MSP430F643 Datasheet, PDF (20/106 Pages) Texas Instruments – MIXED SIGNAL MICROCONTROLLER

MSP430F643x
SLAS720B – AUGUST 2010 – REVISED AUGUST 2012
PIN
P2.6/P2MAP6/R03
P2.7/P2MAP7/LCDREF/R13
Table 12. Default Mapping (continued)
PxMAPy
MNEMONIC
PM_NONE
PM_NONE
INPUT PIN FUNCTION
-
-
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OUTPUT PIN FUNCTION
DVSS
DVSS
Oscillator and System Clock
The clock system in the MSP430F643x family of devices is supported by the Unified Clock System (UCS)
module that includes support for a 32-kHz watch crystal oscillator (in XT1 LF mode; XT1 HF mode is not
supported), an internal very-low-power low-frequency oscillator (VLO), an internal trimmed low-frequency
oscillator (REFO), an integrated internal digitally controlled oscillator (DCO), and a high-frequency crystal
oscillator XT2. The UCS module is designed to meet the requirements of both low system cost and low power
consumption. The UCS module features digital frequency locked loop (FLL) hardware that, in conjunction with a
digital modulator, stabilizes the DCO frequency to a programmable multiple of the watch crystal frequency. The
internal DCO provides a fast turn-on clock source and stabilizes in 3 µs (typical). The UCS module provides the
following clock signals:
• Auxiliary clock (ACLK), sourced from a 32-kHz watch crystal (XT1), a high-frequency crystal (XT2), the
internal low-frequency oscillator (VLO), the trimmed low-frequency oscillator (REFO), or the internal digitally-
controlled oscillator DCO.
• Main clock (MCLK), the system clock used by the CPU. MCLK can be sourced by same sources available to
ACLK.
• Sub-Main clock (SMCLK), the subsystem clock used by the peripheral modules. SMCLK can be sourced by
same sources available to ACLK.
• ACLK/n, the buffered output of ACLK, ACLK/2, ACLK/4, ACLK/8, ACLK/16, ACLK/32.
Power Management Module (PMM)
The PMM includes an integrated voltage regulator that supplies the core voltage to the device and contains
programmable output levels to provide for power optimization. The PMM also includes supply voltage supervisor
(SVS) and supply voltage monitoring (SVM) circuitry, as well as brownout protection. The brownout circuit is
implemented to provide the proper internal reset signal to the device during power-on and power-off. The SVS
and SVM circuitry detects if the supply voltage drops below a user-selectable level and supports both supply
voltage supervision (the device is automatically reset) and supply voltage monitoring (the device is not
automatically reset). SVS and SVM circuitry is available on the primary supply and core supply.
Hardware Multiplier
The multiplication operation is supported by a dedicated peripheral module. The module performs operations with
32-bit, 24-bit, 16-bit, and 8-bit operands. The module is capable of supporting signed and unsigned multiplication
as well as signed and unsigned multiply and accumulate operations.
Real-Time Clock (RTC_B)
The RTC_B module can be configured for real-time clock (RTC) or calendar mode providing seconds, minutes,
hours, day of week, day of month, month, and year. Calendar mode integrates an internal calendar which
compensates for months with less than 31 days and includes leap year correction. The RTC_B also supports
flexible alarm functions and offset-calibration hardware. The implementation on this device supports operation in
LPM3.5 mode and operation from a backup supply.
Watchdog Timer (WDT_A)
The primary function of the watchdog timer (WDT_A) module is to perform a controlled system restart after a
software problem occurs. If the selected time interval expires, a system reset is generated. If the watchdog
function is not needed in an application, the module can be configured as an interval timer and can generate
interrupts at selected time intervals.
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