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4.1 Definition
The definition of I/O expansion bus is given as following:
J1 pin definition & description:
No Name
Description
1
GND
Ground of PCB
2
GND
Ground of PCB
3
CLOCKA Synchronous clock output of CPU
4
ARDY
Asynchronous ready input (active low)
5
INT0
Interrupt request input of channel 0 (asynchronous, active high)
6
INT1
Interrupt request input of channel 1 (asynchronous, active high)
7
VCC
Power supply of PCB
8
RESET
System reset (active high)
9
GND
Ground of PCB
10 /RESET
System reset (active low)
11 TO_1
Timer output 1 of CPU(can be used as programmable D/I/O)
12 TO_0
Timer output 0 of CPU(can be used as programmable D/I/O)
13 TI_1
Timer input 1 of CPU(can be used as programmable D/I/O)
14 TI_0
Timer input 0 of CPU(can be used as programmable D/I/O)
15 SCLK
Common serial clock output of 7188 series
16 DIO9
Programmable
D/I/O
bit
17 DIO4
Programmable
D/I/O
bit
18 DIO14
Programmable
D/I/O
bit
19 VCC
Power supply of PCB
20 VCC
Power supply of PCB
•
CLOCKA: 20M for 7188XC, 40M for 7188XA/B & 7188EA/X
•
ARDY: let this pin OPEN for no wait states applications
•
INT0, INT1: let these two pins OPEN for no interrupt applications
•
TO_0, TO_1: can be used as CPU’s timer output or programmable D/I/O
•
TI_0, TI_1: can be used as CPU’s timer input or programmable D/I/O
•
DIO4, DIO9, DIO14: programmable D/I/O bit
•
SCLK: the 7188X/7188E series use this signal as a CLOCK source to drive all on-
board serial devices, so it is always be programmed as D/O. Changing this signal to
other configuration will cause serious errors. Users can use this signal to drive external
serial devices without any side effects.
Note:
Pin number of the TO_0, TO_1, TI_0, and TI_1 of the 7188EX and
7188XB are different.
7188E Series Hardware User’s Manual, 2004, v2.2, 7MH-016-22 ----- 42