| Popis: |
This chapter discusses the practicalities of attaching sensors and actuators to digital controllers. The example of RCM3400 prototyping board is used for all the examples in this chapter, the concepts covered are applicable to most embedded systems. Transistor–transistor logic (TTL)-based digital systems were designed to operate on 5-volt rails. As new complementary metal–oxide semiconductor (CMOS) logic technologies have become mature and robust, there has been a natural migration to lower voltage systems. As digital states change, these parasitic capacitors must be charged and discharged. The resistive paths through which this charge is moved dissipate power. The more capacitive nodes involved in a system level state change mean more energy that must be moved and power dissipated. The faster the state changes occur means more power is dissipated over a given time interval. In this age of laptop computers, personal digital assistant (PDAs) and cell-phones, energy storage directly translates to weight (and volume). Ultimately, the push for smaller, lighter, portable, energy efficient devices has pushed the digital world to lower supply rails. Some core modules from Rabbit Semiconductor have provided low noise data acquisition (DAQ) channels. |
