NodeMCU SPI Module too fast

yamadanao · 2017-06-30 08:50

I really want to make use of the SPI module on my NodeMCU. SPI keeps my code clean and frees up some of my GPIO pins. I feel it is sending data too fast for my 74HC595 to keep up with. It was working for a bit, then stopped.

It seemed like there was a lot of noise on the line so I hooked up the logic analyzer and saw that when I was sending data, bits were flying across the line at almost 6 ns (which is awesome). I am driving a 595 and ultimately a stepper, that need data at a way slower rate. I have tried using the clock parameter in the setup call, I feel it never slows the SPI clock.

Here is the datesheet of 74hc595

Is there any way to set the clock speed to something that would be more 595+stepper friendly?

ModEdit: Moved to General category

JonnyMac · 2017-07-07 02:26

You realize, of course, that NodeMCU is NOT a Parallax product. Right?

KeithE · 2017-07-08 00:33

I guess it's possible that yamadanao is loading code onto the Parallax WX ESP8266 WiFi Module? I would look into something like SPI.setFrequency([frequency])

JonM · 2017-07-08 06:36

Here is link from Instructables where someone did the same as you are asking.

https://instructables.com/id/NODEMCU-LUA-ESP8266-With-74HC595-LED-and-Matrix-Dr/

Note, they used a SN74HC595N rather than a 74HC595D as is listed in the datasheet that was posted.

NodeMCU SPI Module too fast

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