Why only 10 bits?
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| Author | Content |
|---|---|
| penguinist May 25, 2016 10:39 PM EDT |
This is something that is totally amazing to me. The RPi hobby people are fixated on the MCP3008 analog to digital converter. This chip is very easy to interface to the RPi's spi bus (only four wires to connect) and offers eight analog inputs at 10 bits resolution at a chip price of $3.50. That all sounds pretty good doesn't it. Well what everyone seems to be ignoring is that there is another chip in that same family (pin compatible) and selling at the same price that offers 8 channels of analog inputs at 12 bits resolution. That part is the MCP3208. That is my go-to solution whenever I need analog on an RPi. Why would you divide your analog measurements into 1024 increments when you could get 4096 increments at the same price? What I totally fail to understand is why RPi vendors like Adafruit continue to promote the 10-bit part when the 12-bit part is so superior and equally easy to interface. Now here we have a new Kickstarter project and look at what they are doing for ADC. 10-bits! go-figure... The blind appear to be leading the blind. |
| dotmatrix May 26, 2016 10:19 AM EDT |
Digikey prices. MCP3008 ==> $166.00 / 100C MCP3208 ==> $264.00 / 100C This is the problem buying a pre-built 'something' ... you typically get less for more. However, since you don't need to assemble everything yourself by hand, maybe it almost all comes out in the wash. There are sometimes advantages to using a lower resolution ADC, especially in memory limited or processor limited devices. |
| penguinist May 26, 2016 3:59 PM EDT |
The price I pay for the 12-bit MCP3208 from Element14 is actually less than people are paying for the 10-bit part from Adafruit. I'm just saying... > There are sometimes advantages to using a lower resolution ADC, especially in memory limited or processor limited devices. That statement I will probably take issue with. Both a 10 bit value and a 12 bit value will fit equally well in the same two byte space, so even on low end devices (and the RPi really no longer deserves that label by the way) memory becomes a non-factor. My purpose here is simply to alert my LXer friends that there is a low cost 12 bit option available. Next project consider using this higher resolution alternative. |
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