8-bit Parallel to Serial Conversion using Multiplexer and Counter

Data Acquisition System

• The first 8-bit group of parallel data is applied to the inputs of the MUX, and each bit is serially selected and passed through the MUX to the output line.
• After 8-CLK pulses, the data byte has been converted to a serial format and sent out through the transmission line.

Analog to Digital Converter (ADC)

• An ADC is an electronic integrated circuit that converts a signal from analog to digital form.
• ADC provides a link between the analog world of transducers and the digital world of signal processing and data handling.

Process of Analog to Digital Conversion

• The process involves three steps: sampling and holding, quantizing, and encoding.
• Sampling and holding involves sampling the voltage of a continuously varying analog signal and holding its value at a constant level for a specified minimum period of time.
• Quantizing involves breaking down the analog value into a set of finite states.
• Encoding involves assigning a digital word or number to each state and matching it to the input signal.

Sampling and Holding Circuit

• The circuit is an analog device that samples the voltage of a continuously varying analog signal and holds its value at a constant level for a specified minimum period of time.
• The processed analog signal is given to an analog multiplexer, which switches sequentially between a number of different analog input channels.
• Each input is connected to the output of the multiplexer for a specified period of time, and a sample-hold circuit acquires the signal voltage and holds its value while an A/D converter converts the value into digital form.

Objectives of Data Acquisition System

• The system must acquire the necessary data at the correct speed.
• The system must use all data efficiently to inform the operator about the state of the input.
• The system must monitor the complete plant operation to maintain online optimum and safe operation.
• The system must be able to summarize and store data for diagnosis and record purposes.
• The system must be flexible and capable of being expanded for future requirements.
• The system must provide an effective human communication.

Application of Data Acquisition System

• Analog DAS is used when wide frequency width is required or when lower accuracy can be tolerated.

Elements of Data Acquisition System

• DAC = Digital to Analog Converter
• EOC = End of Conversion
• SAR = Successive Approximation Register
• S/H = Sample and Hold Circuit
• Vin = Input Voltage
• Comparator Vref = Reference Voltage

Successive Approximation Register (SAR) Algorithm

• The algorithm uses an n-bit DAC and original analog results.
• It performs a binary comparison of VDAC and Vin.
• MSB is initialized at 1 for DAC.
• If Vin < VDAC (VREF / 2^n), then MSB is reset to 0.
• If Vin > VDAC (VREF / 2^n), then the successive bits are set to 1; otherwise, 0.
• The algorithm is repeated up to LSB.
• At the end, DAC in = ADC out.
• N-bit conversion requires N comparison cycles.

Advantages of SAR ADC

• Capable of high speed and reliable operation.
• Medium accuracy compared to other ADC types.
• Good trade-off between speed and cost.
• Capable of outputting the binary number in serial (one bit at a time) format.

This quiz covers the process of converting an 8-bit parallel data into a serial format utilizing a Multiplexer (MUX) and counter. The data is serialized by selecting each bit sequentially through the MUX and sent out through a transmission line after 8 clock pulses. The process repeats for each byte of data.