| 摘要 |
A low-power programmable alarm clock system is provided for use with microprocessor-based reflectance photometer systems for generating an alarm control signal at pre-programmed alarm activation times. The system utilizes an alarm clock circuit which includes means for storing a count value corresponding to the number of predefined time periods existing between a given instantaneous time and a pre-programmed alarm activation time, means for generating a signal corresponding to the passage of each of said predefined time periods and using the generator signal to increment the stored count value each time the predefined time period has elapsed, and means for generating an alarm activation signal when the stored count value has been incremented to a predefined activation value. The programmable alarm clock circuit operates in conjunction with a transistor-based switching arrangement and the system microprocessor in such a way that the required count value is calculated and stored into a shift register/counter each time the reflectance photometer system is powered down and an alarm function is found to be activated. The alarm clock circuit then takes over and operates under negligible power consumption conditions and generates an alarm control signal which reactivates the overall system circuitry when the pre-programmed alarm activation time has been reached. <IMAGE> |
