Motorola ColdFire MCF5281 - Manual (Page 178)

Clock Module
9-8 Freescale Semiconductor
9.6.2.2 Synthesizer Status Register (SYNSR)
The SYNSR is a read-only register that can be read at any time. Writing to the SYNSR has no effect and
terminates the cycle normally.
7 LOCEN Enables the loss-of-clock function. LOCEN does not affect the loss of lock function.
1 Loss-of-clock function enabled
0 Loss-of-clock function disabled
Note: In external clock mode, the LOCEN bit has no effect
.
6 DISCLK Disable CLKOUT determines whether CLKOUT is driven. Setting the DISCLK bit
holds CLKOUT low.
1 CLKOUT disabled
0 CLKOUT enabled
5 FWKUP Fast wakeup determines when the system clocks are enabled during wakeup from
stop mode.
1 System clocks enabled on wakeup regardless of PLL lock status
0 System clocks enabled only when PLL is locked or operating normally
Note: When FWKUP = 0, if the PLL or oscillator is enabled and unintentionally lost in
stop mode, the PLL wakes up in self-clocked mode or reference clock mode
depending on the clock that was lost. In external clock mode, the FWKUP bit has no
effect on the wakeup sequence.
4 — Reserved, should be cleared.
3–2 STPMD Control PLL and CLKOUT operation in stop mode. The following table illustrates
STPMD operation in stop mode.
1–0 — Reserved, should be cleared.
7 6 5 4 3 2 1 0
Field PLLMODE PLLSEL PLLREF LOCKS LOCK LOCS —
Reset See note 1 See note 2 000
R/W R
Address IPSBAR + 0x0012_0002
Note: 1. Reset state determined during reset configuration.
2. See the LOCKS and LOCK bit descriptions.
Figure 9-4. Synthesizer Status Register (SYNSR)
Table 9-4. SYNCR Field Descriptions (continued)
Bit(s) Name Description
STPMD[1:0] Operation During Stop Mode
System
Clocks
PLL OSC CLKOUT
00 Disabled Enabled Enabled Enabled
01 Disabled Enabled Enabled Disabled
10 Disabled Disabled Enabled Disabled
11 Disabled Disabled Disabled Disabled
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3