The previous series of articles about UART was initially motivated by an error I was getting when using the ESP-Prog. I could have jumped straight to the conclusion, but I took the time to really understand what was going on, and we are finally reaching the end of this investigation. Connecting to “real” UART again … Continue reading The serial TX path seems to be down →| Quentin Santos
Getting Started| docs.espressif.com
The mystery In the previous article, I briefly mentioned a slight difference between the ESP-Prog and the reproduced circuit, when it comes to EN: Focusing on EN, it looks like the voltage level goes back to 3.3V much faster on the ESP-Prog than on the breadboard circuit. The grid is horizontally spaced at 2ms, so … Continue reading Transistors in reverse and redundant circuits →| Quentin Santos
In the previous article, we peeked at the reset circuit of ESP-Prog with an oscilloscope, and reproduced it with basic components. We observed that it did not behave quite as expected. In this article, we’ll look into the missing pieces. An incomplete circuit For a hint, we’ll first look a bit more closely at the … Continue reading The missing part of Espressif’s reset circuit→ The post The missing part of Espressif’s reset circuit appeared first on Quentin Santos.| Quentin Santos
I recently discussed how Espressif implements automatic reset, a feature that lets users easily update the code on an Espressif microcontroller. There are actually more subtleties than a quick look would suggest, and I spent a fair bit of time investigating them. This article and the next two present (The missing part of Espressif’s reset … Continue reading Reproducing Espressif’s reset circuit →| Quentin Santos
RST defaults to high This is an addendum to the article about Espressif’s automatic reset. In that article, we observed the effect of the RST pin on the ESP32-S2-Saola-1RI board: I skipped over this topic quickly, so I am now taking the time to explain how the RST pin manages to have a defined behavior … Continue reading The ESP32-S2 reset pin→ The post The ESP32-S2 reset pin appeared first on Quentin Santos.| Quentin Santos
In my article about Espressif’s Automatic Reset, I briefly showed UART output from the bootloader, but did not go in more details. In this article, I want to go just a bit further, by showing some two-way interactions. We’ll use the initial basic “real” UART setup. Note that I did not connect DTR/RTS to RST/IO0. … Continue reading Talking to Espressif’s Bootloader →| Quentin Santos
In previous articles, we saw how to use “real” UART, and looked into the trick used by Arduino to automatically reset boards when uploading firmware. Today, we’ll look into how Espressif does something similar, using even more tricks. “Real” UART on the Saola As usual, let’s first simply connect the UART adapter. Again, we connect … Continue reading Espressif’s Automatic Reset→ The post Espressif’s Automatic Reset appeared first on Quentin Santos.| Quentin Santos
In my previous article, I explained how Arduino makes the life of its users easier by automatically resetting the board when the UART pin DTR (or RTS) transitions from electrically high to low. This exploits the fact that this transition happens automatically when someone or something opens the serial device on the host. That is, … Continue reading Linux always toggles DTR & RTS→ The post Linux always toggles DTR & RTS appeared first on Quentin Santos.| Quentin Santos
As mentioned in my previous article, I am planning to publish a long-form article on UART. I am doing a series of shorter articles to lay the groundwork. This is one of these “short” articles; this one about how Arduino uses UART. Of course, I still went way too deep in this topic for something … Continue reading Arduino’s Automatic Reset →| Quentin Santos
Related articles| wiki.archlinux.org