twatts Posted February 11, 2021 Share Posted February 11, 2021 Hello, I am trying to communicate with an MCP4441 chip using the I2C interface and using an Aardvark I2C cable from Total Phase. I am trying to read the registers which have non-zero default values (2,3,8,9), but always get back 0. It appears from the data sheet for the part that the control byte should be 0x59 is A1:A0 = 00 (see attached page from datasheet) I have attached scope captures of SCL and SDA when I tried setting the write and read address to 0x59 and 0x2c. Both of these attempts read back 0. Any ideas on what I am doing wrong? Thanks. Quote Link to comment Share on other sites More sharing options...
0 holdmybeer Posted February 17, 2021 Share Posted February 17, 2021 I've decoded your scope plot. The first one looks right, but note you get a NAK back, which simply means no device feels addressed to respond. The second one is shifted by one with an added 1, this doesn't seem to be right according to the datasheet. What about the A0 and A1 pins? Look here: The A0 and A1 pin will determine the address, the default case seems to be an internal pull up, so A0 and A1 are both 1, not 0. Might this be the problem why the chip doesn't react? Quote Link to comment Share on other sites More sharing options...
0 Member Orunmila Posted February 23, 2021 Member Share Posted February 23, 2021 I have also catalogued a number of typical I2C errors including typical addressing errors in this blog post Quote Link to comment Share on other sites More sharing options...
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twatts
Hello,
I am trying to communicate with an MCP4441 chip using the I2C interface and using an Aardvark I2C cable from Total Phase.
I am trying to read the registers which have non-zero default values (2,3,8,9), but always get back 0.
It appears from the data sheet for the part that the control byte should be 0x59 is A1:A0 = 00 (see attached page from datasheet)
I have attached scope captures of SCL and SDA when I tried setting the write and read address to 0x59 and 0x2c.
Both of these attempts read back 0.
Any ideas on what I am doing wrong?
Thanks.
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