ez80190 ZiLOG Semiconductor, ez80190 Datasheet - Page 48

• Manufacturer Part Number: ez80190
• Description: Ez80190 Microprocessor
• Manufacturer: ZiLOG Semiconductor

PS006613-0306
Programmable Reload Timer Registers
Parameter
PRT Enabled
Reload and Restart Enabled
PRT Clock Divider = 2
Continuous Mode
PRT Interrupt Enabled
PRT Reload Value
Reading the Current Count Value
The eZ80
running. This READ event does not affect timer operation.
Timer Interrupts
The timer interrupt flag, PRT_IRQ, is set to 1 whenever the timer reaches its end-
of-count value,
value in CONTINUOUS mode. The timer interrupt flag is only set when the timer
reaches
when the timer is loaded with the value
out period.
The CPU can be programmed to poll the PRT_IRQ bit for the time-out event.
Alternatively, an interrupt service request signal can be sent to the CPU by setting
the IRQ_EN bit to 1. Then, when the end-of-count value,
the PRT_IRQ bit is set to 1, an interrupt service request signal is passed to the
CPU. The PRT_IRQ bit is cleared to 0 and the interrupt service request signal is
inactivated whenever the CPU reads from the timer control register, TMRx_CTL.
The response of the CPU to this interrupt service request is a function of the
CPU’s interrupt enable flag, IEF1. For more information, refer to the eZ80
User Manual.
Each programmable reload timer is controlled using five 8-bit registers. These
registers are the TIMERx Control register, TIMERx Reload Low Byte register, TIM-
ERx Reload High Byte register, TIMERx Data Low Byte register, and TIMERx
Data High Byte register. The variable x can be 0, 1, 2, 3, 4, or 5, representing each
of the 6 available timers.
Table 4. PRT Continuous Mode Operation Example
0000h
®
CPU is capable of reading the current count value while the timer is
0000h
(or reloads) from
, in SINGLE PASS mode, or when the timer reloads the start
Control Register(s)
TMRx_CTL[0]
TMRx_CTL[1]
TMRx_CTL[3:2]
TMRx_CTL[4]
TMRx_CTL[6]
{TMRx_RR_H, TMRx_RR_L}
PRELIMINARY
0001h
. The timer interrupt flag is not set to 1
0000h
, which selects the maximum time-
eZ80190 Product Specification
Programmable Reload Timers
0000h
Value
1
1
00b
1
0
0004h
, is reached and
®
CPU
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