SH7619 Datasheet, PDF(619/836 Page) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7619 Series

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SH7619 Datasheet, PDF (619/836 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7619 Series

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Section 19 I/O Ports

19.6 Usage Notes

1. When pins that are multiplexed with general I/O is used as output pins for other functions,

these pins work as general output pins for the period of 1 Ã tPCYC synchronized with internal

power-on reset by WDT overflow. For example, when the pin PB12/CS3 works as CS3 and

the PB12DR bit in PBDRL is set to 0, the pin is driven low for the period of 1 Ã tPCYC and may

lead to memory malfunction. To prevent this, port registers that correspond to pins used for the

strobe output must be set to strobe non-active level. This case does not apply to the power-on

reset from the RES pin.

2. The weak keeper circuit is included in all pins except MD5, MD3, MD2, MD1, MD0,

ASEMD, TESTMD, EXTAL, and XTAL. The weak keeper is a circuit that fixes the input in

I/O pins to low or high when the pins are not driven from outside. Notes on processing the

input pins are as follows:

ï£§ When using pins having the weak keeper circuit as input pins and driving these pins to a

certain level from outside, adjust the resistance of pull-up/pull-down resistors to let the

weak keeper circuit keep the intended levels. (2 kâ¦ and 8 kâ¦ are recommended

respectively.) A large resistance may fail to let the weak keeper circuit to keep the intended

levels.

ï£§ While using the pins having the weak keeper circuit as input pins, if their levels do not

matter, there is no need to deal with pins from outside.

ï£§ MD5, MD3, MD2, MD1, MD0, ASEMD, and TESTMD.

Drive these to intended levels from outside. Since the weak keeper circuit is not included in

those pins, comparatively large resistance in pull-up/pull-down resistors can be used.

ï£§ EXTAL, and XTAL

See section 8.6, Notes on Board Design in section 8, Clock Pulse Generator (CPG).

3. Since the HIFMD pin is not initially set to function as a general port pin, it must be pulled up

or down externally to fix its state.

4. When using a multiplexed pin with a function not selected with its initial value (for example,

using the PB12/CS3 pin, the initial function of which is PB12, as the CS3 pin), the pin must be

pulled up or down externally at least after a reset until its pin function is selected by software

to fix its state.

Rev. 5.00 Mar. 15, 2007 Page 581 of 794

REJ09B0237-0500

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