MS82C55A_06 Datasheet, PDF (6/26 Pages) Intersil Corporation – CMOS Programmable Peripheral Interface

MS82C55A, MQ82C55A, MP82C55A
CONTROL WORD
D7 D6 D5 D4 D3 D2 D1 D0
XX X
DON’T
CARE
BIT SET/RESET
1 = SET
0 = RESET
BIT SELECT
01234567
0 1 0 1 0 1 0 1 B0
0 0 1 1 0 0 1 1 B1
0 0 0 0 1 1 1 1 B2
BIT SET/RESET FLAG
0 = ACTIVE
FIGURE 5. BIT SET/RESET FORMAT
Interrupt Control Functions
When the 82C55A is programmed to operate in mode 1 or
mode 2, control signals are provided that can be used as
interrupt request inputs to the CPU. The interrupt request
signals, generated from port C, can be inhibited or enabled
by setting or resetting the associated INTE flip-flop, using
the bit set/reset function of port C.
This function allows the programmer to enable or disable a
CPU interrupt by a specific I/O device without affecting any
other device in the interrupt structure.
INTE Flip-Flop Definition
(BIT-SET)-INTE is SET - Interrupt Enable
(BIT-RESET)-INTE is Reset - Interrupt Disable
NOTE: All Mask flip-flops are automatically reset during mode
selection and device Reset.
Operating Modes
Mode 0 (Basic Input/Output). This functional configuration
provides simple input and output operations for each of the
three ports. No handshaking is required, data is simply
written to or read from a specific port.
Mode 0 Basic Functional Definitions:
• Two 8-bit ports and two 4-bit ports
• Any Port can be input or output
• Outputs are latched
• Inputs are not latched
• 16 different Input/Output configurations possible
A
D4 D3
00
00
00
00
01
01
01
01
10
10
10
10
11
11
11
11
MODE 0 PORT DEFINITION
B
GROUP A
GROUP B
PORT C
PORT C
D1 D0 PORT A (Upper) # PORT B (Lower)
0 0 Output Output 0 Output Output
0 1 Output Output 1 Output Input
1 0 Output Output 2 Input Output
1 1 Output Output 3 Input Input
0 0 Output Input 4 Output Output
0 1 Output Input 5 Output Input
1 0 Output Input 6 Input Output
1 1 Output Input 7 Input Input
0 0 Input Output 8 Output Output
0 1 Input Output 9 Output Input
1 0 Input Output 10 Input Output
1 1 Input Output 11 Input Input
0 0 Input Input 12 Output Output
0 1 Input Input 13 Output Input
1 0 Input Input 14 Input Output
1 1 Input Input 15 Input Input
Mode 0 (Basic Input)
RD
INPUT
CS, A1, A0
D7-D0
tRR
tIR
tHR
tAR
tRA
tRD
tDF
6
FN6140.2
June 15, 2006