RL78/G1H CHAPTER 27 FLASH MEMORY
R01UH0575EJ0120 Rev. 1.20 Page 825 of 920
Dec 22, 2016
27.7 Data Flash
27.7.1 Data flash overview
An overview of the data flash memory is provided below.
• The user program can rewrite the data flash memory by using the flash data library. For details, refer to RL78
Family Data Flash Library User’s Manual.
• The data flash memory can also be rewritten to through serial programming using the dedicated flash memory
programmer or an external device.
• The data flash can be erased in 1-block (1 KB) units.
• The data flash can be accessed only in 8-bit units.
• The data flash can be directly read by CPU instructions.
• Instructions can be executed from the code flash memory while rewriting the data flash memory (that is,
background operation (BGO) is supported).
• Because the data flash memory is an area exclusively used for data, it cannot be used to execute instructions.
• Accessing the data flash memory is not possible while rewriting the code flash memory (during self-
programming).
• Manipulating the DFLCTL register is not possible while rewriting the data flash memory.
• Transition to the STOP mode is not possible while rewriting the data flash memory.
Caution 1. The data flash memory is stopped after a reset is canceled. The data flash control register
(DFLCTL) must be set up in order to use the data flash memory.
Caution 2. The high-speed on-chip oscillator should be kept operating during data flash rewrite. If it is
kept stopped, it should be operated (HIOSTOP = 0). The flash self-programming library should
be executed after 30 μs have elapsed.
Remark Refer to flash programming mode, see 27.5 Self-Programming.
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