ST72324J6B5 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
ST72324J6B5
STMicroelectronics
ST72324J6B5 Datasheet PDF : 161 Pages
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ST72324
10.2 MAIN CLOCK CONTROLLER WITH REAL TIME CLOCK AND BEEPER (MCC/RTC)
The Main Clock Controller consists of three differ-
ent functions:
s a programmable CPU clock prescaler
s a clock-out signal to supply external devices
s a real time clock timer with interrupt capability
Each function can be used independently and si-
multaneously.
10.2.1 Programmable CPU Clock Prescaler
The programmable CPU clock prescaler supplies
the clock for the ST7 CPU and its internal periph-
erals. It manages SLOW power saving mode (See
Section 8.2 SLOW MODE for more details).
The prescaler selects the fCPU main clock frequen-
cy and is controlled by three bits in the MCCSR
register: CP[1:0] and SMS.
10.2.2 Clock-out Capability
The clock-out capability is an alternate function of
an I/O port pin that outputs a fOSC2 clock to drive
external devices. It is controlled by the MCO bit in
the MCCSR register.
CAUTION: When selected, the clock out pin sus-
pends the clock during ACTIVE-HALT mode.
10.2.3 Real Time Clock Timer (RTC)
The counter of the real time clock timer allows an
interrupt to be generated based on an accurate
real time clock. Four different time bases depend-
ing directly on fOSC2 are available. The whole
functionality is controlled by four bits of the MCC-
SR register: TB[1:0], OIE and OIF.
When the RTC interrupt is enabled (OIE bit set),
the ST7 enters ACTIVE-HALT mode when the
HALT instruction is executed. See Section 8.4 AC-
TIVE-HALT AND HALT MODES for more details.
10.2.4 Beeper
The beep function is controlled by the MCCBCR
register. It can output three selectable frequencies
on the BEEP pin (I/O port alternate function).
Figure 35. Main Clock Controller (MCC/RTC) Block Diagram
MCCBCR
BC1 BC0
BEEP SIGNAL
SELECTION
BEEP
MCO
fOSC2
DIV 64
12-BIT MCC RTC
COUNTER
TO
WATCHDOG
TIMER
MCO CP1 CP0 SMS TB1 TB0 OIE OIF
MCCSR
DIV 2, 4, 8, 16
1
0
MCC/RTC INTERRUPT
fCPU
CPU CLOCK
TO CPU AND
PERIPHERALS
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