ez80l92 ZiLOG Semiconductor, ez80l92 Datasheet - Page 87

• Manufacturer Part Number: ez80l92
• Description: Ez80acclaim Flash Microcontrollers
• Manufacturer: ZiLOG Semiconductor

PS013014-0107
PRT Count
PRT Clock
(Clock
IOWRN
Output
Value
Timer
CLK
4)
Event Counter
When Timers 0–3 are configured to take their inputs from port input pins PB0 and PB1,
they function as event counters. For event counting, the clock prescaler is bypassed.
The PRT counters decrement on every rising edge of the port pin. The port pins must
be configured as inputs. Due to the input sampling on the pins, the event input signal fre-
quency is limited to one-half the system clock frequency. Input sampling on the port pins
results in the PRT counter being updated on the fifth rising edge of the system clock after
the rising edge occurs at the port pin.
Timer Output
Two of the Programmable Reload Timers (Timers 4 and 5) can be directed to GPIO Port B
output pins (PB4 and PB5, respectively). To enable the Timer Out feature, the GPIO port
pin must be configured for alternate functions. After reset, the Timer Output feature is
disabled by default. The GPIO output pin toggles each time the PRT reaches its end-of-
count value. In CONTINUOUS mode operation, the disabling of the Timer Output feature
results in a Timer Output signal period that is twice the PRT time-out period. Examples of
the Timer Output operation are illustrated in
the GPIO output is assumed to be Low (0) when the Timer Output function is enabled.
Table 31. PRT Timer Out Operation Example
Parameter
PRT Enabled
Reload and Restart Enabled
Figure 21. PRT Timer Output Operation Example
X
I/O Write to TMRx_CTL Enables PRT
3
2
Control Register(s)
TMRx_CTL[0]
TMRx_CTL[1]
Figure 21
1
and
3
Table
Programmable Reload Timers
Product Specification
31. In these examples,
2
Value
1
1
eZ80L92 MCU
1
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