#363

[@WacKEDmaN]

another great, informative, and useful video.. thanks Andreas :) ...what about PSRAM pins..dont they use a few aswell?

[@AndreasSpiess]

I never used WROVER modules. But now I checked: GPIO16 and 17 are connected to the PSRAM. So they are not useable (and also not available on the outside). Two pins less :-( I will update my Excel accordingly

[@WacKEDmaN]

@@AndreasSpiess i have a few boards that use external psram..(eg esp32-cam)..and the pins are exposed as you can turn the PSRAM on and off

[@michaelbishton9439]

I really appreciate your effort to count down which pins can be used for what purpose. Then, near the end, you list the services that can use any pin. Watching this as a newbee, did i misunderstand something? Did you mean any of the actually usable ones or "any pin?"

[@AndreasSpiess]

Of course only with restrictions, for example an input only pin cannot be used as an output.

[@gusercarra]

@@AndreasSpiess Please, I can´t find the excel archive... I´m trying to use an ESP32S3WROOM1 in a nodemcu

[@orparga140]

Maybe the most useful video about ESP-32. You have saved a lot of hours of our lives... 10 hours saved * 1500 vievers( at this moment) = 1'7 years of work

[@orparga140]

5,13 years of work if we calculate 8hours/day

[@AndreasSpiess]

In the end i expect manybe 50'000 viewers ;-)

[@muflah]

I learned this the hard way. It took me about 2/3 days to test all of these and verify my findings with the datasheet and other sources.

[@TD-er]

@@AndreasSpiess Yeah, but as the numbers increase, you may reach users that would never have thought of working with the ESP32 and now they will... So not sure if that still counts as "hours saved" :)

[@ksenyxths]

@@AndreasSpiess 88,223 viewers. I'm a returning viewer, and watch all the video as I'm working on an ESP32 project and I didn't wrote down the pins at the first time. More time saved, as always, well done! :)

[@Designments]

Your channel is an absolute gem. No nonsense, concise, well researched videos are rare, and you consistently deliver. Thank you!

[@AndreasSpiess]

Glad you like my content!

[@deivissergio2378]

Very good, explanatory video of all I/O functions at once. Many people look for something like this. I own a Company in Germany, and we use the ESP32 in one of our products (IoT devices)... and we use the Internal Hall sensor, as a tricky "Factory Reset" feature. When we finish with all the tests, before send to a customer, we select a "special" condition in the device, and we left the device in such as a "Magnetic bed" for a while... and this performs the "Factory Reset"... so the device is tested and ready for shipment to the customer. (I think this Hall effect sensor, is not very important, but sometimes we can have a good idea to use it... 🤔)

[@AndreasSpiess]

This is really a very good idea! I once used a reed switch with an ESP8266 for a similar purpose but forgot about it. Now I remembered.

[@paulmooij]

A great idea can you share some info? also is ESP32 good for a b2c product?

[@diydsolar]

Please share your experience, thabks.

[@deivissergio2378]

@@paulmooij Hi Paul, in my opinion, this microprocessor is a good solution, with a lot of functions... but it is necessary a lot of "checkings" "workarounds" etc.. if you are working with Arduino IDE for example... (using the tools from Espressif, is much better) Sometimes, without a reason, the processor stops, or perform self reset, etc... (of course it can be something also wrong in the code, or the libraries converted to Arduino IDE). Let's say that the predecessor (ESP8266), has better in performance and stability (and also longer in the market)... But I am happy with this new one... (I use Watchdogs to check if something goes wrong to bring the software again "on track"). Of course, we are still learning with this new processor, and I can recommend it... 👍 (in our company, we started with the ESP32 since 3 months, and already more than 50 devices installed... and no big issues up to now !!)

[@JohnBaxendale]

Thank you, this is *so* useful! I was just about to pick up an old ESP32 project and start to work out which pins to use, this will save me lots of time :)

[@AndreasSpiess]

Glad you like it!

[@rklauco]

Cool project with touch pins? My daughter has a KiwiCo box with RGB led. It was possible to turn on or off the specific colors, so you could create few colors by combination. I sneaked in the ESP32 inside, used the "switches" (removed the contact between them) and modified them to 6 touch switches. By that she can set any color she'd like - the pairs of touch buttons act as color+ and color- for specific channels :) Works quite well :D She likes it a lot. Now she has a night light with variable color.

[@AndreasSpiess]

I can imagine that a combination of colored LEDs an touch is nice for your daughter. And she can tell her friends that she has a cool father who can make such things.

[@hoodafukisalice]

This is gold for developers using ESP32. Thank you for sharing the Excel sheet Andreas.

[@AndreasSpiess]

Glad it was helpful!

[@sharpbends]

I used touch pins connected to case screws as rudimentary input device for up down back enter commands etc on GPS alarm clock :-)

[@AndreasSpiess]

Very good idea!. Hidden and no additional parts needed.

[@keen2461]

Andreas does everything I wish I had the time to do. I'm also an EE but don't have time to investigate and experiment as Andreas, so I live vicariously thru his videos.

[@AndreasSpiess]

Maybe if you become as old as I am you will have time...

[@kcmichaelm]

Excellent as always, thanks Andreas!

[@AndreasSpiess]

Thank you!

[@Thorathome]

This is incredibly helpful: identifying the ESP32 ‘safe’ pins, a little on interrupts, a bit on PWM, an intro to inline debugging. You make the ‘32 even mor fun and productive. Thank you GWTSA.

[@AndreasSpiess]

GWTSA?

[@Thorathome]

@@AndreasSpiess YOU! Guy With The Swiss Accent! (I've lived and worked all over the world, have been the Big American for ages, am Stateside now.) I value your work, am more of a software guy, have programmed computers since high school, still noodle in Arduino with ESP applications, sensors and controls. Thanks again.

[@academicpachyderm5155]

Holy cow. Thank you so much! I almost ordered my own esp32 breakout boards yesterday, but after watching this I'm definitely adding some asterisks to my silkscreen pin numbers. I'm also trying to start experimenting with the esp32-s2, so I'll be on the lookout for "gotchas" there, too.

[@AndreasSpiess]

The S2 is too new for me...

[@EmmanuelLieurain]

A very useful wrap-up, thanks

[@AndreasSpiess]

You are welcome!

[@marinehm]

I ran into these problems with my Wemos ESP8266. This is great information!! Still plenty of available of pins. Now we can use them smartly. Thanks for breaking them down to usable pins.

[@AndreasSpiess]

Glad it helps!

[@DemokratieErwacht]

Ich habe mir das Excel runtergeladen und mit deinen Kommentaren aus dem Video versehen! Danke! Das hat mir echt Arbeit gespart als ESP32-Neuling.

[@AndreasSpiess]

Gern geschehen. Das war die Idee ;-)

[@robertobrenes5283]

Tomorrow I planned to mill a PCB for a esp32 project, this video came just in time for me to check if I didn't mess things up! Thank you! Your channel is awesome :)

[@AndreasSpiess]

Very good! As said: It might save you some time to redu things...

[@robertobrenes5283]

@@AndreasSpiess RTFD has always been my motto as an electronics student so i love that you always do that!! cheers from Costa Rica!

[@tlangdon12]

It's definitely worth reviewing any design you are working to see if you have any 'input only' pins that could use pins 34 or 35. I was struggling to find enough GPIO pins for my project; I needed 12 pins, but trying to using your 12 priority pins made the routing very difficult, so I reviewed my design and found two pins that were being used for input only, so I could consider using pin 34 or 35 for them. This made the routing much easier. Thanks for your hard work to document the real situation with the ESP32 chips.

[@AndreasSpiess]

Just in our last project we forgot that pin34 is input only...

[@mcneill64]

Thank you. A bit to digest but powerful to know that 40 != 40. Saved to my list.

[@AndreasSpiess]

Glad it was helpful!

[@professorholden3104]

Excellent! I am moving my mechatronics class from esp8266 to esp32 next semester, it will also be online for pandemic reasons, so this is a great resource. Thanks!

[@AndreasSpiess]

You are welcome! Good luck with your lectures

[@paulvint]

This is great - good video, and more importantly, thanks for sharing the spreadsheet. I've been meaning to export that from the datasheet for ages, and it's a great help!

[@AndreasSpiess]

Glad it was helpful!

[@AragonDubs]

Since I discovered your channel, I am more of a maker than ever, you make it very simple, I love it, and the translations help a lot for a spanish like me. Many thanks Andreas!

[@AndreasSpiess]

Thank you. Yes, I think, Luciana, the translator does a great job!

[@U8uxa8SP]

I've been watching a lot of your videos today. Thanks for all your great information and thanks for all your production time.

[@AndreasSpiess]

Glad you like them!

[@chronobot2001]

Thanks for this. I think you may have saved me from infinite future frustration.

[@AndreasSpiess]

So I am glad :-)

[@fenixjose17]

Dear Andreas, you are an excellent teacher. Thank you.

[@AndreasSpiess]

Glad you think so!

[@G6EJD]

Also you can’t use GPIO-12 if an external pull-up is connected to it, say for a sensor, as it prevents the ESP32 from booting and causes a flash error.

[@AndreasSpiess]

You are right! I already corrected the spreadsheet. You have an excellent channel, BTW. I am a longtime subscriber.

[@aviatorbja]

The two best esp microcontroller resources on the planet right here!

[@matthiasthiele]

"and after hours, you think, you are stupid" - been there, suffered too. Great video, thank you very much. I did use a touch port for an alarm clock without any visible buttons. Just touch the clock on the top to switch off the alarm. The user interface for setting the alarm time is via a web page on the smartphone.

[@AndreasSpiess]

Nice idea! Thank you.

[@krukhlis]

You are extremely patient man! ;) But yes, this is golden gem, a treasure that every ESP32 developer needs. Thank you for this great work!

[@AndreasSpiess]

You are welcome!

[@JulianGrammer]

Yet another highly informative video. Thank you. I couldn't stop laughing at so few pins available for general programming when comparing with your video #159 at 1:40. Amazing what one can learn in three years.

[@AndreasSpiess]

Not general purpose does not mean not useable. It just means: Pay attention!

[@jwracingteam]

Andreas is a great mentor :)

[@AndreasSpiess]

Thank you!

[@Kalandro99]

I'm working on a project with 15 digital Inputs, 3 digital outputs and 1 PWM output. It's a nightmare to find reliable sources on that topic! Thank you very much Andreas! I really appreciate your research!

[@AndreasSpiess]

A lot of pins! I hope you have enough on the ESP32...

[@foxtrotbravo1744]

I found the spreadsheet useful, thanks. Frank

[@AndreasSpiess]

Glad it was helpful!

[@frollard]

Amazingly useful! I recently started porting an old project over to ESP32, and was pulling my hair out constantly having tried to just use a pinout map showing which pin went where - there was no mention of any traps or gotchas. The code wouldn't boot and I spent hours thinking my code wasn't compatible with an arduino compatible board. Truly frustrating. This is gonna save me so much time!

[@AndreasSpiess]

You are probably not the first and lot the last loosing lots of time with this. Thanks for your feedback!

[@charlesmagill4932]

"after hours, you think you are stupid" that's me. Thank you for this video. I was about to throw out my esp-32 and go back to AVR.

[@AndreasSpiess]

That would have been a big mistake 😉

[@TobiasStanzel]

Hi Andreas, I am not sure if it ws in this video or another one where you mentioned that you are still on the search for a real world use case for the Touch pins of the esp32. If you are interested, I created a smart control for my home assistant environment based on a esp32 leveraging the touch pins, took me a while to get them really working but quite happy with the end result and would be happy to share. I used some paper fastens / split pins as buttons (Büroklammer for us german speaking guys) works quite well, only recommend to use a metall chassis that is grounded ;)

[@AndreasSpiess]

Thank you for sharing your project! It looks like something useful and obviously it works.

[@marcdraco2189]

That's an amazing amount of information Andreas - must have taken you hours to compile this Thank you so much. I'm glad you questioned the hall sensor. I was similarly baffled about that because the sensitivity is so poor. It looks like the sensor needs an amplifier that's not fitted (unless it's wired internally somewhere that the manufacturer hasn't told us about). All that said, I'm still working on an Uno, learning to squeeze every last drop of performance out of an 8-bit machine

[@AndreasSpiess]

I love the ESP chips because most of my projects use Wi-Fi. For other projects I usually use other boards (currently a Morse keyer with an Arduino Nano)

[@marcdraco2189]

@@AndreasSpiess Yeah, I really need to finish off my current project and learn more about IOT - ironically, the current thermohygrometer could benefit from remote stations too. Still finish one thing before I start another or you know how that ends...

[@wilfredosandovaldelgado3690]

I have use GPIO 0 and there is no problem, thanks for the secrets.

[@AndreasSpiess]

If it stays high during boot there is no problem...

[@wilfredosandovaldelgado3690]

@@AndreasSpiess sorry Andreas, maybe I was not rigth, I wanted yo say, that in My proyect, I am ussing the GPIO 0 to activate a triac whit a low signal and there is no problem. Till the moment, by the way thanks for the tutorial with structs for RTOS programing, I have to say, that Open My mind to do some more elegant, I'm not programer, just a dreamer. Don't speak English, but try to, jejej. I'm from Colombia and thanks to You and others i'm breaking the wall of knowledge, thank you for so much.

[@liama23]

Thank you! You saved me a lot of stressfull time.

[@AndreasSpiess]

Glad I could help!

[@rudolfhaller7224]

andreas wears a "Zimmermanns-Hut" , which is an very important skill to finish a house as a carpenter. but he deserves a "Krone" , because he is the king of ESP-kingdom, and should wear a crown. gruss aus östereich rudi

[@AndreasSpiess]

Thank you very much! (My father was a carpenter)

[@rudolfhaller7224]

@@AndreasSpiess at video 4:40 you mention I2C but showing I2S can we soon expect an I2S lesson with MX98357 esp32_audio ? danke rudi

[@rigfix]

Thanks Andreas ! Another excellent video. The timing could not be better, I needed to disable the startup log on a project here :)

[@AndreasSpiess]

You are the first I hear that he needs it :-)

[@luisgarrido2166]

I'm glad to have found tour channel! Thank you very much for being such a special guide in this matter.

[@AndreasSpiess]

Welcome aboard the channel!

[@nikanetique]

I discovered many unknown things about ESP32. thank you for convenient table! 👍

[@AndreasSpiess]

Great to hear!

[@progmatica1608]

Great channel! Thanks for sharing knowledge!

[@AndreasSpiess]

You are welcome!

[@rodstartube]

As always very usefull. I will print a T-shirt with that excel file so i have it handy.

[@AndreasSpiess]

:-))

[@randomname3894]

37 and 38 are Input pins, but not broken out on the shielded modules. On the TTGO Display for example, they are useable like the other Input pins.

[@AndreasSpiess]

You are right. The WROOM module has no such GPIO pins. Only if you use the chip itself you can use these pins.

[@guidobonelli3394]

this is really great. Nice work!

[@AndreasSpiess]

Glad you think so!

[@crckdns]

Eine sehr schöne Übersicht und Erklärung! Und danke für die Excel Datei, die ist sehr nützlich.

[@AndreasSpiess]

Bitte, gern geschehen. Teilen im digitalen Zeitalter kostet ja nichts mehr...

[@lemd49]

Many thanks Andreas, you are saving us a mountain of troubleshooting hours with this guide!

[@AndreasSpiess]

Glad to help!

[@rsabear1]

I love ESP32 projects. In the last couple of days, I am measuring currents and voltages for solar calculations( I have reviewed your previous videos). I am looking to buy a PC based USB type Volt/Amp meter which will allow me to measure multiple voltages (3.3V and 5V) and currents (0-500mA), say 5 each, log the results at time intervals for later data analysis, please keep in mind when you scout the online electronics markets. Keep up the great work - this must be one of the best resources on the internet, students studying electronic engineering now don't know how lucky they are.

[@AndreasSpiess]

Good luck with your projects! And have an eye on ground when you measure voltage and current!

[@KSITREVS]

I just designed a pcb with the ESP32 chip, sadly i didn't watch it in time as i have a ADC input on GPIO2. I guess the only problem is programming the chip.... Thank you, I too found that some pins were acting up and didn't have the courage to read the datasheet, i just changed pins!

[@AndreasSpiess]

I am glad you have the information to check your design before ordering it...

[@bluegizmo1983]

Great video! I was just working on a project the other day that used a buzzer and it wasn't working properly, and I just went back to the sketch and looked. Sure enough, I had set my buzzer output to pin 39! 🤦‍♂️ Lol

[@AndreasSpiess]

S*t happens ;-)

[@mr.0x373]

such good video and a good explanation!! Thanks for saving my time!!

[@AndreasSpiess]

You are welcome!

[@pavlusa]

Super information , thank you , very informative 👍

[@AndreasSpiess]

Glad it was helpful!

[@NemonicanatLarge]

I've been working on a temperature / humidity sensor HD22 (I know I missed the designation but I'm sure you understand what I mean) and I use pin 32 as my input pin and I am glad to see its OK for this use. Thanks for the info.

[@AndreasSpiess]

Glad it works!

[@uajoku]

Excellent!!! Thank you Sir.

[@AndreasSpiess]

You are welcome!

[@MrBobman49]

I know MTDI or GPIO12 isn't in your Priority List, but this pin can be a real "GOTCHA". I was using this with an Optocoupler and a 10K pullup resistor and thought I had "Bricked" the Dev Board. Upon further examination, if you tie a pullup to GPIO12 during boot, it tells the CPU to run at 1.8V which doesn't let it talk to the Onboard Flash running at 3.3V. Now, with any design I stay off the Strapping Pins!

[@AndreasSpiess]

You are right. Now I included it in the Excel sheet.

[@batica81]

Thank you very much for this useful video! I tried porting a project (morserino 32) to a different version of esp32 board and it was very tedious (and unsuccessful) because of all the pin differences. It also uses those capacitive touch pins which adds to complexity. Maybe I will try again now :)

[@AndreasSpiess]

Interesting project. Maybe I will also build one.. Currently I build an K3NG Arduino CW Keyer because my IC-7300 only supports Iambic Mode B and I am used to mode A :-(

[@asiw]

So incredibly useful.

[@AndreasSpiess]

Glad you think so!

[@stephang5671]

Hi Andreas VERY useful again, thank you. I'd appreciated also a final 'prio 1 list' or if you marked them in the xls.

[@AndreasSpiess]

They are marked, I think (named true GPIO)

[@rklauco]

The part about GPIO0 and 2 is something I needed 3 months ago when I was doing my LCD clock project :( Thanks - better late than never :)

[@AndreasSpiess]

Maybe you need other tricks later on. I use this excel quite a lot.

[@MrKoval-nm9ky]

very good video, thank you. This week, I spent around 3 days thinking why my RTC GPIO pins were not working, and actually the GPIO 39 is Input only (of course I found it on datasheet), as you said... But I thought I was doing something wrong with ULP instructions...

[@AndreasSpiess]

You are not alone. This is the reason for the spreadsheet and the video...

[@YoutubeBorkedMyOldHandle_why]

Good call with your comment about the built in Hall sensor. This was my very first thought when I first read the specs. Hall sensors are very useful, and incredibly cheap, but will necessarily be located far away, since you wouldn't want to have strong magnetic pulses close to your uController. There are different types of sensors as well. So ... why build one in?

[@AndreasSpiess]

So we agree. One viewer used the sensor to trigger a test modus at the end of manufacturing. I found this a good idea.

[@prvashisht]

Thank you so much! I spent a day trying to figure out why my code wasn't working, turns out I was using the wrong GPIO pins!

[@AndreasSpiess]

That happened to me, too. This is the reason for this sheet ;-)

[@antoniofiolbonnin]

Some pins are pulled up or down by default at boot time. Typically not an issue if you use those for inputs, but if you use them as output you may get glitches during boot time. Messy. I can't remember if these were part of your preferred list of 12 pins or not, as my project actually needed a lot of pins (8 PWM outputs, 8 on-off plain outputs, 2 I2C buses, 1 ADC, and I'm sure I'm even forgetting some).

[@AndreasSpiess]

I never looked into that matter. Maybe somebody adds the information to the Excel.

[@browaruspierogus2182]

ESP sdk will tell you recommended pins for needed peripherals.With examples

[@krukhlis]

The quality of ESP SDK is below grade. This is the last thing I will trust. Even Devil deserves more trust than ESP SDK.

[@AndreasSpiess]

I never used the SDK. Thanks for the tip!

[@HVICTORI1]

Thankyou Mr. Andreas. Can you help us with something like "#3XX How to use an SFP interface with ESP32 o STM32" or something else.

[@AndreasSpiess]

I do not know anything about SFP. But I found this: www.reddit.com/r/esp32/comments/hdxugi/esp32_sfp/

[@TheDiverJim]

Thank you for a great video! Saving this to a playlist

[@AndreasSpiess]

Glad it was helpful!

[@TheDiverJim]

@@AndreasSpiess sir, your videos on the whole are absolutely fantastic. I’ve just started using the ESP, I would be struggling far more without you.

[@bartdemeulmeester4662]

Thanks, this will be a great reference video!

[@AndreasSpiess]

Glad it was helpful!

[@mattantonelli4273]

just generous great research

[@AndreasSpiess]

:-)

[@rodmcmahon4829]

IO14 This IO goes to about 2.4V when you are in download bot mode. I use this on my naked designs to easily show that I am in download mode by putting an LED on it, dims when in download state

[@AndreasSpiess]

Cool. Thanks!

[@Chaser185]

Excellent video.

[@AndreasSpiess]

Glad you liked it!

[@Cdswjp]

You’re awesome my friend

[@Cdswjp]

And appreciated

[@AndreasSpiess]

Thank you!

[@slacky00]

Can you make one for the old Esp8266 too?

[@TD-er]

The ESP8266 is well described in a number of blog posts. See the links mentioned here: espeasy.readthedocs.io/en/latest/Reference/GPIO.html#best-pins-to-use-on-esp8266 What makes it even harder on the ESP8266 is that some pins also toggle at boot, which makes them unusable for switching things (e.g. a relais) unless you add some filter over them to filter out the very short pulses.

[@Rob_III]

@@TD-er Thanks for the link! Though a video by Andreas on the topic would be appreciated anyway!

[@nf8002]

Thanks so much for this info please can you tell us which pins are good to use them when using can bus protocol thanks in avance

[@AndreasSpiess]

www.iotsharing.com/2017/09/how-to-use-arduino-esp32-can-interface.html

[@mafketeltje1988]

Can't resist, finally found the question the guy with Swiz accent doesn't have answer to.....hint: @1:44 thanks for the great content again Andreas,

[@AndreasSpiess]

:-)

[@sunshinelabz]

Very useful video... Looking forward for more cool tech videos

[@AndreasSpiess]

Should come. It is what I can ;-)

[@awebuser5914]

Some of the ADC channels are marked as "red" in the spreadsheet, but there's no explanation. Also, it might be better to graduate the colours from red to orange to yellow for pins that are usable, but with minor caveats.

[@AndreasSpiess]

The red ADCs are not available when you use WiFi

[@deankq4adj125]

Excellent information, thanks for sharing!

[@AndreasSpiess]

Glad it was helpful!

[@peter.stimpel]

when I purchased my very first esp32, I was quite in Arduino nano before. The first steps with esp32 were so confusing. Often you stick with an idea, but cannot get it work because of a secondary use of the selected pin. I wish I had such an excel at that time...instead I have a few more gray hair from it. For inputs, I started using I2C connected expanders. Many pins, and no hassle with double function ...

[@AndreasSpiess]

If you stick to the „save“ pins it should work. I never needed port extenders as far because I always had enough pins. But you never know...

[@thomasrounds3247]

Great information, Thank you. Concerning the touch pins, I recently was interested in using the ESP32 to measure capacitance of an external circuit for low cost liquid level sensing. We only need a single sensor pin but which one to use? So, I checked out the pins that are available using an Adafruit ESP32 Huzzah32 module; I checked with both the Feather and the simpler Breakout modules and these gave similar results. The test showed that the resting count value is different on the different pins. This may indicate different parasitic capacitances due to module routing and also leakage currents due to different pin functions. Without any added capacitance count values ranged from about 125 (Touch T6 and T7) to as low as 77 (Touch T8 and T9). Using a number of fixed 10pF capacitors I was able to show a logarithmic relationship of count to capacitance. That is, Capacitance plotted on a logarithmic scale versus count on linear scale is nearly a straight line. This makes some sense since the method is based on capacitor charge/discharge cycles and therefore based on the time-constants of such a circuit. Capacitance in the range of up to about 100pF is possible. I'm sure this is not precise capacitance for general use but it may be useful in an application such as liquid level sensing as we are investigating. Of course there are better choices for more accurate capacitance sensing but for low cost and ease of use, combined with Bluetooth, this seems like a good solution.

[@AndreasSpiess]

Good work. My question is more: What would be a cool application of your findings?

[@thomasrounds3247]

@@AndreasSpiess Application might be to sense presence of water in a container or a pipe instead of air. It could possibly be used for crude level sensing of water in a tank. I did see some hacks using the ESP32 to sense water level using resistance but that is dependent on conductivity of water, which varies, and can corrode. Capacitance sensing depends on dielectric constant of water which should be more stable and does not require direct contact.

[@derisis13]

What about I2S? I know that in the STM32F405 it can be mapped to pins where SPI can be mapped, but what about the ESP32? It is a really handy high-speed shift register and by the way a common audio protocol...

[@AndreasSpiess]

I never used I2S, so I do not know.

[@boieperez3768]

what a great video thanks for sharing

[@AndreasSpiess]

You are welcome!

[@eransimoni2249]

Hi Andreas, thanks a lot for your great video, I learned a lot from you - do you have a tutorial how to make LittelFS run on ESP32 step by step (not ESP8266) from PlatformIO, I don't see any video for it on the network

[@AndreasSpiess]

No, I never did a video on LittleFS

[@purplespower9730]

Oops! I tried to use gpio34 pin on my Lora esp32 board. did i mess up?

[@AndreasSpiess]

You decide with the info in the video

[@TestTest-si3eq]

the 8 hidden GPIO pins exist on ESP32 chip, but there pyhsical pad do not link out to the real world. I find the usefull to use for patching internal links between builtin perpherials. There are also spare links in GPIO matrix that are not connected to any builtin perpherial, these can also be used to patch and link. ie. signal228_out, Note that inturrupts on GPIO is slowed because they share same inturrput, if you use a dedicated inturrupt, say MCPWM Sync input your find they are very fast response, nSes, caused me issues because they respond to rapidly as GPIO inputs have no hystrises on them so trigger many times on reasonable fast input pulse from a transitor, similar with ADC is noisy but that because its fast, just have to oversample and average to get steady readings, aka not linear though, i use 3 resistors and capactor for ADC inputs, the extra resistor going to 3v3 to give a plus offset(0.3V so in linear area) so ADC can read small DC signals. I find the ESP32 is like a patchable PCB. Also not onboad Flash is not reliable for saving constantly settings, use external EEPROM or Flash, I had many ESP32 corrupt boot memory if there is a power fluxation, have to reload progam to flash to restore bricked device ;) Thanks for videos, hope that helps.

[@AndreasSpiess]

Thank you for your additions. So far I was lucky with my flash. Maybe because I do not power-cycle my ESPs too often...

[@RandomPerson494-12c]

Does Bluetooth/BLE occupy any pins like in case of Wi-Fi ?

[@AndreasSpiess]

Wi-Fi and BLE use the same radio.

[@RWB123]

Excellent video 📹

[@AndreasSpiess]

Thank you!

[@mvadu]

I have had hours struggling with trying to use gpio12 (on a Doit board they are next to power). Gpio12 needs to be held low during boot. With external pull up for i2c esp doesn't boot anymore. Specifically gpio12 controls the internal regulator voltage for spi flash chip. Wroom uses a 3.3v flash, and holding gpio12 high during boot sets the voltage to 1.8v. Thus flas won't work.

[@AndreasSpiess]

You are right. Thank you. I updated the Excel accordingly!

[@ndgoh67]

Thank you... Thank you for the excel sheet...

[@AndreasSpiess]

You are welcome

[@bradstewart2024]

I think most of the pins are available as GPIO's with the new ESP32-S3. And more are available.

[@AndreasSpiess]

Maybe we will need a similar chart for the S3 (and other newer ESP chips)

[@bradstewart2024]

@@AndreasSpiess Yes, may be a good idea. It seems to be more of a standard. All GPIOs are input and output. And there are more pins ("we want more").

[@muflah]

About the touch pins, they're most certainly not worth trying in a commercial project. The sensitivity is low (try putting the conductor just behind a 4mm acrylic sheet) and there is a lot of noise.

[@AndreasSpiess]

Thank you for sharing your experience!

[@bluegizmo1983]

What ESP32 board is that in the top left corner at 0:14? It's tiny with two rows of pins on each side of the ESP32 chip. It looks almost like a the ESP32 variants of the Wemos D1 Mini, but slightly smaller.

[@AndreasSpiess]

My favorite project board in the video links

[@akhurash]

Great video. I like to start using the ESP32, this video is helpful.

[@AndreasSpiess]

Glad you enjoyed it!

[@marinehm]

What are you using to program your ESP32? I’ve had 2 chips that were knock-offs and didn’t work. Now I’m getting another from Espressifs LOLIN store on AliExpress.

[@AndreasSpiess]

I use the Arduino IDE. And so far I never saw knock-offs.

[@WooShell]

".. and who doesn't use WiFi on their ESP?!" - oh, only those weird Swiss engineers with their Ethernet connected ESPs... ;-) Regarding the Hall sensor - what exactly are you expecting to see on your oscilloscope? The Hall function is multiplexed on those pins and can not be read from outside, but simply piping the output from a hallRead(); to the serial output should show a significant change when you put the magnet near the shielding can.

[@AndreasSpiess]

You are right. It shows a change, but only if you are very close to the chip. This is where I see the limitation.

[@Hossein_Ash]

Thank you

[@AndreasSpiess]

You're welcome!

[@laurencemunro]

Brilliant video, now I only need to memorise it... 😁

[@AndreasSpiess]

Very good! No new crazy tours in SA?

[@richleyden6839]

Thank you for the great research. I only had a vague notion that some pins were special.

[@AndreasSpiess]

You are welcome! Now you know a little more...

[@Sixthflyer]

Very very useful, thank you so much

[@AndreasSpiess]

Glad it was helpful!

[@Banzo-AAA]

OHHH My god, This is exactly what i needed. I have one question though. is it required to have an external clock oscillator for the chip to function! i have to use it for a college project still new to this i usually just use breadboards >however, now we have to make a pcb and I wasn't able to find the answer else where. and if I am planning to mount the esp with the code uploaded should i just wire IO0 to +3V3 or still need a pull up circuit.? Thank you so much! Awesome content!

[@AndreasSpiess]

The WROOM and WROVER modules doe not need an external clock oscillator.

[@Banzo-AAA]

@@AndreasSpiess Thank you for the reply!

[@jenniferw8963]

GPIO6 - GPIO11 -- External Flash. I ordered the ESP32 S3.. so are these pins tied up or free? I didn't realize we get so few pins.. seemed like a lot at first lol. My project needs a lot of pins.. 13 pins for push buttons and rotary encoders.. a dozen pins for PWM writes to LED for DIY Vactrols. And 2 pins for I2C to MCP23017 to drive a dozeen 10ma reed relays.

[@AndreasSpiess]

Maybe you search for "port extenders"? You find the pin assignment of the S3 in its data sheet. So far, I have no excel sheet.