R28 datasheet(94/473 Pages) RENESAS

94 / 473 page

R8C/28 Group, R8C/29 Group

10. Clock Generation Circuit

Rev.2.10

Sep 26, 2008

Page 75 of 441

REJ09B0279-0210

Figure 10.3

CM1 Register

System Clock Control Register 1

(1)

Symbol

Address

After Reset

CM1

0007h

00100000b

Bit Symbol

Bit Name

Function

NOTES:

10. For J, K version, the XCIN clock oscillation circuit cannot be used. Set to 0.

Once the CM13 bit is set to 1 by a program, it cannot be set to 0.

When entering stop mode, the CM15 bit is set to 1 (drive capacity high).

Set the PRC0 bit in the PRCR register to 1 (w rite enable) before rew riting the CM1 register.

When the CM10 bit is set to 1 (stop mode) and the CM13 bit is set to 1 (XIN-XOUT pin), the XOUT (P4_7) pin goes “H”.

When the CM13 bit is set to 0 (input ports, P4_6, P4_7), P4_7 (XOUT) enters input mode.

In count source protect mode (refer to 13.2 Count Source Protection Mode Enabled), the value remains

unchanged even if bits CM10 and CM14 are set.

When the CM06 bit is set to 0 (bits CM16, CM17 enabled), bits CM16 to CM17 are enabled.

If the CM10 bit is set to 1 (stop mode), the on-chip feedback resistor is disabled.

When the OCD2 bit is set to 0 (XIN clock selected), the CM14 bit is set to 1 (low -speed on-chip oscillator stopped).

When the OCD2 bit is set to 1 (on-chip oscillator clock selected), the CM14 bit is set to 0 (low -speed on-chip

oscillator on). It remains unchanged even if 1 is w ritten to it.

When using the voltage monitor 1 interrupt or voltage monitor 2 interrupt (w hen using the digital filter), set the CM14

bit to 0 (low -speed on-chip oscillator on).

b7 b6 b5 b4 b3 b2 b1 b0

CM10

All clock stop control bit(4, 7, 8)

0 : Clock operates

1 : Stops all clocks (stop mode)

CM11

XIN-XOUT on-chip feedback resistor

select bit

0 : On-chip feedback resistor enabled

1 : On-chip feedback resistor disabled

CM12

XCIN-XCOUT on-chip feedback

resistor select bit(10)

0 : On-chip feedback resistor enabled

1 : On-chip feedback resistor disabled

CM13

Port XIN-XOUT sw itch bit(7, 9)

0 : Input ports P4_6, P4_7

1 : XIN-XOUT pin

CM14

Low -speed on-chip oscillation stop

bit(5, 6, 8)

0 : Low -speed on-chip oscillator on

1 : Low -speed on-chip oscillator off

CM15

XIN-XOUT drive capacity select bit(2)

0 : Low

1 : High

CM17

b7 b6

0 0 : No division mode

0 1 : Divide-by-2 mode

1 0 : Divide-by-4 mode

1 1 : Divide-by-16 mode

System clock division select bits 1(3)

CM16

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