HD64F2149 Datasheet, PDF (737/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

23.2.2 Low-Power Control Register (LPWRCR)
Bit
7
6
5
4
3
2
1
0
DTON LSON NESEL EXCLE —
—
—
—
Initial value
0
0
0
0
0
0
0
0
Read/Write ^R/W
R/W
R/W
R/W
R/W
—
—
—
(H8S/2169)
Read/Write ^R/W
R/W
R/W
R/W
—
—
—
—
(H8S/2149)
LPWRCR is an 8-bit readable/writable register that performs power-down mode control.
Only bit 4 is described here. For a description of the other bits, see section 24.2.2, Low-Power
Control Register (LPWRCR).
LPWRCR is initialized to H'00 by a reset and in hardware standby mode. It is not initialized in
software standby mode.
Bit 4—Subclock Input Enable (EXCLE): Controls subclock input from the EXCL pin.
Bit 4
EXCLE
0
1
Description
Subclock input from EXCL pin is disabled
Subclock input from EXCL pin is enabled
(Initial value)
23.3 Oscillator
Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock.
23.3.1 Connecting a Crystal Resonator
Circuit Configuration: A crystal resonator can be connected as shown in the example in figure
23.2. Select the damping resistance R_d according to table 23.2. An AT-cut parallel-resonance
crystal should be used.
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