Help with ESP32 using tri-state interface

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Joined: Sat Jun 02, 2018 5:53 am

Help with ESP32 using tri-state interface

Postby CGMarsh » Sat Jun 02, 2018 7:06 am

Hi folks. I am new here and reasonably new to this ESP32 stuff. I have and Arduino that is currently running an analogue chain and want to operate it via WiFi, so I need a tri-state interface between the ESP32 and Arduino. Before you ask, I don't have access to the Arduino source code, so I am unable to set up an ESP32 or any other WiFi device. I currently have the ESP WiFi connecting and operating 6 LED's that represent the 6 steps in the chain, all good. I thought that I could use a 74HCT125 as the tri-state device. This satisfies the 2 main issues. 1. It can level shift from 3v3 to 5v and 2. It leaves the output in a tri-state condition when unused.
I find that I can operate the analogue chain via the 74HCT125, no problems. When I put them together (at this stage with no computer connected to monitor for brownouts etc) the ESP32 will not even start up. It transpires that the connection between GPIO's and Enables of the 74HCT125 are causing the issue. I tried the setup using Tina and it works, although the Enable Not pin could only work using a very low value of pull-up (470 ohm), curious I thought.
My question to the Knowledge Base is, "Has anyone tried something like this before? If so any ideas"?
Thanks in advance, Colin.

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