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Merge pull request #2200 from haukepetersen/fix_i2c_doc

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driver/i2c: additional docu for pull resistors
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Ludwig Ortmann 2014-12-16 15:36:34 +01:00
commit 17d2f57473
1 changed files with 10 additions and 4 deletions
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14
drivers/include/periph/i2c.h
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@ -15,9 +15,15 @@
* @file
* @brief Low-level I2C peripheral driver interface definition
*
* The I2C signal lines SDA/SCL need external pull-up resistors which connect
* the lines to the positive voltage supply Vcc. The minimum and maximum
* resistances are computed by:
* The I2C signal lines SDA/SCL need external pull-up resistors which connect
* the lines to the positive voltage supply Vcc. The I2C driver implementation
* should enable the pin's internal pull-up resistors. There are however some
* use cases for which the internal pull resistors are not strong enough and the
* I2C bus will show faulty behavior. This can for example happen when connecting
* a logic analyzer which will raise the capacitance of the bus. In this case you
* should make sure you connect external pull-up resistors to both I2C bus lines.
*
* The minimum and maximum resistances are computed by:
* \f{eqnarray*}{
* R_{min} &=& \frac{V_{DD} - V_{OL(max)}} {I_{OL}}\\
* R_{max} &=& \frac{t_r} {(0.8473 \cdot C_b)}
@ -36,7 +42,7 @@
* For more details refer to section 7.1 in:<br>
* http://www.nxp.com/documents/user_manual/UM10204.pdf
*
* @note The current version of this interface only supports the
* @note The current version of this interface only supports the
7-bit addressing mode.
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>