Application Note
R01AN5679EJ0110 Rev.1.10 Page 1 of 74
July.16.21
RX23E-A Group
Channel-to-channel isolated analog measurement system
Introduction
This document describes a system which has 4 pieces of Renesas microcontroller RX23E-A measuring
temperature or voltage synchronously with channel-to-channel isolation. RX23E-A in each unit samples
output voltage of thermocouple/RTD or pin input voltage with built-in 24-bit Δ-ΣA/D converter (DSAD) in
cycle of approximate 1 msec, performs filter processing, and converts to temperature or voltage.
As an upper layer MCU, RX72M obtains temperature or voltage measured in each unit in cycles of 10 ms
and transmits to PC via USB. As a result, 4-channel synchronous measurement can be realized within 1 ms.
Communication between 4 pieces of RX23E-A and RX72M is performed by a single channel 3-wire serial
communication, and individual communications with the specified unit address and the broadcast
communication are performed. This can reduce isolators comparing to 4-wire SPI communication which uses
chip select.
Target Application:
Analog input module
Temperature controller
Recorder
DC/DC
Converter
ISL80015
3-wire
SPI
Multi-Channel Measurement Board
TS-RX72M-COM
3-wire SPI bus
RX23E-A
1 Unit
RX72M
USB
PC tool
Program
22～36V
DC/DC
Converter
ISL85410
RV1S9260A
RV1S9260A
PS9124
LDO
ISL80410
VCC_A
AVCC0_A
VSS_A
VSS_B
VCC_BAVCC0_B
Thermocouple
or
Voltage Source
5V
6~7V
6~7V
5V
5V
3.3V
Communication Board
Enable
U8
U1
T1
PC101～PC103
Photocouplers
U101
U102
RTD101
U201
DC/DC
Converter
ISL85410
FB
GND1
GND1
FB
GND1
DC/DC
Converter
ISL85410
U2
Isolated Buck
Converter
U3
Isolated Buck
Converter
U1
Buck Converter
Turn Ratio1:1
LDO
ISL80410
LDO
ISL80410
VSS_C
VSS_D
3-wire
SPI
RX23E-A
1 Unit
RV1S9260A
RV1S9260A
PS9124
VCC_DAVCC0_D
Thermocouple
or
Voltage Source
6~7V
6~7V
5V
T2
PC401～PC403
Photocouplers
U301
U401
RTD401
U402
GND1
Turn Ratio1:1
LDO
ISL80410
VCC_C
AVCC0_C
5V
Channel A
Channel B
Channel C
Channel D
A
D
Appearance and Block Diagram of Channel-to-Channel Isolated Analog Measurement System
Target Device
RX23E-A (R5F523E6SDNF)
RX72M (R5F572MNDDBD)
RX23E-A Group Channel-to-channel isolated analog measurement system
R01AN5679EJ0110 Rev.1.10 Page 2 of 74
July.16.21
Contents
1. Overview ................................................................................................................................. 4
1.1 Function / Specification ........................................................................................................................... 4
1.2 Introduction of Renesas Electronics' Products ........................................................................................ 5
2. Related Documents ................................................................................................................. 6
3. Environment for Operation Confirmation .................................................................................. 7
4. System Configuration .............................................................................................................. 8
5. Hardware Configuration ......................................................................................................... 10
5.1 Communication Board ........................................................................................................................... 10
5.2 Multi-Channel Measurement Board ....................................................................................................... 10
5.2.1 Descriptions of Circuits ........................................................................................................................ 10
6. Measurement Process ........................................................................................................... 14
6.1 Temperature Measurement ................................................................................................................... 14
6.1.1 A/D Conversion of Thermocouple and RTD ........................................................................................ 14
6.1.2 Filter Processing .................................................................................................................................. 15
6.1.2.1 Moving Average Filter ....................................................................................................................... 16
6.1.2.2 Band Elimination Filter and Lowpass Filter ....................................................................................... 16
6.1.3 Temperature Calculation ..................................................................................................................... 17
6.2 Voltage Measurement ........................................................................................................................... 17
6.2.1 A/D Conversion of Input Voltage ......................................................................................................... 17
6.2.2 Moving Average Filter ......................................................................................................................... 18
6.2.3 Voltage Calculation ............................................................................................................................. 18
7. Sample Program .................................................................................................................... 19
7.1 Communication Specification ................................................................................................................ 19
7.1.1 Communication between Host and Measurement Unit ....................................................................... 19
7.1.1.1 SPI Communication Specification ..................................................................................................... 19
7.1.1.2 Communication Sequence ................................................................................................................ 20
7.1.1.3 Packet Structure ................................................................................................................................ 21
7.1.1.4 Command .......................................................................................................................................... 22
7.1.2 Communication between PC Tool and Host ....................................................................................... 23
7.2 Measurement Processing (RX23E-A) ................................................................................................... 24
7.2.1 Operation Overview ............................................................................................................................. 24
7.2.2 Peripheral Functions and Pins Used ................................................................................................... 26
7.2.2.1 AFE・DSAD0 .................................................................................................................................... 27
7.2.2.2 RSPI0・DMAC0・DMAC1・P17 ..................................................................................................... 29
7.2.2.3 P30・P31 .......................................................................................................................................... 31
7.2.3 Communication Process ..................................................................................................................... 32