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I have i2c ADC MAX11646(to detect the temperature using LM35), trying to interface with Raspberry Pi through I2C. i2cdetect -y 1 shows the connected i2c devices.

Now I cannot read the ADC values. I've use i2cset -y 1 0x36 0x21 to set the channel 1 and tried i2cget -y 1 0x36 to read the data.

its always returns oxfc . The channel 2 output is always oxff

How can I get the proper result. Any help is appreciated .

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    The datasheet for the device will specify the commands you send, the data returned, and how to interpret the data.
    – joan
    Dec 9, 2016 at 9:15
  • The datasheet doesn't provide any register address to access the ADC output. So I think we just need to access it using the device i2c address. But that's not working in my case
    – Sam
    Dec 9, 2016 at 10:58

1 Answer 1

Reset to default
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As @joan says, the datasheet will help you ...

...The result is transmitted in 2 bytes; first 6 bits of the first byte are high, then MSB through LSB are consecutively clocked out.

So, the first 6 bits are high, hence the values you'll see in the first byte can only be 0xFC to 0xFF.

You need to read 2 bytes instead of 1. I don't think i2cget can do that (without specifying the register address). You might have some luck with i2cdump.

Maybe: i2cdump -y 1 0x36 w

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  • i2cdump showed me a lot of data on the screen. What is it actually? Is it the register output? How really can I get the 10 bit output ?
    – Sam
    Dec 9, 2016 at 11:04
  • really sorry to ask u a lot, I'm a newbie and dont have much knowledge in this.
    – Sam
    Dec 9, 2016 at 11:09
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    It is just a dump of values requested from the device (some may be invalid / non existant). I'd be interested in the first value - that might contain your reading. However, to get the actual 10bit output you really need to do some coding - python, c, whatever, as long as it provides access to i2c
    – KennetRunner
    Dec 9, 2016 at 11:10
  • Oh thankyou for the prompt reply. What does the top row actually mean at the output of i2cdump
    – Sam
    Dec 9, 2016 at 11:16
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    @Sam man i2cdump
    – joan
    Dec 9, 2016 at 11:51

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