I recently ordered and CJMCU-200 FT200XD a USB to I2C and I am trying to read information from a BME280 using it's I2C output. I am new to FTDI and am having some trouble finding information on how to setup such a device. I plan to write a program the would read in the serial data. My question is did I get the right kind of USB to I2C chip? I have been reading other questions and the problem half the time is the wrong chip.


closed as too broad by Chris Stratton, Elliot Alderson, Finbarr, Lior Bilia, Voltage Spike Feb 8 at 17:37

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  • \$\begingroup\$ There are cloned FTDI chips around that don't work properly with official drivers. \$\endgroup\$ – Spehro Pefhany Feb 5 at 15:19
  • \$\begingroup\$ I have installed the drivers and the suggested program to interface but I don't get consistent results. I am guessing that I am missing something. \$\endgroup\$ – Michael H. Feb 5 at 17:42
  • \$\begingroup\$ @MichaelH. You'll need an oscilloscope and look at the lines, you should at least be able to send commands and 'toggle' the lines. Make sure you have pull ups \$\endgroup\$ – Voltage Spike Feb 8 at 17:37

No. What is needed is a USB chip than can act as a I2C master. FT200XD is a I2C slave chip, so it cannot be used as a master to talk to another I2C slave like the BME280 in the question.

  • 3
    \$\begingroup\$ +1 good point, the datasheet says, on p.12, "The FT200XD device only operates as a slave," \$\endgroup\$ – Ale..chenski Feb 5 at 17:54
  • \$\begingroup\$ Yeah I caught the slave thing a bit to late. Thank you for the information. \$\endgroup\$ – Michael H. Feb 5 at 19:52

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