26 lines
1.1 KiB
Markdown
26 lines
1.1 KiB
Markdown
#SPI - Serial Peripheral Interface
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###Known as the four-wire serial bus, SPI lets you daisy-chain multiple compatible devices off a single set of pins by assigning them different addresses.
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A simple example of an SPI peripheral is the MCP23S17 digital IO expander chip Note the S in place of the 0 found on the I2C version. Using it in WiringPi2 is a doddle:
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```python
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import wiringpi2 as wiringpi
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HIGH = 1
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OUTPUT = 1
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PIN_BASE = 65
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SPI_ADDR = 0x20
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wiringpi.wiringPiSetup()
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wiringpi.mcp23S17Setup(PIN_BASE,SPI_ADDR)
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# 16 pins including the starting pin
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mcp23S17pins = range(PIN_BASE,PIN_BASE+15)
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for pin in mcp23S17pins:
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wiringpi.pinMode(pin,OUTPUT)
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wiringpi.digitalWrite(pin,HIGH)
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```
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You can also use the SPI port to "Bit-Bang" an ATmega 328, loading Arduino sketches onto it with Gordon's modified version of AVRDude.
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Hook up you Pi's SPI port to that of your ATmega, and power the ATmega from the 3.3v pin on the Pi. Make sure you're not running any SPI device drivers, and run "avrdude -p m328p -c gpio" to verify the connection.
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See the individual pins to learn how to connect up your ATmega. |