Content originally posted in LPCWare by NXP_Paul on Thu Sep 19 08:51:27 MST 2013
The issue was that PIO0_1 and ACMP_I2 share the same pin. The ACMP_I2 function cannot be moved to another pin (it is a fixed function). In many applications, the analog comparator input will be required, and may be low during reset. If the comparator input was low, it would cause the device to enter ISP mode. PIO0_12 does not have any fixed function associated with it, so it is safer to use for entry into ISP.
- Paul