JeeLabs: Analog on the cheap

Digital chips can’t do analog directly– you need an A/D converter for that, right?

Not so fast. Just as pulse-width modulation (PWM) can be used to turn a purely digital signal into a varying analog voltage, there are tricks to measure analog values as well.

All you need is the proper software, a simple analog comparator, and these components:

This week’s episode examines delta-sigma modulation and shows you how it’s done:

• Measuring voltage without ADC– Wed
• 10-bit ADC on LPC810 and 812– Thu

There’s in fact a little gem hidden inside those LPC8xx chips which allows implementing this without bogging down the µC. Just one interrupt whenever a measurement is ready. But the basic idea is applicable to any microcontroller with a built-in analog comparator.

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