5. Counter/Timers
ÛZIATECH
42
Auxiliary Counter/Timer (CTC 2) Architecture
8907
10
6
8
9
4
5
7
3
1
2
OUT0
8 MHz Oscillator
CLK2
OUT2
GAT2
OUT1
GAT1
CLK1
CT4
CT5
CT6
Base Address: E8h
Counter/Timer
GAT0
CLK0
Interrupt Output
OUT0
GAT2
OUT2
CLK2
CLK1
GAT1
OUT1
Frontplane J2
CLK0
GAT0
CT0
CT1
CT2
CTC2 Timer 2 = IRQ15 Default
CTC2 Timer 1
CTC2 Timer 0
System Register 1
Note:
= 10 k
Ω
pull-up resistor.
= Programmable
PROGRAMMABLE REGISTERS
The user-available auxiliary counter/timers are accessed through four I/O addresses, as
shown in the "Auxiliary Counter/Timer (CTC 2) Register Addressing" table below. Each
counter/timer occupies an I/O port address through which the preset count values are
written and both the count and status information is read. The control register occupies
the remaining I/O port address, which services all three counter/timers.
Auxiliary Counter/Timer (CTC 2) Register Addressing
Address
Register
Operation
00E8h
Channel 0 Count
Read/Write
00E8h
Channel 0 Status
Read
00E9h
Channel 1 Count
Read/Write
00E9h
Channel 1 Status
Read
00EAh
Channel 2 Count
Read/Write
00EAh
Channel 2 Status
Read
00EBh
Control
Write