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| -rw-r--r-- | source/i2c.rst | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/source/i2c.rst b/source/i2c.rst index 31976ac..8f1b26f 100644 --- a/source/i2c.rst +++ b/source/i2c.rst @@ -7,17 +7,18 @@ two wires/channels for communication between many devices. Every message passed on the bus is between a *master* (who initiates the message) and a *slave* device. Slaves are addressed using 7-bit -addresses (up to 127 unique devices); 10-bit addressing is possible, -but currently unimplemented. Every message consists of an arbitrary -combination of 8-bit reads and writes as requested by the master. -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. +addresses (up to 127 unique devices); 10-bit addressing is also +possible. Every message consists of an arbitrary combination of 8-bit +reads and writes as requested by the master. 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. Note that the master/slave designation is on a message-by-message basis. Maple can act as both a master (messages initiated by user code) and slave device (responding to requests via configurable -interrupt handlers) at the same time. +interrupt handlers) at the same time (though slave mode is currently +unimplemented). .. contents:: Contents :local: @@ -28,10 +29,10 @@ Hardware/Circuit Design .. FIXME [0.1.0] Link to board-specific values (BOARD_I2C1_SDA_PIN, etc.) Maple boards have two |i2c| ports. Maples reliably communicate with -up to a 400kHz clock speed; this doesn't translate into a 400kbps data -rate except in extreme cases because of addressing and protocol +up to a 400kHz clock speed; this doesn't translate into a 400kbps +data rate except in extreme cases because of addressing and protocol overhead. We have tested clock speeds up to a megahertz and have had -mixed results; in theory it could be possible to achieve even higher +mixed results; in theory, it could be possible to achieve even higher rates, but signal quality degrades rapidly, and the bus becomes unreliable. |