ST7263BHX_09 Datasheet, PDF (41/186 Pages) STMicroelectronics – Low speed USB 8-bit MCU family with up to 32 KB Flash/ROM, DFU capability, 8-bit ADC, WDG, timer, SCI and I²C

ST7263Bxx
Figure 20. Halt mode flowchart
HALT INSTRUCTION
OSCILLATOR
PERIPH. CLOCK
CPU CLOCK
I-BIT
OFF
OFF
OFF
CLEARED
Power saving modes
8.3
8.4
N
N
EXTERNAL
INTERRUPT*
RESET
Y
Y
OSCILLATOR
PERIPH. CLOCK
CPU CLOCK
I-BIT
ON
ON
ON
SET
4096 CPU CLOCK
CYCLES DELAY
FETCH RESET VECTOR
OR SERVICE INTERRUPT
1. Before servicing an interrupt, the CC register is pushed on the stack. The I-Bit is set during the interrupt
routine and cleared when the CC register is popped.
Slow mode
In Slow mode, the oscillator frequency can be divided by 2 as selected by the SMS bit in the
Miscellaneous register. The CPU and peripherals are clocked at this lower frequency. Slow
mode is used to reduce power consumption, and enables the user to adapt the clock
frequency to the available supply voltage.
Wait mode
Wait mode places the MCU in a low power consumption mode by stopping the CPU.
This power saving mode is selected by calling the “WFI” ST7 software instruction.
All peripherals remain active. During Wait mode, the I bit of the CC register is forced to 0 to
enable all interrupts. All other registers and memory remain unchanged. The MCU remains
in Wait mode until an interrupt or Reset occurs, whereupon the Program Counter branches
to the starting address of the interrupt or Reset service routine.
Doc ID 7516 Rev 8
41/186