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38C3 Group User’s Manual

3-29

APPENDIX

3.3 Notes on use

3.3.3 Notes on serial I/O

(1)

Selecting external synchronous clock

When an external synchronous clock is selected, the contents of serial I/O register are being shifted

continually while the transfer clock is input to the serial I/O1 clock pin. In this case, control the clock

externally.

(2)

Transmission data writing

When an external clock is used as the synchronous clock, write the transmit data to the serial I/O

shift register at “H” level of transfer clock input.

3.3.4 Notes on LCD controller

qWhen switching from the high-speed or middle-speed mode to the low-speed mode, switch the mode in

the following order:

(1) 32 kHz oscillation selected (bit 4 of CPU mode register (address 003B16) = “1”)

(2) Count source for LCDCK = f(XCIN)/32 (bit 7 of LCD mode register (address 003916) = “0”)

(3) Internal system clock: XCIN-XCOUT selected (bit 7 of CPU mode register (address 003B16) = “1”)

(4) Main clock XIN–XOUT stopped (bit 5 of CPU mode register (address 003B16) = “1”)

Execute the setting (2) after the oscillation at 32 kHz (setting (1)) becomes completely stable.

qIf the STP instruction is executed while the LCD is turned on by setting bit 3 of the LCD mode register

(address 003916) to “1”, a DC voltage is applied to the LCD. For this reason, do not execute the STP

instruction while the LCD is lighting.

qWhen the LCD is not used, open the segment and the common pins.

Connect VL1 to VL3 to VSS.

qFor the following products, if the LCD enable bit of the LCD mode register (bit 3 of address 003916) is

set to “0”, all LCDs cannot be turned off. When all LCDs are turned off, set “0” (turn off) to all corresponding

LCD display RAM.

Corresponding products: M38C34M6AXXXFP, M38C34M6MXXXFP, M38C37ECAXXXFP,

M38C37ECMXXXFP, M38C37ECAFP, M38C37ECMFP, M38C37ECAFS,

M38C3ECMFS, M38C37RFS, M38C37RMFS

38C3 Datasheet(PDF) 174 Page - Renesas Technology Corp