Z86L972 Datasheet, PDF (73/91 Pages) Zilog, Inc. – Low-Voltage Microcontrollers

Z86L972/Z86L973/Z86L974
Low-Voltage Microcontrollers
66
Table 33. TMR Register [Group/Bank F0h, Register 1 (R241)] (Continued)
_____2__ T₁ Load
______10 Reserved
R/W 1
0
R
1
W
X
Load T₁
No effect
Always reads 11
No effect
T1 Prescale Register (PRE1)
The T1 prescaler consists of an 8-bit register and a 6-bit down-counter. The six
most significant bits (D2–D7) of PRE1 hold the prescaler’s count modulo, a value
from 1 to 64 decimal, as shown in Table 34. The prescale register also contains
control bits that specify the counting mode and clock source for T1.
Table 34. PRE1 Register [Group/Bank F0h, Register 3 (R243)]
Bit
7
6
5
4
Bit/Field Prescaler_Modulo
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
765432__ Prescaler Modulo R/W Data
_______1_ Clock Source
R/W 1
0
________0 Count Mode
R/W 1
0
3
2
1
0
Clock_ Count_
Source Mode
R/W R/W R/W R/W
0
0
0
0
Description
Range: 1 to 64 Decimal
T₁ Internal
T₁ External (T_IN on P52)
T₁ Modulo-n
T₁ Single Pass
Timer Control Registers—T8 and T16 Timers
One of the unique features of the Z86L972/Z86L973/Z86L974 family is a special
timer architecture to automate the generation and reception of complex pulses or
signals. This timer architecture consists of one programmable 8-bit counter timer
with two capture registers and two load registers and a programmable 16-bit
counter/timer with one 16-bit capture register pair and one 16-bit load register pair
and their associated control registers. These counter/timers can work indepen-
dently or can be combined together using a number of user-selectable modes
governed by the T8/T16 control registers.
PS010504-1002
PRELIMINARY