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→MCP23017 I2C Address
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====MCP23017 I2C Address ====
−This is where the I2C Address in defined. That is the specific I2C bus address that the MCP23017 will pay attention to, and until it is established that you are communicating with this, there is little point in attempting anything else. It proves that the MCP23017 and the Raspberry Pi are communicating correctly over the I2C bus.
−This can be checked by using a command line tool on the raspberry Pi which communicates with the I2C bus.
− i2cdetect -y 1
−[[File:I2cdetect -y 1 running in the zynthian terminal.png|800px|center|I2cdetect -y 1 running in the zynthian terminal]]
−ONce you have this then you can see that your MCP23017 is connected to Address A 0 . The default onfig. But you can change this if there is a conflict or your MCP23017 board has a different address set up.
−That's what the A0, A1 & A2 pins are for.
−Conversely, if you don't see this, then you aren't ommunicating so you will need to investigate if there is something that is preventing the 12C bus working. It could be a short circuit or a broken wire or perhaps you have got the wires in the wrong order. By enlarge it's fairly forgiving and you probably haven't damaged anything, just . . .
− Make Notes!!
−
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−===How do I connect things at the Raspberry Pi End for an MCP23017?===
===How do I connect things at the Raspberry Pi End for an MCP23017?===