Pullup with logger shield

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spiney
 
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Pullup with logger shield

Post by spiney »

The logger shield with RTC uses I2C, I believe. The documentation does not mention pullup resistors, but other I2C sensors need pullups to either 3.3 or 5Volts. So my worry is that there may be internal pullups to 5v to enable the shield to work and that may harm 3.3V sensors.

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adafruit_support_bill
 
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Re: Pullup with logger shield

Post by adafruit_support_bill »

Yes, there are 5v pullups on SDA and SCL. For 3.3v sensors, an i2c-safe level shifter should be used: http://www.adafruit.com/products/757

Another alternative is to remove the pullups (r1 & r2) and install pullups from the SDA & SCL breakout holes to 3.3v.

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spiney
 
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Re: Pullup with logger shield

Post by spiney »

Thank you.

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