RL78/G15 CHAPTER 19 FLASH MEMORY
R01UH0959EJ0110 Rev.1.10 Page 682 of 765
Mar 7, 2023
19.7 Data Flash
19.7.1 Data flash overview
An overview of the data flash memory is provided below.
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The user program can rewrite the data flash memory by using the self-programming code.
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The data flash memory can also be rewritten to through serial programming using the dedicated flash memory
programmer or an external device.
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The data flash can be erased in 1-block (512-byte) units.
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The data flash can be accessed in 8-bit or 16-bit units.
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The data flash can be directly read by CPU instructions.
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Instructions cannot be executed from the code flash memory while rewriting the data flash memory since the CPU
is stopped during this period (that is, background operation (BGO) is not supported).
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Because the data flash memory is an area exclusively used for data, it cannot be used to execute instructions.
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The data flash memory cannot be accessed while rewriting the code flash memory since the CPU is stopped during
this period.
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The high-speed on-chip oscillator should be kept operating while rewriting the data flash memory. If it is stopped, it
should be made to operate again (HIOSTOP = 0), and the flash self-programming code should be re-executed after
30 μs have elapsed.
19.7.2 Procedure for accessing data flash memory
The data flash memory is accessible at any time after a reset ends. Reading the data flash memory by CPU instructions
does not require initial settings of the registers. For the procedure for rewriting the data flash memory, see 19.6.2
Procedure for executing self-programming of code/data flash memory.
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