z8pe003 ZiLOG Semiconductor, z8pe003 Datasheet - Page 30

• Manufacturer Part Number: z8pe003
• Description: Feature-enhanced Z8plus 1k Rom One-time Programmable Otp Microcontroller
• Manufacturer: ZiLOG Semiconductor

TIMERS (Continued)
Z8PE002
Z8Plus OTP Microcontroller
A pair of
timer. One register is defined to contain the auto-initializa-
tion value for the timer. The second register contains the
current value for the timer. When a timer is enabled, the tim-
er decrements the value in its count register and continues
decrementing until it reaches
and the contents of the auto-initialization register are op-
tionally copied into the count value register. If auto-initial-
ization is not enabled, the timer stops counting when the val-
ue reaches
register bit to disable the timer. This operation is referred
to as a single-shot. If auto-initialization is enabled, the timer
counts from the initialization value. Software must not at-
tempt to use timer registers for any other function.
User software is allowed to write to any
any time; however, care should be taken if timer registers
are updated while the timer is enabled. If software changes
the count value while the timer is in operation, the timer con-
tinues counting from the updated value.
30
READ/WRITE
0
. Control logic clears the appropriate control
0C0
D7
Note: Timer T01 is a 16-bit PWM Timer formed by cascading 8-bit timers
D6
registers is utilized for each 8-bit
T1 (MSB) and T0 (LSB). T23 is a standard 16-bit timer formed
by cascading 8-bit timers T3 (MSB) and T2 (LSB).
0
D5
. An interrupt is generated,
D4
WRITE
TCTLLO
D3
Figure 22. TCTLLO Register
register at
P R E L I M I N A R Y
D2
D1
D0
Note: Unpredictable behavior can occur if the value updates at
Similarly, if user software changes the initialization value
register while the timer is active, the next time that the timer
reaches
Note: Unpredictable behavior can occur if the initialization
The initialization value is determined by the exact timing
of the
higher priority to the software
write-back. However, when hardware clears a control reg-
ister bit for a timer that is configured for single-shot oper-
ation, the clearing of the control bit overrides a software
WRITE
time, with no effect on the functionality of the timer.
WRITE
the same time that the timer reaches
value register is changed while the timer is in the process
of being initialized.
. A
D2 D1 D0
---- ---- ---- ------------- ------------- ---------------
0
0
0
0
0
1
1
1
1
N
Reserved (must be 0)
1 = T23 16-Bit Timer Enabled with Auto-Reload Active
0 = T2 and T3 Timers Disabled
Reserved (must be 0)
, the timer initializes to the changed value.
OTE
READ
0
0
1
1
0
0
1
1
: (*) indicates auto-reload is active.
operation. In all cases, the Z8Plus assigns a
0
1
0
1
0
1
0
1
of either register can be conducted at any
Disabled Disabled
Enabled
Disabled Enabled
Enabled
Enabled* Disabled
Disabled Enabled*
Enabled* Enabled*
TIMER STATUS
T0
Disabled
Enabled
T1
WRITE
Enabled*
than to a decrementer
DS008700-Z8X0799
T01
0
.
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