
Interrupt Control Unit
7-18
7.3.5
Serial Port 0/1 Interrupt Control Registers
(SP0CON/SP1CON, Offset 44h/42h)
(Master Mode)
The serial port interrupt control registers control the operation of the serial ports’ interrupt
source (SP1 and SP0, bits 10–9 in the interrupt request register). Serial port 0 is assigned
to interrupt type 14h and serial port 1 is assigned to interrupt type 11h. The control register
format is shown in Figure 7-8.
Figure 7-8
Serial Port 0/1 Interrupt Control Register
The value of SP0CON and SPICON at reset is 001Fh.
Bits 15–5: Reserved—Set to 0.
Bit 4: Reserved—Set to 1.
Bit 3: Mask (MSK)—This bit determines whether the serial port can cause an interrupt. A
1 in this bit masks this interrupt source, preventing the serial port from causing an interrupt.
A 0 in this bit enables serial port interrupts.
This bit is duplicated in the Interrupt Mask register. See the Interrupt Mask register in Section
7.3.10 on page 7-24.
Bits 2–0: Priority (PR2–PR0)—This field determines the priority of the serial port relative
to the other interrupt signals. After a reset, the priority is 7. See Table 7-3.
Table 7-3
Priority Level
Priority
PR2–PR0
(High) 0
0 0 0b
1
0 0 1b
2
0 1 0b
3
0 1 1b
4
1 0 0b
5
1 0 1b
6
1 1 0b
(Low) 7
1 1 1b
15
7
0
MSK
Res
Reserved
1
PR2
PR1
PR0
Содержание Am186 ES
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