I was playing around with a NodeMCU and a shift register and running LEDs with it worked just fine. But when I hooked up a pin of the shift register to the A0 pin of the NodeMCU I didn't get the value represented by the shift register pin. Why is that and is there a way to read the pins of a shift register?
I think the issue is you are not providing us with enough information to understand your circuit or code. If we were looking over your shoulder and could see your schematic and code, someone might be able to help. However most of us are likely more than 1000 miles away.
Please try to fully explain your circuit, parts and code.
If you post code, please read the "how to use this forum" to learn how to properly post code. It makes it easier on the reader and increases you chances of getting a useful response.
The 74HC595 has a latch which then takes the data to the output pins not to another shift register. To answer your question NO. Typically when this is happening it is typically a hardware problem. Look at your power and be sure all grounds are connected. I hope you are powering the LEDs from an external power supply and not the Arduino. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
The 74hc595 is a digital chip. All its inputs are digital. All its outputs are digital. There is no point connecting any of its pins to A0.
What are you trying to achieve?
The analog pin on the esp8266 is pretty lousy (I mean, it's a 160MHz microcontroller with tens of mb of ram and a megabyte+ flash, with native on-chip wifi. All priced for less than a cup of coffee, counting the breakout board its mounted on - dont expect good on-chip peripherals too). I generally expect strange issues with it, and avoid using the analog pin, and use a more capable microcontroller if I need spiffy peripherals.
You're not trying to digitalRead it right? Pretty sure that doesnt work.
Tbh, heres what I usually do. I dont like writing c code that interacts with the internet, and I usually need decent peripherals. I usually load espruino (javascript interpreter, so you program in js, an easy-mode language) onto the esp8266, and slap together all the web stuff in js. And I pair it with an avr (talking over serial), and have the two communicate over serial, and do everything else on the avr. But this may seem easier to me because I'm very comfortable with all the relevant technologies.