Users Manual

Table Of Contents
R01UH0823EJ0110 Rev.1.10 Page 1760 of 1852
Nov 30, 2020
RX23W Group 50. Flash Memory (FLASH)
50.14 Usage Notes in Boot Mode
(1) Notes on Communication Errors in Boot Mode
When communication with the MCU cannot be performed properly, reset and start up in boot mode again.
(2) Notes on Power Supply Voltage in Boot Mode (SCI Interface)
When the bit rate exceeds 500 kbps in boot mode (SCI Interface), use a voltage that is 3.0 V or higher.
(3) Notes on Option-Setting Memory in Boot Mode
The settings of option function select register 0 (OFS0), option function select register 1 (OFS1), and endian select
register (MDE) are disabled in boot mode.
(4) Notes on Clocks in Boot Mode (USB Interface)
When USB interface mode is selected, externally input a clock to the EXTAL or XTAL pin, or connect a crystal or
ceramic resonator to supply a clock.
Use a 4, 6, 8, 12, or 16 MHz external clock in boot mode (USB interface). An clock other than a 4, 6, 8, 12, or
16 MHz external clock cannot be used.
(5) Notes on Power Supply Voltage in Boot Mode (USB Interface)
Use a voltage between 3.0 V and 3.6 V in boot mode (USB interface). A voltage that is lower than 3.0 V cannot be
used.
(6) Notes on Switching the Start-Up Area
Switch the start-up area by self-programming.