R01UH0823EJ0100 Rev.1.00
Page 1510 of 1823
Jul 31, 2019
RX23W Group
43. Capacitive Touch Sensing Unit (CTSU)
43.2.17
CTSU Reference Counter (CTSURC)
Read first from the CTSUSC counter and then the CTSURC counter after a CTSURD interrupt is generated.
Even when the stabilization time specified for Status 3 has elapsed, if the CTSURC counter is not read, Status 3
continues until the counter is read.
CTSURC[15:0] Bits (CTSU Reference Counter)
These bits are configured as an increment counter that counts the reference ICO clock.
The reference ICO is used to optimize touch measurement performed using the sensor ICO. There is some deviation
depending on the internal sensor ICO and the reference ICO in the CTSU, but both ICOs have almost the same
characteristics, and the dynamic range and the current to frequency characteristics are almost the same. The range of
current amount that can be set by the reference ICO current adjustment bits is about the same as the range of both ICOs,
and the current amount input to the sensor ICO must be within this dynamic range. First, use the reference ICO to check
the differences between the ICOs and measure the current to oscillation frequency characteristics. Since the reference
ICO oscillation frequency can be obtained from the reference ICO counter, the ICO oscillation frequency (counter value/
measurement time) for the input current amount can be measured by setting the value in the reference ICO current
adjustment bits and measuring the reference ICO counter. The reference ICO counter value measured using the
maximum value of the reference ICO current adjustment bits is the maximum value of the ICO dynamic range.
Therefore, the current amount of the sensor ICO needs to be offset by setting the offset adjustment bits so that the sensor
ICO counter value does not exceed this value.
Read the CTSURC[15:0] bits after a CTSURD interrupt is generated. After these bits are read, they are cleared
immediately before the CTSU measurement status counter value changes to Status 4 (the CTSUST.CTSUSTC[2:0] flags
changes to 100b) in the next measurement. These bits are also cleared using the CTSUCR0.CTSUINIT bit.
Address(es): CTSU.CTSURC 000A 091Ah
b15
b14
b13
b12
b11
b10
b9
b8
b7
b6
b5
b4
b3
b2
b1
b0
CTSURC[15:0]
Value after reset:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Bit
Symbol
Bit Name
Description
R/W
b15 to b0
CTSU Reference Counter
These bits indicate FFFFh when an overflow occurs.
R