Chapter 17 74HC595 & LEDBar Graph
Component knowledge
74HC595
74HC595 chip is used to convert serial data into parallel data. 74HC595 can convert the serial data of one
byte to 8 bits, and send its corresponding level to the corresponding 8 ports. With this feature, 74HC595 can
be used to expand the IO port of Arduino board. At least 3 ports on the RPI board are need to control 8 ports
of 74HC595.
The ports of 74HC595 are described as follows:
The positive electrode of power supply, the voltage is 2~6V
The negative electrode of power supply
Enable output,
When this pin is in high level, Q0-Q7 is in high resistance state
When this pin is in low level, Q0-Q7 is in output mode
Parallel update output: when its electrical level is rising, it will update the
parallel data output.
Serial shift clock: when its electrical level is rising, serial data input register will
do a shift.
Remove shift register: When this pin is in low level, the content in shift register
will be cleared .
Serial data output: it can be connected to more 74HC595 in series.
For more detail, please refer to the datasheet.
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