What is Admux in AVR?
The ADMUX register is as follows. ADMUX Register. The bits that are highlighted are of interest to us. In any case, we will discuss all the bits one by one. Bits 7:6 – REFS1:0 – Reference Selection Bits – These bits are used to choose the reference voltage.
What is Admux register?
ADMUX – ADC Multiplexer Selection Register. This register is used to select reference voltage source, how the result should be stored (either left adjusted or right adjusted), analog port channel to be used for conversion.
What are the modes in ADC?
The ADC has two fundamental operation modes: Single Conversion and Free Running. In Single Conversion mode, you have to initiate each conversion. When it is done, the result is placed in the ADC Data register pair and no new conversion is started.
What is ADC register?
The ADC uses registers ADMUX, ADCSRA, ADCL, ADCH, ADCSRB, and DIDR0 to configure the hardware and to do analog to digital conversion. Along with register configuration, ADC hardware also needs a separate analog supply voltage pin, AVCC. AVCC must not differ more than ±0.3V from VCC.
What is ADC in AVR?
Introduction. ADC (Analog to Digital converter) is the most widely used device in embedded systems which is designed especially for data acquisition. In the AVR ATmega series normally 10-bit ADC is inbuilt in the controller.
How do ADC channels work?
The ADC converts an analog input voltage to a 10-bit digital value. The ADC is connected to an 8-channel Analog Multiplexer which allows each pin of PortA to be used as input for the ADC. The analog input channel is selected by writing to the MUX bits in ADMUX.
What is free running mode?
Free running mode means, the ADC is automatically starting a new conversion each time the last one finished. You don’t have to retrigger the ADC in this mode.
What is Burst mode in ADC?
In Burst mode, the ADC samples a configurable number of samples as fast as possible after a single trigger. The conversion results are accumulated into a single ADC result. A maximum of 1024 samples can be accumulated on a single ADC conversion trigger.
What is ADC clock cycle?
The ADC needs a minimum of 2.5 clock cycles for the sampling and 12.5 clock cycles for conversion for 12-bit mode. With a 60 MHz ADC clock, it can achieve 4 mega sample per second. For a higher sampling speed, it is possible to reduce the resolution down to 10, 8 or 6 bits.
What is ADC system?
In electronics, an analog-to-digital converter (ADC, A/D, or A-to-D) is a system that converts an analog signal, such as a sound picked up by a microphone or light entering a digital camera, into a digital signal.
What is ADC Auto Trigger?
The auto triggering mode provides a method of starting conversions at fixed intervals, which are configurable, based on the trigger source. The ADC Interrupt Flag bit in ADCSRA (ADCSRA. ADIF) will be set even if the specific interrupt or global interrupts are disabled. Thus a conversion can be triggered using ADCSRA.
What is polling in ADC?
Polling would mean you spinning in a loop wait for the conversion to complete, performing no other useful work. With multiple channels, and interleaving, the model is to use DMA to capture the data into an array, ideally one containing 100’s of samples, and calling an interrupt to process once complete.
What is sampling time for ADC?
The sampling time is the ADC clock cycles for which the sample and hold capacitor is charged up to the channel input voltage. The ADC then requires another 12 clock cycles to convert to 12 bits accuracy.
How is ADC speed calculated?
For example if the ADC clock is 12MHz and the sampling time is 84 clock cycles then total conversion time will be 84 + 12 ADC cycles = 8us, and max ADC sample speed = 1/8us = 125kSPS.
What is DCA and ADC?
Data converters provide a transition between the analog and digital signal realms. The two basic converter types, analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), share many common circuit elements and even come in similar multi-pin packages.