ez80l92 ZiLOG Semiconductor, ez80l92 Datasheet - Page 83

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

Programmable Reload Timers
PS013014-0107
System Clock
RTC Source
GPIO Pin
Programmable Reload Timer Operation
(Timers 0—3
The eZ80L92 MCU features six Programmable Reload Timers (PRT). Each PRT contains
a 16-bit downcounter and a 16-bit reload register. In addition, each PRT features a clock
prescaler with four selectable taps for CLK ÷ 4, CLK ÷ 16, CLK ÷ 64, and CLK ÷ 256.
Each timer can be individually enabled to operate in either SINGLE PASS or
CONTINUOUS mode. The timer can be programmed to start, stop, restart from the
current value, or restart from the initial value, and generate interrupts to the CPU.
Four of the Programmable Reload Timers (timers 0–3) feature a selectable clock source
input. The input for these timers can be either the system clock or the Real-Time Clock
(RTC) source. Timers 0–3 can also be used for event counting, with their inputs received
from a GPIO port pin. Output from timers 4 and 5 can be directed to a GPIO port pin.
Each of the six PRTs available on the eZ80L92 can be controlled individually. They do not
share the same counters, reload registers, control registers, or interrupt signals.
A simplified block diagram of a programmable reload timer is illustrated in
Setting Timer Duration
There are three factors to consider when determining Programmable Reload Timer
duration—clock frequency, clock divider ratio, and initial count value. Minimum duration
TMRx_IN
only)
2
Figure 18. Programmable Reload Timer Block Diagram
TMRx_CTL[3:2]
Adjustable
Prescaler
Clock
2
{TMRx_DR_H, TMRx_DR_L}
{TMRx_RR_H, TMRx_RR_L}
Reload Registers
Data Registers
Down Counter
Data[7:0]
Data[7:0]
16-Bit
Control Register
Control Logic
TMRx_CTL
Data[7:0]
PRT
(Timers 4—5 only)
Programmable Reload Timers
TOUT_EN
Product Specification
eZ80L92 MCU
IRQ to eZ80 CPU
Timer Out
Figure
18.
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