IntermediateTopic 69 of 104Electronics & Embedded
ADC peripherals and sampling
Configure sampling time, reference voltage and resolution.
In depth
Select reference, resolution, sampling time (source impedance must allow capacitor to charge), and trigger. Use oversampling and averaging for noise reduction, DMA for continuous capture, and calibrate offset and gain. Input protection and anti-alias filter come first.
Key points
- Sample-and-hold
- Differential vs single-ended
- Ratiometric measurement
ExampleReading a thermistor divider with a 12-bit ADC and averaging 16 samples.
ADC peripherals only give good results when sampling time, reference and resolution are set correctly, so configuration is a common source of errors.
What is ADC peripherals and sampling?
Configure sampling time, reference voltage and resolution.
Why is it important to understand ADC peripherals and sampling?
ADC peripherals only give good results when sampling time, reference and resolution are set correctly, so configuration is a common source of errors.
Why does a high-impedance source need a longer sampling time?
The sampling capacitor must charge through the source impedance, so a high impedance needs more time for the voltage to settle.
What does the reference voltage do?
It sets the full-scale input range, so an error in the reference causes a proportional error in every reading.
How is ADC peripherals and sampling used in practice?
Typical applications include setting a longer sampling time for a high-impedance sensor, using an external reference for more accurate readings and averaging several conversions to reduce noise in a battery monitor.
What should I learn before ADC peripherals and sampling?
Study "USB basics" first (topic 68 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
What are the key points of ADC peripherals and sampling?
Sample-and-hold. Differential vs single-ended. Ratiometric measurement.
Can you give an example of ADC peripherals and sampling?
Reading a thermistor divider with a 12-bit ADC and averaging 16 samples.
What comes after ADC peripherals and sampling?
The next topic is "DMA", which builds directly on this one.
How difficult is ADC peripherals and sampling?
It is classed as Intermediate in Electronics & Embedded (topic 69 of 104). It is an intermediate topic. Work through the beginner topics in Electronics & Embedded first.