ST92T163 ST Microelectronics, ST92T163 Datasheet - Page 80

• Manufacturer Part Number: ST92T163
• Description: 8/16-BIT FULL SPEED USB MCU FOR COMPOSITE DEVICES WITH 16 ENDPOINTS
• Manufacturer: ST Microelectronics

ST92163 - RESET AND CLOCK CONTROL UNIT (RCCU)
Figure 38. Example of Low Power Mode programming
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continued
Main code execution
Wait for the
PLL locking
(LOCK->1)
Interrupt
Interrupt
Routine
WAIT
WAIT
PROGRAM FLOW
CSU_CKSEL
WFI_CKSEL
User’s Program
CSU_CKSEL<- 1
CSU_CKSEL = 0
DX2-0
CKAF_SEL <- 0
User’s Program
XTSTOP
LPOWFI
XTSTOP = 0
XTSTOP
MX(1:0)
WFI status
DIV2
Begin
WFI
End
001
0
01
1
1
0
1
1
COMMENTS
Low Power Mode enabled
Multiplier divider’s factor set
To stop PLL and Xtal when
a WFI occurs
CK_AF clock selected when WFI
No code is executed until
the system clock
The system CK
switches to Xtal
to 2, and PLL turned ON
PLL is
system clock source
Interrupt served
To restart Xtal and PLL
Wait For Interrupt
an interrupt is requested
restart the PLL quickly
PLL multiply factor
while the CK_AF is
The PLL is locked
and becomes the
system clock
Quartz not divided by 2
Xtal is selected to
fixed to 6.
SET UP AFTER RESET PHASE:
** T
* T
1
2
= PLL lock-in time
= Quartz oscillator start-up time
SYSTEM CLOCK FREQUENCY
F
Q
=8 MHz, V
cc
T
T
=5 V and T=25 C
1
1
*
*
T
2
**
oscillator
oscillator
24 MHz
24 MHz
8 MHz
8 MHz
RC
RC