Applied Embedded Electronics

Chapter 8. Driving Peripheral Devices

Drive and sense circuits connect the analog world of nondigital devices to digital control signals. Driver circuit is the generic name for circuits that provide suitable voltage and current to peripheral devices. Depending on the device, the needed currents and voltages are often beyond the capability of any digital control unit (DCU) output. As well, driving many devices requires signals that are of an analog nature, necessitating some form of digital-to-analog conversion (DAC) strategy. A sense circuit monitors real-world analog information and converts that information to digital data suitable for DCU processing. Chapter 9 is dedicated to exploring sensors and the circuit methods used to support them.

Figure 8-1 illustrates sense/drive concepts. A driver circuit provides high power to a motor and a sensor circuit determines the rotational speed of the motor. Devices can be operated without feedback sensing (aka open loop), or in conjunction with feedback within a closed-loop control system (FDI: Control).

Figure 8-1. Drive and sense systems

This chapter focuses on driver circuitry. Other chapters focus on sense circuitry and closed-loop control methods.

Warning

WARNING: Safety First! As designers start controlling motors and other servomechanisms, safety must be a priority. Always consider what could possibly happen with an active system ...