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Data Acquisition and Manipulation

Data Acquisition and Manipulation. Analog Vs. Digital Quantities. Elements of a Data Acquisition System. Signal Digitization. Aliasing Effects. Sample and Hold. Sample and Hold Characteristics. A/D Conversion Basics. A/D Resolution and Quantization Error. Quantization Error.

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Data Acquisition and Manipulation

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  1. Data Acquisition and Manipulation

  2. Analog Vs. Digital Quantities

  3. Elements of a Data Acquisition System

  4. Signal Digitization

  5. Aliasing Effects

  6. Sample and Hold

  7. Sample and Hold Characteristics

  8. A/D Conversion Basics

  9. A/D Resolution and Quantization Error

  10. Quantization Error

  11. 16F877 A/D Converter

  12. Analogue Input Model

  13. Timing Requirements for One A/D Conversion

  14. A/D Conversion Steps 1. Configure the A/D module: Configure analog pins/voltage reference and digital I/O (ADCON1) Select A/D input channel (ADCON0) Select A/D conversion clock (ADCON0) Turn on A/D module (ADCON0) 2. Configure A/D interrupt (if desired): Clear ADIF bit Set ADIE bit Set PEIE bit Set GIE bit 3. Wait the required acquisition time. 4. Start conversion: Set GO/DONE bit (ADCON0) 5. Wait for A/D conversion to complete, by either: Polling for the GO/DONE bit to be cleared (with interrupts enabled); OR Waiting for the A/D interrupt 6. Read A/D result register pair (ADRESH:ADRESL), clear bit ADIF, if required. 7. For the next conversion, go to step 1 or step 2, as required. The A/D conversion time per bit is defined as TAD.

  15. Acquisition Time

  16. A/D Conversion Clock • The A/D conversion time per bit is defined as TAD. • The A/D conversion requires a minimum 12TAD per 10-bit conversion. • The source of the A/D conversion clock is software selected. • TAD must be selected to ensure a minimum TAD time of 1.6 µs.

  17. A/D CONVERSION TAD CYCLES

  18. A/D Result Registers

  19. Registers Associated with A/D

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