RX62T

Position Control of PMSM with Encoder

R01AN0899EU0200 Rev. 2.00

Page 5 of 22

Jan. 31, 2014

4. RX62T Encoder Capture Function

The RX62T is a 32-bit high-performance microcontroller with a maximum operating frequency of 100MHz and 165

DMIPS and single precision floating-point unit (FPU), which is equipped with multifunction timers (

H

MTU

H

,

H

GPT

H

), high-

speed

H

12-bit A/D converter

H

, and 10-bit A/D converter for facilitating motor control. Figure 2 shows the block diagram of

a senorless vector control of PMSM based on the Renesas RX62T Microcontroller.

RX62T has a dedicate function for the encoder measurement as depicted in Figure 2. MTU3 timer external clock input

TCLKA, TCLKB, TCLKC, and TCLKD can be used for two-phase encoder pulse inputs. When the MTU3 timer of

Channels 1 and 2 are specified by the phase counting mode, an external encoder clock is selected as the counter input

clock and TCNT operates as an up/down-counter. The phase difference between two external input clocks is detected and

TCNT is incremented or decremented accordingly. The rotor position and speed can be measured by reading the TCNT

counts.

The following summarizes the MTU3 function for the encoder pulse counting functionality:

 MTU Channel 1 & 2 support 2-phase pulse counting mode which is called “Phase Counting Mode”

 This function covers 4 modes

 At these modes, the counter works as up/down counter. And it is possible to detect the direction of counter with

the flag.

 Up/down count by detecting phase difference between phase A and B of encoder on mode1 and mode 4

o

Mode 1: every rising edge & falling edge of both of encoder pulse

o

Mode 4: every rising edge & falling edge of phase B encoder pluses

 Up/down count by two pulse lines which indicate the direction, speed and position.

o

Mode 2: One pulse line and One direction

o

Mode 3: Two pulse lines for each direction

 MTU can detect automatically speed and position data as the pulse width & the pulse. The data of speed and

position can be captured every periodic cycle.

In this application, the encoder pulse A and B are input to the TCLKA and TCLKB. The Z pulse is to IRQ0. For the

second motor, the encoder pulse A and B are input to the TCLKC and TCLKD. The Z pulse is to IRQ3.

The host communication using the graphic user interface (GUI) is communicated with the RX62T MCU by the USB

communication. It can display the motor operation status in the real time, tune the motor and control parameters, and

drive the motor for both speed control and position control.

Figure 2 RX62T encoder capture functionality