I'm trying to get 74HC165 shift registers work with the shiftIn() function instead of using SPI (I'm using the SPI bus for a different set of shift registers that do something else in my setup) and there's the following strange behavior: If I use only one chip, the bits are shifted by one place to …

First a question alexandros301: I'm using the SPI bus for a different set of shift registers that do something else in my setup Any reason why you can't just use a separate latch and include them in the chain? alexandros301: If I use only one chip, the bits are shifted by one place to the le…

septillion: First a questionAny reason why you can't just use a separate latch and include them in the chain? Mainly because of the setup and long wires which have cause me issues in the past (even with setting the speed of the SPI). septillion: So you expect for example 182 and get 109? I wo…

alexandros301: Mainly because of the setup and long wires which have cause me issues in the past (even with setting the speed of the SPI). Doubt shiftIn() is really slower than SPI at it's slowest setting.... alexandros301: I'm actually receiving the serial data in Pure Data and parsing them …

septillion: Doubt shiftIn() is really slower than SPI at it's slowest setting.... I don't mind that as these shift registers will only be used at boot, only once, so speed is not an issue. septillion: Ahhhhhh, would you mind showing those calculations? Because they sound very suspicious to me…

Then show some Serial output please. Of course complemented with a picture of the settings :slight_smile: For a start I would suggest an all switches on and an all switches off dump :slight_smile: Because I see nothing wrong in code. And I know shiftIn() and a HC165 work together fine. There most …

I've attached the output of the serial monitor. I'm away from home and I have an eight-position DIP switch and two push buttons, so the first shift register has only its first and last pins connected to a switch, and the second has seven pins connected, cause pin 6 of the DIP switch is borken. On t…

Oww, might see it.... You have CLKINH/!CE floating... Tie it to GND. Never leave inputs floating...

septillion: Oww, might see it.... You have CLKINH/!CE floating... Tie it to GND. Never leave inputs floating... No it's not that, sorry, I forgot to include it in the schematic. It is tight to GND. Thanks for all the help so far!

Damn :frowning: You never ever elsewhere in the code toggle the clock pin? Aka, can you post all of the code used for the last test? And are you absolutely a 100% sure the wiring is correct? Aka, did you triple check it with a DMM?

septillion: Damn :frowning: You never ever elsewhere in the code toggle the clock pin? Aka, can you post all of the code used for the last test? And are you absolutely a 100% sure the wiring is correct? Aka, did you triple check it with a DMM? I'm not toggling the clock pin, only whatever hap…

74HC165 shift register with shiftIn() wraps last bit around the beginning

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septillion July 12, 2019, 7:58am 12

One final brain fart! Do you have bypass capacitors close to every HC165?

(And I assume it's all on a single PCB aka traces are <10cm?)

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74HC165 shift register with shiftIn() wraps last bit around the beginning

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