Which pins are which on a shift register? What pins on a 74HC595 shift register are the data, clock, and latch pins?
I just bought an arduino and was trying to do this tutorial http://www.instructables.com/id/Arduino-Expermentation-Kit-How-to-get-Started-wi/step7/8-More-Leds-74HC595-Shift-Register-CIRC05/ . I have hit some trouble though and I am confused when it comes to the shift registers. When he says to connect to the clock pin, do we connect to the SCK (Shift Register Clock Input) or the RCK (Storage Register Clock Input)? When he says to connect to the data pin, do you connect to the SI (Serial Data Input)? Also what does he mean when you say to connect to the latch pin? The data sheet for the Digikey shift register I am using is in the link below.http://www.fairchildsemi.com/ds/MM/MM74HC595.pdf?
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Best tutorial I know of to use the 595 shift register:
http://www.arduino.cc/en/Tutorial/ShiftOut
Clock moves the data down the register.
Data is the ones and zeros to be shifted in/out (theres a data in and out)
Latch moves the data from the shift register to the output register.
Enable is a gate that turns all the outputs off, regardless of their value.
Data is clocked in, one bit at a time. This has no effect on the outputs -- data just shifts into the shift register. When you bring up the latch, it copies the shift register's values to the output pins. Hope that helps.
http://www.arduino.cc/en/Tutorial/ShiftOut
Clock moves the data down the register.
Data is the ones and zeros to be shifted in/out (theres a data in and out)
Latch moves the data from the shift register to the output register.
Enable is a gate that turns all the outputs off, regardless of their value.
Data is clocked in, one bit at a time. This has no effect on the outputs -- data just shifts into the shift register. When you bring up the latch, it copies the shift register's values to the output pins. Hope that helps.
Feb 3, 2010. 1:44 PMRe-design
says:
Page 3 of this datasheet has a list of the pin functions. Anytime you don't know the pinout or function or use etc. of a chip you can google the "name datasheet" and find these fact sheets that the mfg. have prepared.
When he says to connect to the data pin, do you connect to the SI (Serial Data Input)?
> Yes. Pin 14 on your IC, "SER"
When he says to connect to the clock pin, do we connect to the SCK (Shift Register Clock Input) or the RCK (Storage Register Clock Input)?
> In short.... you need to connect both. The timing diagram of page 9 of the pdf file you linked to explains this quite well, much better than I can with words. The SCK is pulsed every time, when the shift register is full and you want to send it out you make the RCK pin high to make the register store the values that are present at the output (Q) of the shift register. You can now start loading in more values with the SER pin, pulsing SCK.
Feb 3, 2010. 7:44 AMStoned (author)
says:
So if I am understanding you correctly, the clock pin is the SCK pin and the latch pin is the RCK pin?
I've never used this chip before, but with a quick scan of the spec. sheet; yes I think so.
(would be nice if someone could confirm what I've said for Stoned's benefit)
(would be nice if someone could confirm what I've said for Stoned's benefit)
I've built a shift pcb just a few weeks ago - when its done it will cascade hundreds of leds...
You are exactly right on how it works.
You are exactly right on how it works.
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