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How does the mcp23017 connect to the Arduino?
We connect pin 12 of the MCP23017, which is SCL (serial clock line) to analog pin 5 of the arduino. This allows the clock synchrony from the arduino to the I/O port expander chip.
How is data sent in a UART Protocol?
First, and it seems to be obvious, the UART is a serial protocol, which means that the data is sent bit by bit via the single line (unlike parallel protocols where the data is sent via several lines simultaneously). Second, the data is normally sent with the least significant bit first.
Can a mcp23017 be used as a port expander?
It’s actually possible to drive multiple port expanders giving you a huge boost in the number of inputs or outputs available. Adding another MCP23017 would increase the GPIO count from 31 to 47 (15 + 16 + 16). All for a few £/$. The great thing with these devices is that they are cheap (a couple of £/$) and require very few external components.
How many wires do you need for UART?
UART communication. As you can see, only three wires are required – two for the signals, and one for connecting the devices’ ground. Please note that the signal lines are crossed, so the Tx of one device is connected with the Rx of another one and vice versa.
What is the unique address for mcp23017 pins?
Being that we are grounding all 3 pins, the address will for the address pins will be 000. But if you are connecting up to 8 MCP23017s, you will need to configure these pins so that each has a unique address: 000, 001, 010, 011, 100, 101, 110, 111. This way, you will be able to uniquely address each of them.
What can the mcp23017 be used for?
Instead an interrupt service routine can be used to react quickly to an input change on any pin e.g. a key press etc. The MCP23017 has internal pullups for each input pin (configurable) so there is no need to add external pull up resistors for inputs such as push buttons etc.
What is the I2C address of the mcp23017?
Finally we have the three hardware address pins 15~17. These are used to determine the I2C bus address for the chip. If you connect them all to GND, the address is 0x20. If you have other devices with that address or need to use multiple MCP23017s, see figure 1-2 in the datasheet.