R01UH0823EJ0100 Rev.1.00
Page 606 of 1823
Jul 31, 2019
RX23W Group
23. Multi-Function Timer Pulse Unit 2 (MTU2a)
23.6.19
Notes on Transition from Normal Mode or PWM Mode 1 to Reset-Synchronized
PWM Mode
When making a transition from normal mode or PWM mode 1 to reset-synchronized PWM mode in MTU3 and MTU4,
if the counter is stopped while the output pins (MTIOC3B, MTIOC3D, MTIOC4A, MTIOC4C, MTIOC4B, and
MTIOC4D) are held at a high level and then operation is started after a transition to reset-synchronized PWM mode, the
initial pin output will not be correct.
When making a transition from normal mode to reset-synchronized PWM mode, write 11h to registers MTU3.TIORH,
MTU3.TIORL, MTU4.TIORH, and MTU4.TIORL to initialize the output pin state to a low level, then set the registers to
the initial value (00h) before making the mode transition.
When making a transition from PWM mode 1 to reset-synchronized PWM mode, switch to normal mode, initialize the
output pin state to a low level, and then set the registers to the initial value (00h) before making the transition to reset-
synchronized PWM mode.
23.6.20
Output Level in Complementary PWM Mode or Reset-Synchronized PWM
Mode
When complementary PWM mode or reset-synchronized PWM mode is selected for MTU3 or MTU4, use the
TOCR1.OLSP bit and TOCR1.OLSN bit to set the levels for PWM waveform output. Also, when either of these modes
is in use, set the TIOR register to 00h. The negative-phase output level when the TDER.TDER bit is set to 0 (no dead
time is generated) in complementary PWM mode is the inverse of the positive-phase output level according to the
TOCR1.OLSP bit setting, not the TOCR1.OLSN bit setting.
23.6.21
Interrupts during Periods in the Module Stop State
When an module that has issued an interrupt request enters the module stop state, clearing the source of the interrupt for
the CPU or activation signal for the DTC/DMAC is not possible.
Accordingly, disable interrupts, etc. before making the settings for the module stop state.
23.6.22
Simultaneous Input Capture in MTU1.TCNT and MTU2.TCNT in Cascade
Connection
When counters MTU1.TCNT and MTU2.TCNT operate as a 32-bit counter in cascade connection, the cascaded counter
value cannot be captured successfully in some cases even if input-capture input is simultaneously done to MTIOC1A and
MTIOC2A or to MTIOC1B and MTIOC2B. This is because the input timing of MTIOC1A and MTIOC2A or of
MTIOC1B and MTIOC2B may not be the same when external input-capture signals input into counters MTU1.TCNT
and MTU2.TCNT are taken in synchronization with the internal clock.
For example, the MTU1.TCNT counter (the counter for upper 16 bits) does not capture the count-up value by an
overflow from the MTU2.TCNT counter (the counter for lower 16 bits) but captures the count value before the up-
counting. In this case, the values of MTU1.TCNT = FFF1h and MTU2.TCNT = 0000h should be transferred to registers
MTU1.TGRA and MTU2.TGRA or to registers MTU1.TGRB and MTU2.TGRB, but the values of MTU1.TCNT =
FFF0h and MTU2.TCNT = 0000h are erroneously transferred.
The MTU has a function that allows simultaneous capture of counters MTU1.TCNT and MTU2.TCNT with a single
input capture input. This function can be used to read the 32-bit counter such that counters MTU1.TCNT and
MTU2.TCNT are captured at the same time. For details, refer to
section 23.2.7, Timer Input Capture Control
.