6 ms·

Why Did These LEDs Light Up? ESP32-S3 – Which Pins Are Safe to Use? [video]

85 points by iamflimflam1 3y ago

girvo 3y ago
It's genuinely interesting that he says that the USB flashing can't be relied on: we've been using the S3 at work for... gosh, 12 months? Longer? And it's been perfectly reliable for us -- and that's despite us flashing it via OpenOCD inside a Docker container, inside WSL2 with usbipd!
- spiritplumber 3y ago
  .... literally how?
  - girvo 3y ago
    ESP-IDF devcontainer + vscode and the ESP-IDF plugin? Maybe it's worth me seeing if work will let me publish our docs around it, but it was pretty much as simple as following the ESP-IDF plugin's own documentation: https://github.com/espressif/vscode-esp-idf-extension/blob/master/docs/tutorial/using-docker-container.md https://github.com/espressif/vscode-esp-idf-extension/blob/m... The Rube-Goldbergy-ness of it all still makes me upset, but hey it works, and surprisingly well. Including JTAG debugging and all, too.
  - fotta 3y ago
    I’m using an s3 with esphome which uses platformio which uses esp-idf and it usb flashes fine too.
    - MPSimmons 3y ago
      I'm interested in what other people are doing with esphome. I am using pretty cheap 8266es to do distributed sensing around the house, but what are you doing that requires the S3? It was my impression that it was decently more expensive?
      - fotta 3y ago
        Nothing in particular that requires an S3. I’m just running a Bluetooth proxy for home assistant, which can run on a basic esp32.
      - girvo 3y ago
        The one thing the S3 has that others don't is the LX7 micro, and it's vector extensions. This can be used to speed up computer vision tasks if you're using presence detection... but really theres better choices for that haha
- Sprite_tm 3y ago
  Espressif dev here. I usually advise people to break out GPIO0 (or GPIO9 for the ESP32Cx series) because 1. if you somehow write firmware that reconfigures the USB pins, there's no way to get the USB connection going via which you can reset the ESP into download mode, and 2. if somehow a firmware upload aborts halfway, the ESP32 can go into a bootloop with the USB device periodically disappearing. In the 2nd scenario, it's not impossible to time your flash so it goes through, but simply pulling GPIO0 low is easier. I don't think having an actual button is needed, but I'd certainly have a test point or another way you can ground that pin when you get yourself in a pickle.
  - girvo 3y ago
    Oh, we absolutely have on our boards. It's just we've had to use it to recover from a borked flash maybe twice, total? We don't have a button, just have to bridge some pads.
brotchie 3y ago
Bit on strapping pins gives my nightmares. Lost tens of hours of my life trying to bring a new ESP32-based board up. Debugging code, cutting traces and soldering bridge wires, buying and using a logic analyzer. Turns out: Some of the pins on the ESP32 a) Are strapping pins (configure stuff like what voltage to talk to FLASH). Luckily there's a few fuses you can blow to hardcode some of the settings the strapping pins are reading, so they ignore logic level on boot, b) Default back to JTAG pins. For example, you have to explicitly reset GPIO12 - gpio_reset_pin(GPIO12) to use it as an I/O pin again (this burnt a day of my life). Lesson learnt, if something weird is happening with your micro, check for strapping and / or default pin behavior.
- rightbyte 3y ago
  Ye pins on those are used for many different things. Really annoying. I had the same one-day-issue. "Solved" it by quickly removing the programmer after booting and connect my uart device ...
- roland35 3y ago
  Same deal with Kinetis and ST micros - there are a few BOOT pins which can really ruin your day! They are documented but it isn't super obvious. I found that it is important to check a few parts of the datasheet/reference manual before using any part and designing a circuit: - What are the default states of every pin on start up? - What is the boot sequence? Is there a pin or setting to switch the boot between Flash, RAM, bootloader, etc? - Is there any built-in bootloader? How is it triggered? - What are the Flash config bytes/fuse settings?
evgpbfhnr 3y ago
tl;dw https://github.com/atomic14/esp32-s3-pinouts https://github.com/atomic14/esp32-s3-pinouts (I didn't watch to the end either as I hate video format for this kind of things, sorry if there was more)
zamalek 3y ago
I have found the ESP32-C3 pretty frustrating in terms of occupied pins, once you eliminate all the strapping pins etc. there aren't all that many remaining.
- benj111 3y ago
  >strapping Bootstrapping? Is that a hardware people thing?
  - numpad0 3y ago
    Strapping in circuits is figuratively tying a thing by strings so it stays in vicinity of voltage/current/circuit constants. In this case, the chip has pins that can be used to change operating modes by strapping high or low, called strapping pins. Similar to but slightly different from pull-up/pull-down. Boot strapping in circuits usually refers to passive parts that provide power needed locally for switching parts.
    - benj111 3y ago
      >Similar to but slightly different from pull-up/pull-down In what way? I've only ever come across pull up and pull down. Edit: Wikipedia seems to equate strapping with setting a jumper. I can't seem to find any other references except related to esp devices.
      - CableNinja 3y ago
        Strapping pins internally have a pullup or pulldown resistor. At startup these control what state some part of the system is in, (like the example mentioned elsewhere, flash voltage). These are controllable by applying your own resistor at startup, like a normal i/o pin would be. The difference is that these pins are multipurpose. At power-on, the early bios reads the bootstrapping pins, sets its state, and then releases them to the actual OS, so that they can be used for other things (sometimes). As useful as they are, imo they are a bit problematic, because of that mixed-use state. You have to be able to setup that pin for your hardware configuration, and then during operation use it for your needs. Most of these also have an internal fuse you can burn to force the state permanently, which is where the "slightly different" comes in. The fuse sets the permanent internal pull state, so you dont have to deal with the setup phase, except, that you need to make sure anything you use that pin for in your application defaults to the state you want, as you can still externally modify that pin at power-on.
dvh 3y ago
Is it still impossible to use ADC while the wifi is on?
- iamflimflam1 3y ago
  There are two ADC units - ADC1 is fine to use with WIFi turned in.
- HankB99 3y ago
  Like this? https://github.com/HankB/BBQ-temp-publisher https://github.com/HankB/BBQ-temp-publisher
nottorp 3y ago
Haven’t worked with esp32s at this level but isn’t this stuff in their specs like any other SoC?
- TheLoafOfBread 3y ago
  Of course it is - Chapter 2.6 Strapping Pins https://www.espressif.com/sites/default/files/documentation/esp32-s3_datasheet_en.pdf https://www.espressif.com/sites/default/files/documentation/...
- iamflimflam1 3y ago
  The information is in the data sheets for the chips, the data sheets for the modules and the technical reference manuals - but it’s spread over multiple sections. Bringing everything together into one quick and easy reference is very useful.
spaintech 3y ago
I highly recommend using Forth for interactive exploration of hardware. In my opinion, C-Forth and uEForth are particularly well-suited for the ESP32. Even when I choose to develop C-based Baremetal solutions for the ESP32, Forth proves incredibly useful for quickly testing and validating my ideas. This is especially true for verifying physical wiring, as it significantly reduces the time spent troubleshooting potential errors, whether in my own work or when examining a pre-made board.
- xchip 3y ago
  why not micropython?
  - spaintech 3y ago
    I don’t know micropython enough. I know that it is substantially supported on the ESP32, which is great, but I’m not sure if it’s able to give you the HW access that Forth has, you can extend and build your own drivers on the Forth system, which is my main use case. I like to do things as bare to the metal as possible and C and forth give me that, it’s the same reason I never used the arduino framework.

85 points by iamflimflam1 3y ago

It's genuinely interesting that he says that the USB flashing can't be relied on: we've been using the S3 at work for... gosh, 12 months? Longer? And it's been perfectly reliable for us -- and that's despite us flashing it via OpenOCD inside a Docker container, inside WSL2 with usbipd!

spiritplumber 3y ago
.... literally how?
- girvo 3y ago
  ESP-IDF devcontainer + vscode and the ESP-IDF plugin? Maybe it's worth me seeing if work will let me publish our docs around it, but it was pretty much as simple as following the ESP-IDF plugin's own documentation: https://github.com/espressif/vscode-esp-idf-extension/blob/master/docs/tutorial/using-docker-container.md https://github.com/espressif/vscode-esp-idf-extension/blob/m... The Rube-Goldbergy-ness of it all still makes me upset, but hey it works, and surprisingly well. Including JTAG debugging and all, too.
- fotta 3y ago
  I’m using an s3 with esphome which uses platformio which uses esp-idf and it usb flashes fine too.
  - MPSimmons 3y ago
    I'm interested in what other people are doing with esphome. I am using pretty cheap 8266es to do distributed sensing around the house, but what are you doing that requires the S3? It was my impression that it was decently more expensive?
    - fotta 3y ago
      Nothing in particular that requires an S3. I’m just running a Bluetooth proxy for home assistant, which can run on a basic esp32.
    - girvo 3y ago
      The one thing the S3 has that others don't is the LX7 micro, and it's vector extensions. This can be used to speed up computer vision tasks if you're using presence detection... but really theres better choices for that haha
Sprite_tm 3y ago
Espressif dev here. I usually advise people to break out GPIO0 (or GPIO9 for the ESP32Cx series) because 1. if you somehow write firmware that reconfigures the USB pins, there's no way to get the USB connection going via which you can reset the ESP into download mode, and 2. if somehow a firmware upload aborts halfway, the ESP32 can go into a bootloop with the USB device periodically disappearing. In the 2nd scenario, it's not impossible to time your flash so it goes through, but simply pulling GPIO0 low is easier. I don't think having an actual button is needed, but I'd certainly have a test point or another way you can ground that pin when you get yourself in a pickle.
- girvo 3y ago
  Oh, we absolutely have on our boards. It's just we've had to use it to recover from a borked flash maybe twice, total? We don't have a button, just have to bridge some pads.

brotchie 3y ago

Bit on strapping pins gives my nightmares. Lost tens of hours of my life trying to bring a new ESP32-based board up. Debugging code, cutting traces and soldering bridge wires, buying and using a logic analyzer. Turns out: Some of the pins on the ESP32 a) Are strapping pins (configure stuff like what voltage to talk to FLASH). Luckily there's a few fuses you can blow to hardcode some of the settings the strapping pins are reading, so they ignore logic level on boot, b) Default back to JTAG pins. For example, you have to explicitly reset GPIO12 - gpio_reset_pin(GPIO12) to use it as an I/O pin again (this burnt a day of my life). Lesson learnt, if something weird is happening with your micro, check for strapping and / or default pin behavior.

rightbyte 3y ago
Ye pins on those are used for many different things. Really annoying. I had the same one-day-issue. "Solved" it by quickly removing the programmer after booting and connect my uart device ...
roland35 3y ago
Same deal with Kinetis and ST micros - there are a few BOOT pins which can really ruin your day! They are documented but it isn't super obvious. I found that it is important to check a few parts of the datasheet/reference manual before using any part and designing a circuit: - What are the default states of every pin on start up? - What is the boot sequence? Is there a pin or setting to switch the boot between Flash, RAM, bootloader, etc? - Is there any built-in bootloader? How is it triggered? - What are the Flash config bytes/fuse settings?

evgpbfhnr 3y ago

tl;dw https://github.com/atomic14/esp32-s3-pinouts https://github.com/atomic14/esp32-s3-pinouts (I didn't watch to the end either as I hate video format for this kind of things, sorry if there was more)

zamalek 3y ago

I have found the ESP32-C3 pretty frustrating in terms of occupied pins, once you eliminate all the strapping pins etc. there aren't all that many remaining.

benj111 3y ago
>strapping Bootstrapping? Is that a hardware people thing?
- numpad0 3y ago
  Strapping in circuits is figuratively tying a thing by strings so it stays in vicinity of voltage/current/circuit constants. In this case, the chip has pins that can be used to change operating modes by strapping high or low, called strapping pins. Similar to but slightly different from pull-up/pull-down. Boot strapping in circuits usually refers to passive parts that provide power needed locally for switching parts.
  - benj111 3y ago
    >Similar to but slightly different from pull-up/pull-down In what way? I've only ever come across pull up and pull down. Edit: Wikipedia seems to equate strapping with setting a jumper. I can't seem to find any other references except related to esp devices.
    - CableNinja 3y ago
      Strapping pins internally have a pullup or pulldown resistor. At startup these control what state some part of the system is in, (like the example mentioned elsewhere, flash voltage). These are controllable by applying your own resistor at startup, like a normal i/o pin would be. The difference is that these pins are multipurpose. At power-on, the early bios reads the bootstrapping pins, sets its state, and then releases them to the actual OS, so that they can be used for other things (sometimes). As useful as they are, imo they are a bit problematic, because of that mixed-use state. You have to be able to setup that pin for your hardware configuration, and then during operation use it for your needs. Most of these also have an internal fuse you can burn to force the state permanently, which is where the "slightly different" comes in. The fuse sets the permanent internal pull state, so you dont have to deal with the setup phase, except, that you need to make sure anything you use that pin for in your application defaults to the state you want, as you can still externally modify that pin at power-on.

dvh 3y ago

Is it still impossible to use ADC while the wifi is on?

iamflimflam1 3y ago
There are two ADC units - ADC1 is fine to use with WIFi turned in.
HankB99 3y ago
Like this? https://github.com/HankB/BBQ-temp-publisher https://github.com/HankB/BBQ-temp-publisher

nottorp 3y ago

Haven’t worked with esp32s at this level but isn’t this stuff in their specs like any other SoC?

TheLoafOfBread 3y ago
Of course it is - Chapter 2.6 Strapping Pins https://www.espressif.com/sites/default/files/documentation/esp32-s3_datasheet_en.pdf https://www.espressif.com/sites/default/files/documentation/...
iamflimflam1 3y ago
The information is in the data sheets for the chips, the data sheets for the modules and the technical reference manuals - but it’s spread over multiple sections. Bringing everything together into one quick and easy reference is very useful.

spaintech 3y ago

I highly recommend using Forth for interactive exploration of hardware. In my opinion, C-Forth and uEForth are particularly well-suited for the ESP32. Even when I choose to develop C-based Baremetal solutions for the ESP32, Forth proves incredibly useful for quickly testing and validating my ideas. This is especially true for verifying physical wiring, as it significantly reduces the time spent troubleshooting potential errors, whether in my own work or when examining a pre-made board.

xchip 3y ago
why not micropython?
- spaintech 3y ago
  I don’t know micropython enough. I know that it is substantially supported on the ESP32, which is great, but I’m not sure if it’s able to give you the HW access that Forth has, you can extend and build your own drivers on the Forth system, which is my main use case. I like to do things as bare to the metal as possible and C and forth give me that, it’s the same reason I never used the arduino framework.