Renesas RX Series User Manual

R01UH0823EJ0100 Rev.1.00 Page 816 of 1823
Jul 31, 2019
RX23W Group 29. Low-Power Timer (LPT)
29.3 Operation
29.3.1 Periodic Counting Operation
The low-power timer is a 16-bit up-counter that operates regardless of the MCU operating mode*
1
.
When the LPTCR3.LPCNTEN bit is set to 1 (low-power timer counter operates) after setting the
LPTCR1.LPCNTPSSEL[2:0] bits to select the division ratio, the LPTCR1.LPCNTCKSEL bit to select the clock source,
and the LPTCR2.LPCNTSTP bit to 0 (clock is supplied to the low-power timer), the low-power timer counter starts
counting with the selected clock.
When the value of the low-power timer counter matches the LPTPRD register value, the counter restarts counting from
0000h.
When the value of the low-power timer counter matches the LPCMR0 register value in software standby mode while the
LPTCR1.LPCMRE0 bit is set to 1 (Compare match 0 is enabled) and the LPWUCR.LPWKUPEN bit is set to 1 (wakeup
from software standby mode using low-power timer is enabled), the MCU returns from software standby mode to normal
operating mode by the function of the event link controller (ELC).
Figure 29.2 shows operation of the low-power timer and Figure 29.3 shows an example of procedure for the initial
settings.
Note 1. When the LPTCR1.LPCNTCKSEL bit is set to 1 (IWDT-dedicated clock), the counter stops because the
IWDTCLK stops in the low-power consumption mode under the following settings:
The OFS0.IWDTSLCSTP bit is set to 1 (counting stop is enabled) while IWDT is activated in auto-start mode, or
the IWDTCSTPR.SLCSTP bit is set to 1 (counting stop is enabled) while IWDT is activated in register start mode.
Figure 29.2 Operation of Low-Power Timer
LPTPRD
LPCMR0
0000h
Count starts
Normal
operating mode
Software standby mode
Normal
operating mode
Software standby mode
Normal
operating mode
Software standby
mode
Count value in low-power timer counter
Time
Counter is cleared when count value
matches LPTPRD value
Transitions to software standby
mode by executing WAIT instruction
Transitions to software standby
mode by executing WAIT instruction
Transitions to software standby
mode by executing WAIT instruction
ELC transits to active
state by compare match 0
ELC transits to active
state by compare match 0
ELC generates
interrupt request signal
ELC generates
interrupt request signal
Compare match
signal
MCU operating mode
Interrupt request
signal

Renesas RX Series Specifications

General

Core	RXv1, RXv2, RXv3
Flash Memory	Up to 8 MB
RAM	Up to 1 MB
Operating Voltage	1.62V to 5.5V
Operating Temperature	-40°C to +85°C or +105°C
Package	BGA, LQFP
ADC Resolution	12-bit
DAC Resolution	12-bit
Communication Interfaces	SCI, SPI, I2C, USB, Ethernet, CAN
Architecture	32-bit
Security Features	Memory Protection Unit (MPU)