Interrupt mask register for port n
| MASK0 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK1 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK2 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK3 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK4 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK5 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK6 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK7 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK8 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK9 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK10 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| MASK11 | Selects interrupt on pin x to be masked (x = 0 to 11). 0 = Interrupt on pin PIOn_x is masked. 1 = Interrupt on pin PIOn_x is not masked. | 
| RESERVED | Reserved |