The Shift-Register x 4 devices (up to 32 output PINs) Kit for Arduino is described in the article published by Electroschematics.com
One of the goals of this project is providing the users with the option to see how electronic circuits can be done in a simple, even though efficient way. The same applies to the Arduino sketches related to the circuit. Last but not least, these project can be used with other microcontroller boards with the same behavior described in the Arduino sketches.
A daisy chain is an interconnection of computer devices, peripherals, or network nodes in series, one after another. It is the computer equivalent of a series electrical circuit. In personal computing, examples of “daisy-chainable” interfaces include Small Computer System Interface (SCSI) and FireWire, which allow computers to communicate with peripheral hardware such as disk drives, tape drives, CD-ROM drives, printers, and scanners faster and more flexibly than previous interfaces.
This means that there is not only one serial input in the register but also… an exit! This is the pin we will use to daisy chain many 74HC595 together. The mechanism is simple: the clock and latch pins are shared between all the daisy-chained devices while every Q7 PIN of the previous chip in the chain is used as serial input for the following chip. This up to the last device.
This circuit can be considered as a general purpose daisy-chained parallel shift-out register group for a total of 32 output ports that we can easily manage with our Arduino board (or similar microcontroller boards), using only three I/O pin. The four capacitors between the GND pin of every device and the GND signal are designed to give more stability to the system, as suggested in the device data sheet.
Then you will find a some how strange detail: a variable capacitor that can be optionally connected to an analog input of the Arduino. This part of the circuit is not directly involved with the logic of the shift registers, but as we consider to use this board as general purpose, it will be frequent for an analog value to be sent to the microcontroller at least for testing purposes.
The kit includes:
- 35mm X 135mm dual-sided PCB with DIL Socket for the shift-register devices (green coated + silkscreen)
- N.4 74HC595 shift-out register
- N.1 High precision 47K variable potentiometer
- N.4 8 female connectors breadboard-compatible
- N.3 20 cm cables with breadboard-compatible pins
- N.1 20 cm analog input cable with breadboard-compabile pin
- N.1 20 cm power cables with breadboard-compabile pins
- The kit includes 32 LEDs and 32 resistors to start using it and testing your sketches.
The kit has been tested on many different Arduino boards, from duemilanove up to uno, mini, nano and Arduino-compatible boards.
Software and documentation download
- 74HC595 Data Sheet (download 74HC_HCT595)
- ShiftOutX V. 1.0 Arduino library (download ShiftOutX_10)
- ShiftOutX V 1.1 Arduino library, alternative to the version 1.0 supporting also PWM and SPI pins (download ShiftOutX-11)
- In addition you can also download the PDF article published by electroschematics.com (download Arduino Daisy Chain Shift Register with 74HC595 – Part 1)
Optional parts, useful for your knowledge and mentioned in the electroschematics.com article
- ShiftRegister595 Arduino library, managing a single shift register (download ShiftRegister595)
Kit pricing options:
- Full pre-assembled Kit: 20,00 $
- Kit without Test LEDs: 15,00 $
- PCB Only: 11,00 $