Renesas RX Series User Manual

R01UH0823EJ0100 Rev.1.00 Page 1520 of 1823
Jul 31, 2019
RX23W Group 43. Capacitive Touch Sensing Unit (CTSU)
43.3.2.4 Self-Capacitance Multi-Scan Mode Operation
In self-capacitance multi-scan mode, electrostatic capacitance on all channels that are specified as measurement targets
by setting the CTSUCHACn and CTSUCHAC4 registers (n = 0 to 3) are measured sequentially in ascending order.
Figure 43.14 shows the software flowchart and an operation example, and Figure 43.15 shows the timing chart.
Figure 43.14 Software Flow and Operation Example of Self-Capacitance Multi-Scan Mode
Set interrupt operation
(DTC/ICU)
Set CTSU registers
Set CTSU control
(measurement start)
using CTSUCR0 register
CTSU operation starts
Power supply stabilization
time has elapsed after
CTSUPON = 1
• 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
Initial setting
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
Transferred by the DTC
when the DTC is set
Transferred by the DTC
when the DTC is set
CTSUSSC register
CTSUSO0 register
CTSUSO1 register
CTSUSC counter
CTSURC counter
Repeat for the number of
the measurement channels
Channel measurement sequence in self-capacitance multi-scan mode
Channel 3
Receive Channels
Channel 2 Channel 1 Channel 0
(1)
(2)
Channel 7 Channel 6 Channel 5 Channel 4
(3)(4)
When a software trigger is used, the CTSUCR0.CTSUSTRT bit is set to 0 when CTSU operation is finished.
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
CTSUCR1 register
• CTSUCR1.CTSUCLK[1:0] bits: Operating clock can be selected
• CTSUCR1.CTSUMD[1:0] bits: Set these bits to 01b
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
CTSUCHACn and CTSUCHAC4 registers (n = 0 to 3): Set the enabled channel
Setting
• Select self-capacitance multi-scan mode (CTSUCR1.CTSUMD[1:0] bits = 01b)
• Set channels 0, 3, 5, and 6 to enabled channels (CTSUCHACn.CTSUCHACn[7:0] bits (n = 0 to 3) = 01101001b)

Renesas RX Series Specifications

General

Brand	Renesas
Model	RX Series
Category	Microcontrollers
Language	English