Renesas RX Series User Manual

R01UH0823EJ0100 Rev.1.00 Page 1518 of 1823
Jul 31, 2019
RX23W Group 43. Capacitive Touch Sensing Unit (CTSU)
43.3.2.3 Self-Capacitance Single Scan Mode Operation
In self-capacitance single scan mode, electrostatic capacitance on a channel is measured. Figure 43.12 shows the
software flowchart and an operation example, and
Figure 43.13 shows the timing chart.
Figure 43.12 Software Flowchart and Operation Example of Self-Capacitance Single Scan Mode
Self-capacitance single scan mode
Set interrupt operation
(DTC/ICU)
Set CTSU registers
Set CTSU control
(measurement start)
using CTSUCR0 register
CTSU operation starts
CTSUFN generated?
No
Touch determination
processing
Wait for the measurement end interrupt
CTSURD generated?
No
CTSUWR interrupt
generated?
No
Read the measurement result
Set the measurement channel
CTSUSSC register
CTSUSO0 register
CTSUSO1 register
CTSUSC counter
CTSURC counter
Transferred by the DTC
when the DTC is set
Transferred by the DTC
when the DTC is set
Initial setting
When a software trigger is used, the CTSUCR0.CTSUSTRT bit is set to 0 when CTSU operation is finished.
• CTSUWR interrupt operation setting
Transfer from the RAM to the CTSUSSC, CTSUSO0, and CTSUSO1 registers
• CTSURD interrupt operation setting
Transfer the CTSUSC and CTSURC counters to the RAM
CTSUCR1 register
• CTSUCR1.CTSUCLK[1:0] bits: Operating clock can be selected
• CTSUCR1.CTSUMD[1:0] bits: Set these bits to 00b
CTSUSDPRS register
• CTSUSDPRS.CTSUSOFF bit: High-pass noise prevention can be turned off
• CTSUSDPRS.CTSUPRMODE[1:0] bits: Set the number of base pulses for synchronous noise prevention
• CTSUSDPRS.CTSUPRRATIO[3:0] bits: Set the measurement time for synchronous noise prevention
CTSUSST register: Set the sensor stabilization time
CTSUMCH0 register: Set the measurement channel
• CTSUCR0.CTSUSTRT bit: Set this bit to 1
• CTSUCR0.CTSUCAP bit: Starting CTSU operation by external trigger can be selected
• CTSUCR0.CTSUSNZ bit: Power-saving function during wait state can be enabled or disabled
Power supply stabilization
time has elapsed after
CTSUPON = 1
CTSUCHACn and CTSUCHAC4 registers (n = 0 to 3): Set the enabled channel

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)