APPENDIX B POWER SAVING
AP-B-2
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
Clock
Clock enable bit
Peripheral modules
PCLK2
PCLK2_EN/CMU_CLKCTL register
• Prescaler (PSC Ch.1)
• 8-bit programmable timer Ch.1, 3, 5, 7 (T8 Ch.1, 3, 5, 7)
• Universal serial interface with LCD interface (USIL)
• Serial interface Ch.1 (FSIO Ch.1)
• Watchdog timer (WDT)
• Remote controller (REMC)
• Interrupt controller (ITC)
• I/O ports (GPIO)
• BBRAM
• Cache controller (CCU) registers
• Real-time clock (RTC) registers
• SRAM controller (SRAMC) registers
• SDRAM controller (SDRAMC) registers
• LCD controller (LCDC) registers
GCLK
GCLK_EN/CMU_CLKCTL register
Graphics engine (GE)
LCLK
LCLK_EN/CMU_CLKCTL register
LCD controller (LCDC)
USBCLK
USBCLK_EN/CMU_CLKCTL register
USB function controller (USB)
USBREGCLK USBREGCLK_EN/CMU_CLKCTL register USB function controller (USB) registers
SDCLK
SDCLK_EN/CMU_CLKCTL register
• SRAM controller (SRAMC)
• SDRAM controller (SDRAMC)
BCLK
BCLK_EN/CMU_CLKCTL register
• IVRAM (Area 3)
• DSTRAM (Area 3)
• SRAM controller (SRAMC)
• SDRAM controller (SDRAMC)
• DMA controller (DMAC)
• LCD controller (LCDC) bus interface
• Clock management unit (CMU) registers
• Bus arbiters
(Can be stopped in HALT mode.)
Table B.2 lists the clock control conditions and how to suspend/resume the CPU operation.
2 List of Clock Control Conditions
Table B.
Current con-
sumption
OSC1
OSC3/PLL
CPU
(CCLK)
Peripherals
CPU suspending
method
CPU resuming
method
↑
Low
Oscillating
Stop
Stop
Stop
slp instruction
1
Oscillating
Stop
Stop
Stop (only RTC is
running)
slp instruction
1, 2
Oscillating
(System clock)
Stop
Stop
Stop (only RTC is
running)
halt instruction
1, 2
Oscillating
(System clock)
Stop
Stop
Run
halt instruction
1, 2, 3
Oscillating
(System clock)
Stop
Run
Run
Stop
Oscillating
(System clock)
Stop
Run
halt instruction
1, 3
Oscillating
Oscillating
(System clock)
Stop
Run
halt instruction
1, 2, 3
Stop
Oscillating
(System clock)
Run (with low-
speed clock)
Run
Oscillating
Oscillating
(System clock)
Run (with low-
speed clock)
Run
High
↓
Oscillating
Oscillating
(System clock)
Run (OSC3•1/1)
Run (PLL•1/1)
Run
Clearing HALT and SLEEP modes (CPU resuming methods)
1. Resuming by a port input interrupt, #RESET or #NMI
The CPU resumes operating by occurrence of a cause of port input interrupt, #RESET, or #NMI.
2. Resuming by the RTC
The CPU resumes operating by occurrence of a cause of RTC interrupt.