6 ie1, Table 8. ie1 special function register definitions, 7 iph1 – Intel 8xC251TB User Manual
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8xC251Tx Hardware Description
3.2.6
IE1
Address: B1H
Reset Value: xxxx xxx0B
3.2.7
IPH1
Address: B3H
Reset Value: xxxx xxx0B
3.2.8
IPL1
Address: B2H
Reset Value: xxxx xxx0B
Interrupt priority of the second serial I/O port can be programmed to one of four levels depending on the
IPH1.0 and IPL1.0 bits.
Table 8. IE1 Special Function Register Definitions
Bit Number
Bit Mne-
monic
Function
7 - 1
-
Reserved
0
ES1
Second serial I/O port Interrupt Enable:
Setting this bit enables the second serial I/O port interrupt
Table 9. IPH1 Special Function Register Definitions
Bit Number
Bit Mne-
monic
Function
7 - 1
-
Reserved
0
IPH1.0
Second serial I/O port Interrupt Priority High Bit
Table 10. IPL1 Special Function Register Definitions
Bit Number
Bit Mne-
monic
Function
7 - 1
-
Reserved
0
IPL1.0
Second serial I/O port Interrupt Priority Low Bit
Table 11. Interrupt Priority of Second Serial I/O Port
IPH1.0
IPL1.0
Priority Level
0
0
0 (Lowest Priority)
0
1
1
1
0
2
1
1
3 (Highest Priority)