Application Note
R01AN4865EJ0100 Rev.1.00 Page 1 of 84
Oct.31.19
RX23E-A Group, RX21A Group
Differences Between the RX23E-A Group and the RX21A Group
Summary
This application note is intended as a reference to points of difference between the peripheral functions, I/O
registers, and pin functions of the RX23E-A Group and RX21A Group, as well as a guide to key points to
consider when migrating between the two groups.
Unless specifically otherwise noted, the information in this application note applies to the 48-pin package
version of the RX23E-A Group and the 100-pin package version of the RX21A Group. To confirm details of
differences in the specifications of the electrical characteristics, usage notes, and setting procedures, refer to
the User’s Manual: Hardware of the products in question.
Target Devices
RX23E-A Group and RX21A Group
Contents
1. Comparison of Built-In Functions of RX23E-A Group and RX21A Group ................................. 3
2. Comparative Overview of Specifications ................................................................................... 5
2.1 CPU ......................................................................................................................................................... 5
2.2 Operating Modes ..................................................................................................................................... 6
2.3 Address space ......................................................................................................................................... 7
2.4 Resets ..................................................................................................................................................... 8
2.5 Option-Setting Memory ........................................................................................................................... 9
2.6 Voltage Detection Circuit ....................................................................................................................... 10
2.7 Clock Generation Circuit ....................................................................................................................... 20
2.8 Clock Frequency Accuracy Measurement Circuit ................................................................................. 23
2.9 Low Power Consumption ...................................................................................................................... 25
2.10 Register Write Protection Function........................................................................................................ 30
2.11 Exception Handling ............................................................................................................................... 31
2.12 Interrupt Controller ................................................................................................................................ 32
2.13 Buses ..................................................................................................................................................... 34
2.14 Memory-Protection Unit ......................................................................................................................... 36
2.15 Event Link Controller ............................................................................................................................. 37
2.16 I/O Ports ................................................................................................................................................ 42
2.17 Multi-Function Pin Controller ................................................................................................................. 44
2.18 Compare Match Timer ........................................................................................................................... 45
2.19 Independent Watchdog Timer ............................................................................................................... 46
2.20 Serial Communications Interface .......................................................................................................... 48
2.21 I
2
C Bus Interface ................................................................................................................................... 53
2.22 Serial Peripheral Interface ..................................................................................................................... 56
RX23E-A Group, RX21A Group Differences Between the RX23E-A Group and the RX21A Group
R01AN4865EJ0100 Rev.1.00 Page 2 of 84
Oct.31.19
2.23 24-Bit ∆Σ A/D Converter ........................................................................................................................ 59
2.24 10-Bit A/D Converter/12-Bit A/D Converter ........................................................................................... 63
2.25 Data Operation Circuit ........................................................................................................................... 69
2.26 RAM ....................................................................................................................................................... 70
2.27 Flash Memory ........................................................................................................................................ 71
2.28 Packages ............................................................................................................................................... 75
3. Comparison of Pin Functions .................................................................................................. 76
3.1 64-Pin Package (RX21A: LQFP)/48-Pin Package (RX23E-A: LQFP)/
40-Pin Package (RX23E-A: HWQFN) ................................................................................................... 76
4. Important Information when Migrating Between MCUs ........................................................... 80
4.1 Notes on Pin Design .............................................................................................................................. 80
4.1.1 VCL Pin (External Capacitor) .............................................................................................................. 80
4.1.2 Mode Setting Pins ............................................................................................................................... 80
4.2 Notes on Functional Design .................................................................................................................. 80
4.2.1 MOSCWTCR Register ........................................................................................................................ 80
4.2.2 Limitations Applying to I/O Port Register Settings .............................................................................. 80
4.2.3 Exception Vector Table ....................................................................................................................... 80
4.2.4 I
2
C Bus Interface Noise Cancellation .................................................................................................. 80
4.2.5 24-Bit ΔΣ A/D Converter ...................................................................................................................... 80
4.2.6 Compare Function Limitations............................................................................................................. 80
4.2.7 User Boot Mode .................................................................................................................................. 81
4.2.8 Using Flash Memory Programming Commands ................................................................................. 81
5. Reference Documents ............................................................................................................. 82
Revision History .............................................................................................................................. 84