Hardware Flashcards
A real-time control task requires a serial bus interface, the processing of analogue values and a pulse-width modulation system to drive a DC motor. Briefly describe if a microprocessor or microcontroller is the more
appropriate computational platform for such a task. Please explain why this the case. You can assume that medium computational performance is sufficient and that the sample frequencies do not exceed 1kHz.
A microprocessor typically consist of the ALU and the control unit, it connects via various bus systems to external hardware components like RAM, ROM, System Clock, Ethernet adapters as well as SPI, USB or DAC and ADC units (to name a few examples). A microcontroller contains a microprocessor but also includes so called hardware peripherals (the above mentioned components like RAM,ROM, SPI etc) on chip. Hence a microcontroller is the more appropriate choice since less external components are required and a PCB board design would be greatly reduced in complexity compare to a microprocessor system.
Name two criteria for considering the computation result in a real time system as correct
logical and temporal correctness
To measure positions of motors, incremental encoders are typically deployd. Briefly explain how the turning direction (left or right) of a motor can be sensed with an incremental encoder. How many signals are necessary for this? If it helps you, please sketch the signal(s).
With a single rectangular signal from an encoder the direction sensing is impossible since one can not distinguish if a motor turns left or right. Two 90 degree phased shifted signal are required to sense the direction. The signal pattern for forward and backward motion is different and the encoder interface
electronics can distinguish this
