3886 datasheet(293/380 Pages) RENESAS

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2-176

3886 Group User’s Manual

APPLICATION

2.15 Flash memory

2.15.8 Notes on CPU reprogramming mode

(1)

Transfer the CPU reprogramming mode control program to the internal RAM before selecting the

CPU reprogramming mode, and then, execute it on the internal RAM. Additionally, when the subroutine

or stack operation instruction is used in the control program, make sure the control program is not

destroyed by the stack operation.

(2)

Make sure each instruction description (specified address etc.) is correct, because the CPU reprogramming

mode control program is transferred to the internal RAM and executed on the internal RAM.

(3)

In order to avoid generation of a watchdog timer reset, write to the watchdog timer control register

periodically during the CPU reprogramming mode control program (refer to “2.7 Watchdog timer”).

(4)

Notes on flash memory version

The CNVSS pin is connected to the internal memory circuit block by a low-ohmic resistance, since it

works as a program power source pin (VPP pin), as well.

To improve the noise margin, connect the CNVSS pin to VSS through 1 to 10 k

Ω resistor.

When the CNVSS pin of the mask ROM version is connected to Vss through this resistor, the function

of mask ROM version works well in the same manner as flash memory version.

3886 Datasheet(PDF) 293 Page - Renesas Technology Corp