ST72324K4 STMicroelectronics, ST72324K4 Datasheet - Page 86

• Manufacturer Part Number: ST72324K4
• Description: 8-BIT MCU WITH NESTED INTERRUPTS, FLASH, 10-BIT ADC, 4 TIMERS, SPI, SCI INTERFACE
• Manufacturer: STMicroelectronics

Specifications of ST72324K4

• Hdflash Endurance: 100 cycles, data retention
• Clock Sources: crystal/ceramic resonator oscillators, internal RC oscillator, clock security system and bypass for external clock
• Four Power Saving Modes: Halt, Active-Halt, Wait and Slow
• Main Clock Controller With: Real time base, Beep and Clock-out capabilities
• 16-bit Timer A With: 1 input capture, 1 output compare, external clock input, PWM and pulse generator modes
• 16-bit Timer B With: 2 input captures, 2 output compares, PWM and pulse generator modes

ST72324Jx ST72324Kx
SERIAL PERIPHERAL INTERFACE (Cont’d)
10.4.6 Low Power Modes
10.4.6.1 Using the SPI to wakeup the MCU from
Halt mode
In slave configuration, the SPI is able to wakeup
the ST7 device from HALT mode through a SPIF
interrupt. The data received is subsequently read
from the SPIDR register when the software is run-
ning (interrupt vector fetch). If multiple data trans-
fers have been performed before software clears
the SPIF bit, then the OVR bit is set by hardware.
86/164
1
WAIT
HALT
Mode
No effect on SPI.
SPI interrupt events cause the device to exit
from WAIT mode.
SPI registers are frozen.
In HALT mode, the SPI is inactive. SPI oper-
ation resumes when the MCU is woken up by
an interrupt with “exit from HALT mode” ca-
pability. The data received is subsequently
read from the SPIDR register when the soft-
ware is running (interrupt vector fetching). If
several data are received before the wake-
up event, then an overrun error is generated.
This error can be detected after the fetch of
the interrupt routine that woke up the device.
Description
Note: When waking up from Halt mode, if the SPI
remains in Slave mode, it is recommended to per-
form an extra communications cycle to bring the
SPI from Halt mode state to normal state. If the
SPI exits from Slave mode, it returns to normal
state immediately.
Caution: The SPI can wake up the ST7 from Halt
mode only if the Slave Select signal (external SS
pin or the SSI bit in the SPICSR register) is low
when the ST7 enters Halt mode. So if Slave selec-
tion is configured as external (see
10.4.3.2), make sure the master drives a low level
on the SS pin when the slave enters Halt mode.
10.4.7 Interrupts
Note: The SPI interrupt events are connected to
the same interrupt vector (see Interrupts chapter).
They generate an interrupt if the corresponding
Enable Control Bit is set and the interrupt mask in
SPI End of Transfer
Event
Master Mode Fault
Event
Overrun Error
Interrupt Event
MODF
Event
SPIF
OVR
Flag
Control
Enable
SPIE
Bit
from
Wait
Exit
Yes
Yes
Yes
Section
from
Halt
Exit
Yes
No
No