Much more expensive mcp3008 or cd4051 to read a potentiometer ?


I tested the access to time of CD4051 and MCP3008 to read a potentiometer.
The two time measures appear identical.

What is the advantage of using a much more expensive MPC3008 than the CD4051 (cascaded ?) in the case of analog sensors?

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The MCP3008 is an ADC, the 4051 is an analog switch.

The MCP3008 includes an internal analog switch and sample/hold circuitry.

Since pcb area / enclosure is usually more expensive than the components on/in it, any chip
that reduces the parts count is usually cheaper overall. If you have already got an ADC
built into your microcontroller only an external multiplexer might be needed, although
most Arduino already have at least 6-way analog multiplexer and ADC built in.

Say you wanted 18 bit ADC, such as an ADS8885, which only has 2 inputs, then an
external multiplexer would be needed for more inputs, as you won't find many options
for true 18 bit precision DC ADCs out there.

If you only need 10bit precision the MCP3008 makes sense for multiple inputs, assuming
you don't already have an ADC built in to the microcontroller. Note that the MCP3008 is
a lot faster than the Uno's ADC, which might affect the choice.

Basically select the right bits from the kit of parts available to match your requirements.

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Thanks :slight_smile:

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