Z86D990 Datasheet, PDF (79/102 Pages) Zilog, Inc. – Low-Voltage Micro controllers with ADC

Z86D990/Z86D991 OTP and Z86L99X ROM
Low-Voltage Microcontrollers with ADC
72
T1 Data Register (T1)
The counter/timer register (T1) consists of an 8-bit down counter, a write-only reg-
ister that holds the initial count value, and a read-only register that holds the cur-
rent count value. The initial value of T1 can range from 1 to 255 (0 represents
256) (see Table 34.)
Table 34. T1 Register [Group/Bank F0h, Register 2 (R242)]
Bit
7
6
5
4
3
2
1
0
Bit/Field T1_Value
R/W
R/W R/W R/W R/W R/W R/W R/W R/W
Reset
0
0
0
0
0
0
0
0
R = Read, W = Write, X = Indeterminate
Bit
Position
76543210
Bit/Field
T₁ Value
R/W Value Description
R
Data Current Value
W
Data Initial Value (Range 1 to 256 Decimal)
T1 Mode Register (TMR)
Under software control, T1 counter/timer is started and stopped using the T1
Mode Register as shown in Table 35.
Table 35. TMR Register [Group/Bank F0h, Register 1 (R241)]
Bit
7
6
5
4
Bit/Field TOUT_Mode TIN_Mode
R/W
R/W R/W R/W R/W
Reset
0
0
0
0
R = Read, W = Write, X = Indeterminate
Bit
Position
Bit/Field
R/W Value
76______ T_OUT Mode
R/W 11
10
01
00
__54____ T_IN Mode
R/W 11
10
01
00
____3___ T₁ Count
R/W 1
0
3
T1_
Count
R/W
0
2
T1_
Load
R/W
0
1
0
Reserved
R/W R/W
1
1
Description
Internal Clock OUT on P56
T₁OUT on P56
Reserved
Not used (P56 configured as I/O)
Trigger Input (Retriggerable)
Trigger Input (Not-retriggerable)
Gate Input
External Clock Input (T_IN on P52)
Enable T₁ Count
Disable T₁ Count
PS003807-1002
PRELIMINARY