st92f124 STMicroelectronics, st92f124 Datasheet - Page 131

• Manufacturer Part Number: st92f124
• Description: 8/16-bit Single Voltage Flash Mcu Family With Ram, E3 Tmemulated Eeprom, Can 2.0b And J1850 Blpd
• Manufacturer: STMicroelectronics

Figure 63. Example of Low Power mode programming in WFI using CK_AF external clock
Interrupt
ST92F124/F150/F250 - RESET AND CLOCK CONTROL UNIT (RCCU)
CKAF_SEL
CSU_CKSEL
Interrupt Routine
CSU_CKSEL
PROGRAM FLOW
WFI_CKSEL
User’s Program
User’s Program
WFI instruction
XTSTOP
LPOWFI
XTSTOP
MX[1:0]
DX[2:0]
WFI status
WAIT
WAIT
WAIT
Begin
000
1
00
0
0
1
1
1
1
CK_AF selected and Xtal stopped
Wait for the Xtal
PLL is System Clock source
PLL is system clock source
Low Power Mode enabled
to 1, and PLL turned ON
No code is executed until
an interrupt is requested
Wait for the PLL to lock
Preselect Xtal stopped
Wait for the PLL to lock
Execution of user program
when CK_AF selected
CK_AF clock selected
The System Clock
and the Xtal restarts
resumes at full speed
PLL multiply factor
Interrupt serviced
the System Clock
switches to Xtal
Wait For Interrupt
Divider factor set
while CK_AF is
in WFI state
in WFI state
Reset State
automatically
set to 10
activated
to stabilise
** T
* T
1
2
= PLL lock-in time
= Quartz oscillator start-up time
F
T
Xtal
INTCLK FREQUENCY
T
2
1
**
= 4 MHz
*
20 MHz
2 MHz
20 MHz
2 MHz
F
CK_AF
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