Setting up Arduino IDE with Heltec ESP32 module for macOS

Heltec WiFi Kit 32 ESP32 module

The Heltec WIFI Kit 32 is an interesting little module that integrates a WiFi/MCU SoC and a small OLED display on a single board. If you want to set up the Arduino IDE to work with this device and you’re on macOS, this is for you. This particular ESP32 module has a number of impressive features: 240 MHz processor speed and 4 MB of flash memory. The onboard OLED display can be conveniently used for debugging.

Install command line development tools

If you haven’t already installed the command line dev tools, you’ll need to do so.

xcode-select --install

For some reason, I had to do this twice before it would install. It eventually succeeded.

Install the Arduino support files

mkdir -p ~/Documents/Arduino/hardware/espressif
cd ~/Documents/Arduino/hardware/espressif
git clone esp32
cd esp32
git submodule update --init --recursive
cd tools

With the last command python I got an SSL error. I was able to workaround it but downloading the mkspiffs archive here. My target machine is still on 10.11, and I downloaded mkspiffs-0.2.1-osx.tar.gz. Then I just moved the archive (not unzipped) to ~/Arduino/hardware/espressif/esp32/tools/dist. Then I reran:


It still threw an error related to openssl, so I updated the Python distribution with Homebrew[1], and updated openssl:

brew install openssl
brew install python

Then I was able to run


Now you’re setup to use the Arduino IDE to develop for this powerful little board.

Heltec WiFi Kit 32 pin diagram


  1. Homebrew is an excellent package manager for macOS. It's incredibly easy to install. See the link provided.

Brutal piece by Adam Davidson about the pivotal role that the takedown of Michael Cohen plays in the unraveling of this disastrous presidency.

The narrative that will become widely understood is that Donald Trump did not sit atop a global empire. He was not an intuitive genius and tough guy who created billions of dollars of wealth through fearlessness. He had a small, sad operation, mostly run by his two oldest children and Michael Cohen, a lousy lawyer who barely keeps up the pretenses of lawyering and who now faces an avalanche of charges, from taxicab-backed bank fraud to money laundering and campaign-finance violations.

A brutal piece on Trump from the New York Times.

There are plenty of examples these days, from Moscow to Budapest, of how “democracies” can be manipulated to the point where they can yield only one result. This is Trump’s objective, and for it he needs a weakened Justice Department, a weakened press and an American public that will believe anything. He has had setbacks but is stubborn.

Trump’s toolkit is familiar. In it are the tools of every authoritarian brute everywhere. Americans are better than this, though.

Stalin, Trump, and the cult of personality


Великий Сталин — знамя дружбы народов СССР!

Great Stalin - banner of friendship of the peoples of the Soviet Union!

After reading about U.S. President Donald Trump’s “Number 1 fan”, Gene Huber, I was struck by the similarities between the adoration of Trump and that of Soviet leader, Josef Stalin. Throughout his tenure as General Secretary of the Communist Part of the Soviet Union, a cult of personality developed around Stalin. He was often called Великий Сталин (Great Stalin.) Propaganda posters depicted Stalin as a benevolent steward of the needs of the people.

A following similar to that of Stalin is emerging in the U.S. Gene Huber, a used car salesman from Florida left his business to promote Trump full-time. According to reports, Mr. Huber has a life-size cutout of Trump in his home and each day salutes the image and utters his adorations.[1]

The similarities between Trump’s cult of personality and that of Stalin could not be more striking. But history points out a difference. Stalin had a complex and possibly conflicted view of the cult surrounding him. Privately he could be quite self-deprecating. Openly, too, he wrote that the cult of adoration was inconsistent with Marxist ideals. Trump’s need for adoration, on the other hand, knows no bounds. His non-stop campaign-style rallies, held long after his election represent little more than opportunities to solicit the adoration that his cult willingly offers.

Ultimately, Krushchev came to denounce the cult of personality on Stalin’s death. But the process of de-Stalinization required considerable efforts on the part of Party leadership. How much will it take to undo Trump’s hold over his cultish following?

  1. Huber is reported to speak encouraging words to the Trump cutout: "Good morning, Mr. President. I pray for your safety today. I thank you for what you do and let's have a great day. Thank you, sir."

Implementing a simple menu interface on OLED display

While working on a project to automate environmental control in our greenhouse, I needed to implement a menu interface on a small OLED display. In this sub-project, meant to test the concept, I’ve used a Teensy 3.1, a small I2C-driven 0.96" monochrome OLED display and a rotary encoder.

Bill of materials:


This project is a proof-of-concept for using a rotary encoder to manipulate an on-screen menu of options. A number of electronics design concepts are used here.

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Carl Sagan’s “Baloney detection kit” is arguably more important now than ever. His 9 rules for critical thinking work for science and they can work to detect political baloney, too.

Arguments from authority carry little weight — “authorities” have made mistakes in the past. They will do so again in the future. Perhaps a better way to say it is that in science there are no authorities; at most, there are experts.

Question: when was the last time you heard Trump provide an evidence-based argument for anything? He relies on the argument from authority in every sphere. He deliberately seeks out people on the basis of charisma rather than expertise - the mark of an amateur.

Resetting the Syncthing index

I use Syncthing[1] to keep my laptop, desktop, and workshop computers in sync.[2] At least 99.9% of the time it works perfectly. Rarely, it seems to choke because of some edge case that I’ve never been able to sort out. But it never recovers on its own. Instead, it continues to report that a remote is 99% done syncing.

The workaround that I’ve learned is to simply reset the index. When the index gets rebuilt everything automagically works. You can’t do it via the GUI; you have to execute a REST call against the server. It took me a while to find it.

curl -X POST -H "X-API-Key: abc123" http://localhost:8384/rest/system/reset?folder=default

If you want to erase the entire index, execute the call without the folder parameter. Otherwise, provide the name of the folder. The API key isn’t abc123; it’s actually found in Actions > Settings > API key. Before executing the call, I pause syncing on both sides, rebuild the index, then start it up and let them go at it.


  1. No, there's no iOS client. I'm OK with that.

  2. Why don't I just use Dropbox like everyone else? I trust peer-to-peer syncing because I'm in control. I don't know what Dropbox is up to.