Adc interfacing
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The document discusses analog to digital conversion. It explains that sensors output analog signals that are converted to digital signals by an analog to digital converter (ADC) for processing by a microcontroller. The ADC in the Atmega8 microcontroller provides 10-bit resolution and converts signals at a frequency between 50-200kHz, determined by the clock frequency and a prescaler. There is a tradeoff between conversion frequency and accuracy, with higher frequencies providing less accuracy. The document also describes the ADMUX register that controls the ADC.
Adc interfacing
- 2. In the Real World, a sensor senses any physical parameter and converts into an equivalent analog electrical signal. For efficient and ease of signal processing, this analog signal is converted into a digital signal using an Analog to Digital Converter (ADC). This digital signal is then fed to the Microcontroller (MCU) and is processed accordingly.
- 6. The ADC of the AVR converts analog signal into digital signal at some regular interval Determined by the clock frequency ADC operates within a frequency range of 50kHz to 200kHz But CPU clock frequency is much higher (in the order of MHz) Frequency division must take place The prescaler acts as this division factor
- 7. Out of the 50kHz-200kHz range of frequencies, which one do we need? There is a trade-off between frequency and accuracy Greater the frequency, lesser the accuracy and vice-versa So, if your application is not sophisticated and doesn’t require much accuracy, you could go for higher frequencies
- 8. 1. ADMUX – ADC Multiplexer Selection Register
- 13. Bit 7 – ADEN – ADC Enable Bit 6 – ADSC – ADC Start Conversion Bit 5 – ADFR – ADC Free Running Select Bit 4 – ADIF – ADC Interrupt Flag Bit 3 – ADIE – ADC Interrupt Enable Bits 2:0 – ADPS2:0 – ADC Prescaler Select Bits