32186 datasheet(1019/1032 Pages) RENESAS

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SUMMARY OF PRECAUTIONS

Appendix 4

Appendix 4-29

32185/32186 Group Hardware Manual

Rev.1.10 REJ09B0235-0110 May 15, 07

Appendix 4.13 Notes on DRI

Precautions about the DRI is shown below.

• In order that the data writing from DRI and RTD to internal RAM use the exclusive bus prepared apart from M32 R-

FPU, do not usually generate the competition with access from other bus masters (CPU, DMA, NBD, SDI).

However DRI transfer, RTD transfer and the access (read-out/writing) from other bus master occur at the same

time for areas of the 16-K byte unit of internal RAM, access competition occurs.

When access competition occurs, mediation is operated according to the following priority.

NBD/SDI > DMA > CPU > DRI > RTD

Appendix 4.14 Notes on RAM Backup Mode

Appendix 4.14.1 Precautions to Be Observed at Power-On

When changing portn from input mode to output mode after power-on, pay attention to the following.

If port n is set for output mode while no data is set in the Portn Data Register, the port’s initial output level is

instable. Therefore, before changing portn for output mode, make sure the Portn Data Register is set to output a

"H."

Unless this precaution is followed, port output may go "L" at the same time the port is set for output after the

oscillation has stabilized, causing the microcomputer to enter RAM backup mode.

Appendix 4.14.2 Power-On Limitation

When powering on, make sure to meet the limitation VDDE

≥ VCCER. If VDDE is 3.0 V or more, there will be no

problem even when the limitation VDDE

≥ VCCER cannot be met.

When the above power-on limitation cannot be met, sufficient evaluation must be made during system design

in order to ensure that no power will be applied to the microcomputer with a potential difference of 1 V or more.

For potential differences 0 V to 0.6 V, there is almost no in-flow current. The amount of in-flow current begins to

increase when the potential difference exceeds 0.6 V.

32186 Datasheet(PDF) 1019 Page - Renesas Technology Corp