RL78/G15 CHAPTER 19 FLASH MEMORY
R01UH0959EJ0110 Rev.1.10 Page 666 of 765
Mar 7, 2023
19.4.2 Flash memory programming mode
To rewrite the contents of the code flash memory by serial programming, the flash memory programming mode must be
entered.
<Serial programming using the dedicated flash memory programmer>
Connect the RL78 microcontroller to a dedicated flash memory programmer. Communication from the dedicated flash
memory programmer is performed to automatically switch to the flash memory programming mode. The operating
voltage during the flash memory programming mode is 2.4 V to 5.5 V.
<Serial programming using an external device (UART communication)>
Set the TOOL0 pin to the low level, and then cancel the reset (see Table 19-5). After that, enter flash memory
programming mode according to the procedures <1> to <4> shown in Figure 19-7.
The operating voltage during the flash memory programming mode is 2.4 V to 5.5 V.
Table 19-5. Relationship between TOOL0 Pin and Operation Mode after Reset Release
TOOL0 Operation Mode
V
DD
Normal operation mode
0 V Flash memory programming mode
Figure 19-7. Setting of Flash Memory Programming Mode
<1>
<
2
>
<3>
<
4
>
______
RESET
TOOL0
t
SU
t
SUINIT
t
HD
1-byte data for setting mode
• •
•
•
<1> The low level is input to the TOOL0 pin.
<2> The external reset ends (SPOR reset must end before the external reset ends.).
<3> The TOOL0 pin is set to the high level.
<4> Setting of entry to the flash memory programming mode by UART reception.
Remark t
SUINIT
: The segment shows that it is necessary to finish specifying the initial communication settings within
100 ms from when the resets end.
t
SU
: How long from when the TOOL0 pin is placed at the low level until an external reset ends
t
HD
: How long to keep the TOOL0 pin at the low level from when the external reset ends
For details, see 23.10 Timing of Entry to Flash Memory Programming Mode and 24.10 Timing of Entry to Flash
Memory Programming Mode.
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