# ConnectCore 9C and I2C BUS

**URL:** <https://forums.digi.com/t/connectcore-9c-and-i2c-bus/6294>\
**Category:** Windows CE\
**Created:** [April 21, 2010, 1:06am UTC](https://forums.digi.com/t/connectcore-9c-and-i2c-bus/6294 "2010-04-21T01:06:47Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mfogaca](https://avatars.discourse-cdn.com/v4/letter/m/ba9def/32.png) [@mfogaca](https://forums.digi.com/u/mfogaca)\
**Post date:** [April 21, 2010, 1:06am UTC](https://forums.digi.com/t/connectcore-9c-and-i2c-bus/6294/1 "2010-04-21T01:06:47Z")

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We are trying to use the I2C BUS of the ConnectCore 9C dev board to connect a I2C multiplex chip (PCF8575 - 16 I/O expander). But we are only able to address the higher I/o ports (P8 to P15). We used the sample (I2C GPIO) provided by the dev kit as a reference and the necessary changes have been made according to the chip datasheet and specifications.  
By the way, the on-board (dev kit) chip (PCA9554), a 8 ports I/O expander, works ok.

Someone managed to run the I2C BUS with a I2C device (chip) other than PCA9554 ?

We are using C# and the Digi BSP.

Regards,

Marcos Fogaca

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**Author:** ![jsanz](https://avatars.discourse-cdn.com/v4/letter/j/dec6dc/32.png) [@jsanz](https://forums.digi.com/u/jsanz)\
**Post date:** [October 20, 2010, 12:20pm UTC](https://forums.digi.com/t/connectcore-9c-and-i2c-bus/6294/2 "2010-10-20T12:20:51Z")

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mfogaca,

Have you found any solution?? Nearly, I have had to work with I2C bus and a DS1338 RTC chip and finally I found the solution.