Content originally posted in LPCWare by nxp_apps on Thu May 01 11:52:37 MST 2014
Hi,
If a pin is configured as GPIO input, a write to the GPIODATA register has no effect on the pin level.
A read of the GPIODATA register returns the current state of the pin.
Also, additional information for you is masked read operation:
If the address bit associated with the GPIO data bit is HIGH, the value is read.
If the address bit is LOW, the GPIO data bit is read as 0: Reading a port DATA register yields the state of port pins 11:0 ANDed with address bits 13:2.
Please see masked read operation in the user manual (in particular Figure 15).
Hope this helps.
Thanks.
nxp_support