An intro to the 74HC595... - Electronic Components & Theory https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/ Discussion board for Robotics, Arduino, Raspberry Pi and other DIY electronics and modules. Join us today! en-US Fri, 04 Sep 2026 20:40:21 +0000 wpForo 60 RE: An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-11187 Fri, 15 May 2020 07:24:33 +0000 @frogandtoad

we bought a new house and have been moving the last week or so. Furniture goes on Monday, so, haven't had much time to play.

time to set up a new shop.

]]> Electronic Components & Theory itsCaseyDambit https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-11187 RE: An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-11167 Thu, 14 May 2020 09:57:20 +0000 @itscaseydambit

Posted by: @itscaseydambit

I'm going to setup the sketch for troubleshooting so I can better show the situation, and return with my problem.

Meanwhile...

Posted by: @frogandtoad

@itscaseydambit

What about: "pgm_read_ptr_near" ?

Posted by: @itscaseydambit

@frogandtoad

pgm_read_byte_near is all it needs. 

No problem... you never actually provided us with a solution to your problem, so I thought I would post an alternative suggestion.  So what exactly was the problem in the end?

 

]]> Electronic Components & Theory frogandtoad https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-11167 RE: An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-11163 Thu, 14 May 2020 05:22:29 +0000 @frogandtoad

pgm_read_byte_near is all it needs. 

]]> Electronic Components & Theory itsCaseyDambit https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-11163 RE: An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10898 Fri, 08 May 2020 12:31:37 +0000 @itscaseydambit

What about: "pgm_read_ptr_near" ?

 

]]> Electronic Components & Theory frogandtoad https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10898 RE: An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10897 Fri, 08 May 2020 12:30:08 +0000 @robo-pi

Posted by: @robo-pi

Hi Casey.

LOL... No, it's Don Knotts :-)

 

]]> Electronic Components & Theory frogandtoad https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10897 RE: An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10889 Fri, 08 May 2020 02:29:06 +0000 @itscaseydambit

Hi Casey.  I thought I should chime in just to let you know that someone read your post.  I downloaded your sketch, and I even opened it in the Arduino IDE briefly just to take a quick peak at it.  Unfortunately I'm quite busy lately and I'm not currently working with 74HC595.   I have used them before on several projects so I'm already familiar with how they work.   In any case, I didn't check out your code yet at all.   But I saved it to my digital chips folder and the next time I'm working with the 74HC595 I'll give it another peek then.

In the meantime, I thought I'd just post a quick reply here so you don't think you're being ignored. 😊 

Just busy with other things right now is all. 😎 

With the nice spring weather I've been playing myself out doing gardening work.

]]> Electronic Components & Theory Robo Pi https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10889 RE: An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10816 Mon, 04 May 2020 11:52:20 +0000 EGADS! Yes, the *buf_p = pgm_read_byte_near() was the correct function call to use, and I'm trying to remember when that got changed (and not returned back to its original state) because the project was always intended to have a  data definition of one byte and not a word (two bytes).

But, the LEDs are not sequencing the way I had planned and something is foul, afoot. And this is where one may find just how valuable the DroneBot Workshop community may indeed be.

I'm going to setup the sketch for troubleshooting so I can better show the situation, and return with my problem.

Meanwhile...

]]> Electronic Components & Theory itsCaseyDambit https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10816 RE: An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10815 Mon, 04 May 2020 05:20:09 +0000 Just when you think you've got it right...

Me thinks on line 216 of the code, it should be:

    *buf_p = pgm_read_byte_near(

not 

    *buf_p = pgm_read_word_near(

Monumental OOOPS!

But, the code still works (I think), it's just reading more than it should from that address. I guess I'll throw the prototype back together again and test some more to make sure. 

]]> Electronic Components & Theory itsCaseyDambit https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10815 An intro to the 74HC595... https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10811 Mon, 04 May 2020 04:51:23 +0000 Ok, my fellow Arduinovians, here's the story. I only became aware of Arduino in early January of 2020 (please don't walk away), and after my introduction to the 74HC595 bit shifter, I had to know what made that little devil tick inside.

Attached is the code I wrote, which is no big thing, BUT, what I'd appreciate is, if there is anyone out there who well knows the 74HC595, please look over the preamble to the code and let me know if I got anything wrong or how I might better express my point.

It's a bit lengthy, granted. My intent was to help those new to bit shifting, and to show that what's ticking inside the 74HC isn't all that difficult to understand, once you put your mind into 0s and 1s.

Muchos thanks!

1665

 

]]> Electronic Components & Theory itsCaseyDambit https://forum.dronebotworkshop.com/electronic-components/an-intro-to-the-74hc595/#post-10811