RX62T

Position Control of PMSM with Encoder

R01AN0899EU0200 Rev. 2.00

Page 6 of 22

Jan. 31, 2014

Table 1 lists the timer register function for Channel 0 to 2 for the encoder capture. The timer MTU enable to

automatically detect both the pulse width and the number of pulse of encoder every speed control loop period. It is not

necessary of external wiring for any trigger signals. The encoder signals are directly input to Timer external clock;

TCLKA and TCLKB as clock source of channel, and also, input command pulse to Timer external clock; TCLKC and

TCLKD as clock source of Channel 2.

 Channel 1 counter is counted by every falling edge and rising edge of encoder pulse.

 Channel 0 is used for interval time to generate input capture trigger of Channel 1 and Channel 2, and interrupt of

speed control loop.

 Channel 2 measures pulse command input.

 Channel 0 compare match (speed control loop period) can be selected as input capture trigger for Channel 1

internally.

 Channel 1 and Channel 2 external timer clock (encoder pulse or command pulse) can be selected as input

capture trigger for Channel 0 internally.

Table 1 MTU timer registers function

Figure 3 shows how the MTU captures the encoder signals in phase counting mode. The Channel 1 is coupled with

Channel 0 to input 2-phase encoder pulses of a servo motor in order to detect position or speed. Channel 1 is set to phase

counting mode 1, and the encoder pulse A-phase and B-phase are input to MTCLKA and MTCLKB. In Channel 0,

MTU3_0.TGRC compare match is specified as the TCNT clearing source and MTU3_0.TGRA and MTU3_0.TGRC are

used for the compare match function and are set with the speed control cycle and position control cycle. MTU3_0.TGRB

is used for input capture, with MTU3_0.TGRB and MTU3_0.TGRD operating in buffer mode. The Channel 1 counter

input clock is designated as the MTU3_0.TGRB input capture source, and the widths of 2-phase encoder 4-multiplication

pulses are detected. MTU3_1.TGRA and MTU3_1.TGRB for Channel 1 are designated for the input capture function

and MTU3_0.TGRA and MTU3_0.TGRC compare matches in Channel 0 are selected as the input capture sources to

store the up/down-counter values for the control cycles.

Therefore, the RX62T MTU itself can realize precise detection of the pulse width and the number of pulses,

which are needed to estimate motor speed and position. It doesn’t need the load of the CPU hardly to detect

those. Also the MTU is able to receive the pulse command as well.