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i.MX25: How to read GPIO Interrupt Status Register

Question asked by Nori Shinozaki on Apr 15, 2015
Latest reply on Apr 17, 2015 by Nori Shinozaki

Hello Champs,


In the I.MX257 PDK, I breaked at 0x00000000 by JTAG and read GPIO-4 register.


It read:

                              DR        GDIR          PSR          ICR1

0x53F9C000: 20000000 00000000 20000000 00000000


                             ICR2         IMR          ISR

0x53F9C010: 00000000 00000000 DFFFFFFF 00000000


0x20000000 in PSR means gpio4_GPIO[29] is enabled in IOMUXC.

The corresponding DR bit is set, because it's default direction is input and data is sensed at the pad pin.


Now in the ISR, the 29 bit looks cleard 


In Reference Manual, the default values of ISR is 0, however it looks 1 is the default/reset value.


Could you explain how to read ISR register?


Best regards,

Nori Shinozaki