Hi
This sounds to be normal operation. GPIOC_PSOR is the Set Output Register, causing the bit with '1' to be set to the output; the register itself always reads 0.
Since the write set the bit in the output, this is seen in the GPIOC_PDORC register.
By contrast, if you write "GPIOC_PCOR = 1" it will then clear the bit in the GPIOC_PDORC register.
Furthermore "GPIOC_PTOR = 1" will toggle the bit.
Regards
Mark
