Overview

Most modern microcontrollers provide a range of timers and the MSP430 is no exception. All devices contain two types of timer and some have five. Each type of timer module works in essentially the same way in all devices. Timer_A is identical in almost all MSP430s, for instance, except that a few have a different number of capture/compare channels.

• Watchdog timer: Included in all devices (newer ones have the enhanced watchdog timer+). Its main function is to protect the system against malfunctions but it can instead be used as an interval timer if this protection is not needed.

• Basic timer1: Present in the MSP430x4xx family only. It provides the clock for the LCD and acts as an interval timer. Newer devices have the LCD_A controller, which contains its own clock generator and frees the basic timer from this task.

• Real-time clock: In which the basic timer has been extended to provide a real-time clock in the most recent MSP430x4xx devices.

• Timer_A: Provided in all devices. It typically has three channels and is much more versatile than the simpler timers just listed. Timer_A can handle external inputs and outputs directly to measure frequency, time-stamp inputs, and drive outputs at precisely specified times, either once or periodically. There are internal connections to other modules so that it can measure the duration of a signal from the comparator, for instance. It can also generate interrupts. We used a few of its capabilities in earlier chapters and most of...