Z8 Microcontrollers
Interrupts
ZiLOG
7-6
UM001600-Z8X0599
7.4 INTERRUPT INITIALIZATION
(Continued)
7.4.2 Interrupt Mask Register (IMR) Initialization
IMR individually or globally enables or disables the six in-
terrupt requests (Figure 7-8). When bit 0 to bit 5 are set to
1, the corresponding interrupt requests are enabled. Bit 7
is the master enable and must be set before any of the in-
dividual interrupt requests can be recognized. Resetting
bit 7 globally disables all the interrupt requests. Bit 7 is set
and reset by the EI and DI instructions. It is automatically
reset during an interrupt service routine and set following
the execution of an Interrupt Return (IRET) instruction.
Note:
Bit 7 must be reset by the DI instruction before the
contents of the Interrupt Mask Register or the Interrupt
Priority Register are changed except:
Immediately after a hardware reset.
Immediately after executing an interrupt service routine
and before IMR bit 7 has been set by any instruction.
Note:
The RAM Protect option is selected at ROM mask
submission time or at EPROM program time. If not
selected or not an available option, this bit is reserved and
must be 0.
Figure 7-8. Interrupt Mask Register
D7 D6 D5 D4 D3 D2 D1 D0
(Read/Write)
Interrupt Request Register (IMR)
Register FBH
0 = Disables IRQ0
1 = Enables IRQ0
0 = Disables IRQ1
1 = Enables IRQ1
0 = Disables IRQ2
1 = Enables IRQ2
0 = Disables IRQ3
1 = Enables IRQ3
0 = Disables IRQ4
1 = Enables IRQ4
0 = Disables IRQ5
1 = Enables IRQ5
0 = Disables RAM Protect
1 = Enables RAM Protect
0 = Disables Interrupt
1 = Enables Interrupt