Shifts out a byte of data one bit at a time. Starts from either the most (i.e. the leftmost) or least (rightmost) significant bit. Each bit is written in turn to a data pin, after which a clock pin is pulsed (taken high, then low) to indicate that the bit is available.
Note- if you're interfacing with a device that's clocked by rising edges, you'll need to make sure that the clock pin is low before the call to shiftOut(), e.g. with a call to digitalWrite(clockPin, LOW).
This is a software implementation; see also the SPI library, which provides a hardware implementation that is faster but works only on specific pins.
shiftOut(dataPin, clockPin, bitOrder, value)
- dataPin: the pin on which to output each bit. Allowed data types: int.
- clockPin: the pin to toggle once the dataPin has been set to the correct value. Allowed data types: int.
- bitOrder: which order to shift out the bits; either MSBFIRST or LSBFIRST. (Most Significant Bit First, or, Least Significant Bit First).
- value: the data to shift out. Allowed data types: byte.
For accompanying circuit, see the tutorial on controlling a 74HC595 shift register.
※ NOTES AND WARNINGS:
The dataPin and clockPin must already be configured as outputs by a call to pinMode().
shiftOut is currently written to output 1 byte (8 bits) so it requires a two step operation to output values larger than 255.