Rainbow Electronics W78C438C - Manual (Page 9)

W78C438C
Publication Release Date: July 1998
- 9 - Revision A1
BIT ADDR. NAME FUNCTION
7 0C7H PX3
High/low priority level for INT3 is specified when this bit is set/cleared by software.
6 0C6H EX3
Enable/disable interrupt from INT3 when this bit is set/cleared by software.
5 0C5H IE3 If IT3 is "1," IE3 is set/cleared automatically by hardware when interrupt is
detected/serviced.
4 0C4H IT3
INT3 is falling-edge/low-level triggered when this bit is set/cleared by software.
3 0C3H PX2 High/low priority level for INT2 is specified when this bit is set/cleared by software.
2 0C2H EX2
Enable/disable interrupt from INT2 when this bit is set/cleared by software.
1 0C1H IE2 If IT2 is "1," IE2 is set/cleared automatically by hardware when interrupt is
detected/serviced.
0 0C0H IT2
INT2 is falling-edge/low-level triggered when this bit is set/cleared by software.
Table 2. Functions of XICON Register
INTERRUPT SOURCE VECTOR ADDRESS PRIORITY SEQUENCE
External Interrupt 0 03H 0 (Highest)
Timer/Counter 0 0BH 1
External Interrupt 1 13H 2
Timer/Counter 1 1BH 3
Serial Port 23H 4
Timer/Counter 2 2BH 5
External Interrupt 2 33H 6
External Interrupt 3 3BH 7 (Lowest)
Table 3. Priority of Interrupts
Newly Added Special Function Registers
The W78C438C uses four newly defined special function registers, which are described in Table 4. To
read/write these registers, use the "MOV direct" or "read-modify-write" instructions.
REGISTER ADDR. FUNCTION LENGTH R/W
TYPE
VALUE
AFTER
RESET
1 HB A1H During the execution of "MOVX @Ri," the content of HB is output to
AP6. 8 R/W 00H
2 EPMA A2H EPMA.7 determines functions of AP7.
EPMA.3 −EPMA.0 determine values of AP7<3:0> when EPMA.7 is
"0."
8 R/W 70H
3 P8 A6H The content of P8 is output to port 8. 8 R/W 0FFH
4 XICON C0H
The bits of XICON determine/show the functions/status of INT2 −
INT3 . Bit-addressable.
8 R/W 00H
Table 4. Newly Added Special Function Registers of the W78C438C