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Diffstat (limited to 'source/i2c.rst')
| -rw-r--r-- | source/i2c.rst | 27 |
1 files changed, 8 insertions, 19 deletions
diff --git a/source/i2c.rst b/source/i2c.rst index e2a7a04..15190a8 100644 --- a/source/i2c.rst +++ b/source/i2c.rst @@ -1,20 +1,8 @@ .. _i2c: -===== |i2c| ===== -.. FIXME update this documentation once you write the Wire library on -.. top of libmaple i2c. - -.. FIXME generalize Maple-specific documentation - -.. note:: - - The |i2c| interface is currently only available from the 'refactor' - branch of the github `libmaple - <http://github.com/leaflabs/libmaple>`_ repository. - |i2c| is a crude and easy-to-hack serial protocol that requires only two wires/channels for communication between many devices. Every message passed on the bus is between a *master* (who initiates the @@ -26,6 +14,8 @@ Higher level functionality, such as reading a particular register value, is achieved by writing to set the memory location then reading to pull out the data. +.. FIXME [Maple-specific values] + Note that the master/slave designation is on a message-by-message basis. The Maple can act as both a master (messages initiated by user code) and slave device (responding to requests via configurable @@ -37,8 +27,8 @@ interrupt handlers) at the same time. Hardware/Circuit Design ----------------------- -The Maple has two |i2c| ports. Port 1 (i2c1) has SDA on header D9 and -SCL on D5; Port 2 (i2c2) has SDA on D30 and SCL on D29. +The Maple has two |i2c| ports. Port 1 (I2C1) has SDA on header D9 and +SCL on D5; Port 2 (I2C2) has SDA on D30 and SCL on D29. The Maple reliably communicates with up to a 400kHz clock speed; this doesn't translate into a 400kbps data rate except in extreme cases @@ -60,16 +50,15 @@ oscilloscope to debug any issues. Function Reference ------------------ -The function API for |i2c| is not finished! See the `source code -<https://github.com/leaflabs/libmaple/blob/refactor/libmaple/i2c.h>`_ -for now. +Currently, only low-level support in :ref:`libmaple-i2c` exists. A +Wiring-style library is planned for a future release. SMBus ----- The STM32 microcontroller has hardware support for SMBus; we simply -have not written software for it. The SMBAL line for i2c1 is on header -D4 and for i2c2 is on D31. +have not written software for it. The SMBAL line for I2C1 is on header +D4 and for I2C2 is on D31. .. _i2c-recommended-reading: |