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How can I read an analog signal without an ADC?
The resistor and capacitor in series make an RC circuit, which you would connect to a DI pin on your MCU. In a nutshell, you would be able to determine the varying resistance of the thermistor by measuring its RC time constant, and from there calculate the ambient temperature. You would need to know a few things first.
Can a microcontroller do an analog to digital conversion?
Not every pin on a microcontroller has the ability to do analog to digital conversions. On the Arduino board, these pins have an ‘A’ in front of their label (A0 through A5) to indicate these pins can read analog voltages. ADCs can vary greatly between microcontroller.
How does an ADC work in a microcontroller?
This is because microcontrollers can only see “levels” of the voltage, which depends on the resolution of the ADC and the system voltage. ADCs follow a sequence when converting analog signals to digital.
Is it possible to read analog signals on a MCU?
If you are out of Analog Inputs (AIs) on your MCU, or do not have any AIs at all, it’s possible to rig together a way to read analog signals that use varying resistance levels, even if you only have digital inputs (DIs).
How many connections does a microcontroller ADC need?
Microcontroller ADCs are generally happy to use the supply rails as reference. You must make four connections to the device under test. Two of the connections deliver the current, and two of the connections present the voltage across the device under test to the measurement circuit.
How to calculate the resistance of a capacitor?
Once you know the time constant by timing how long it takes for the DI to flip high, since you know the capacitor values, the resistance value is easy to calculate: R=t/C. You will want to set the I/O pin to low to discharge the capacitor first, making sure to keep it low for at least 5RC (five times R times C.)
What is the output resistance of an AVR digital out?
The output resistance of an AVR digital out is about 25 ohms: . The +5V line is used for the reference of both the current source and ADC. Variations in supply voltage will cancel. The alternative would be to have a reference in the current source and a reference in the ADC… not necessary here.