning of the program, EMC is initialized, and program needs to access to EMC for some global variable initialization, after that, a watchdog is started, and needs to change P2_7 from EMC_A9 to GPIO0[7], and set to HIGH, in order to let the watchdog trigger the reset and enter the bootloader again (I do not want to enter ISP after watchdog). in the UM10430, P2_7 GPIO0[7] described as:

GPIO0[7] — General purpose digital input/output pin. ISP entry pin. If this pin is pulled LOW at reset, the part enters ISP mode using USART0.

Does anyone know how can I reconfigure P2_7 from EMC_A9 to GPIO0[7]? do I needs to stop EMC controller? In the HW, P2_7 is connected to EMC (a NORFLASH) only, and no switch connected to it, so I can NOT force to pull it HIGH via HW, I am wonderring whether I can pull it HIGH via SW, and what is the best steps to do it under such HW design?

Thanks in advance!