Toshiba TMP91C815F Data Book page 26

Limitation point on the use of DFM
It's prohibited to execute DFM enable/disable control in the SLOW mode(fs)
1.
(write to DFMCR0<ACT1:0>="10"). You should control DFM in the NORMAL mode.
2. If you stop DFM operation during using DFM (DFMCR0<ACT1:0>="10") , you shouldn't execute the
commands that change the clock f
executions should be separated into two procedures as showing below.
LD (DFMCR0),C0H
LD (DFMCR0),00H
3. If you stop high frequency oscillator during using DFM(DFMCR0<ACT1:0>="10") , you should stop DFM
before you stop high frequency oscillator.
Examples of settings are below.
(1) Start Up / Change Control
(OK) Low frequency oscillator operation mode(f
→ High frequency oscillator start up → High frequency oscillator operation mode(f
start up → DFM use mode (f
LD (SYSCR0), 11---1--B
WUP: BIT 2,(SYSCR0)
JR NZ,WUP
LD (SYSCR1), ----0---B
LD (DFMCR0),01-0----B
LUP: BIT 5, (DFMCR0)
JR NZ,LUP
LD (DFMCR0),10-0----B
(OK) Low frequency oscillator operation mode(f
→ High frequency oscillator operation mode(f
LD (SYSCR1), ----0---B
LD (DFMCR0), 01-0---B
LUP: BIT 5, (DFMCR0)
JR NZ,LUP
LD (DFMCR0),10-0----B
(NG) Low frequency oscillator operation mode(f
→ High frequency oscillator start up → DFM start up → DFM use mode (f
LD (SYSCR0),11---1--B
WUP: BIT 2,(SYSCR0)
JR NZ,WUP
LD (DFMCR0),01-0----B
LUP: BIT 5, (DFMCR0)
JR NZ,LUP
LD (DFMCR0),10-0----B
LD (SYSCR1), -----0---B
to f and stop the DFM at the same time. Therefore the above
DFM OSCH
; Change the clock f
DFM
; DFM stop
) (high frequency oscillator STOP)
s
)
DFM
; High frequency oscillator start up/ Warming up start
;
Check for the flag of warming up end
;
; Change the system clock fs to f
; DFM start up / lock up start
;
Check for the flag of lock up end
;
; Change the system clock f
) (high frequency oscillator Operate)
s
)→DFM start up → DFM use mode (f
OSCH
; Change the system clock fs to f
; DFM start up / lock up start
;
Check for the flag of lock up end
;
; Change the system clock f
) (high frequency oscillator STOP)
s
; High frequency oscillator start up/ Warming up start
;
Check for the flag of warming up end
;
; DFM start up / lock up start
;
Check for the flag of lock up end
;
; Change the internal clock f
; Change the system clock fs to f
91C815-23
TMP91C815
to f
OSCH
OSCH
OSCH
to f
OSCH DFM
OSCH
to f
OSCH DFM
)
DFM
to f
OSCH DFM
DFM
)→DFM
)
DFM