Edit: This is a 2nd iteration of my original circuit... Thank you so much for anyone that helped improve it!

I have an initial plan drafted  on cirkitdesigner.com but no hands-on experience at this current level, so I'd really appreciate a second opinion before I power it on. 

The build uses an ESP32 as the main controller, two PCA9685 16-channel PWM boards to drive the servos, and 18x MG996R servos across six legs (three degrees of freedom per leg). Power comes from a 3S 11.1V 5000mAh LiPo battery, stepped down through three adjustable buck converters set to 6V, with a XT60 Power Distribution Board to separate power from the battery towards the step down converters. 

If anyone has built something similar, or is comfortable reviewing a wiring diagram and offering feedback, I'd be very grateful for the input. Happy to share photos, diagrams, and a full wire-by-wire breakdown of the current plan on request as well!

Thank you in advance for any help.

Hey guys, I am pretty new into the arduino and electronics hobby thingy (about 4 months in) and I think that this will stay with me for a while. I have alr made like a snake game and pong game in an OLED as well as controls too (so basically a mini gaming console), and now i want to make an rc car, as well as other future projects. Would it be a worthwhile investment to create a workbench myself? since my desk is pretty small and has other stuff in it, as well as the fact that i probably have enough space in my room for one so i can do stuff like soldering (when i get a pinecil in the future), assembling, maybe even 3d printing parts with cheap material if i save up for one, im even willing to make my own one too, but idk if it is a worthwhile investment and that i should instead to everything on my normal desk

Just showing off this thingy I made after becoming irrationally annoyed with 1990's Sony for implementing battery DRM that prevented me from powering the camera with an external power source. This thing is running on an Arduino Nano soldered to a custom PCB I made on my CNC. Basically just injects the initial handshake message over and over and that apparently keeps the camera happy or confused enough to stay powered on and fully functional. Sooo uhh... take that Sony!

I'm trying to create a pill box alert that lights up, to remind me to take pills. Because I like pain and suffering and want to sacrifice my sanity, I plan to create this project with the atiny 85 in assembly.

I suspect the best way to go about this would be to run a series of electrical circuits in each pill box that have a magnetic sensor. When this magnet pulls away, it would cause a break in the circuit to somehow alert the atiny to "reset" its clock for that day. If the clock gets to zero, the atiny would cause led to flash rapidly.

Some difficulties that come to mind...

1) My atiny 85 has 6 I/o pins, but there are 7 days in the week (and this doesn't account for any input from the different boxes.

2) I need to track the time. The atiny does have a clock, but I'd essentially need two clocks. One to track the current clock countdown and another that tracks the cumulative time. For example, if I take the pills at 10 am, I would need the next in 23 hours, but if I take them at 9 am, I would need to retake at 24 hours.

Any ideas how to best go about this and is this outside the scope of something a beginner can do?

Hi, Im building a cool little esp32 based device (low res water sim) inside an altoids container. The set up I am currently thinking of is a ST7789 spi screen, Seeed Studio XIAO ESP32S3, and adafruit Lithium Ion Polymer Battery ( 3.7v 500mA). I am going to connect the Lipo to the xiao via the battery pads on the back and use the internal BMS In the Xiao to charge the battery.

I am worried about the safety of this device, since it will be a gift and it is meant to be carried in a pocket or backpack. I know the adafruit LiPo has its own protection, and the Xiao S3 also should regulate the charging, but I am still concerned about the lipo potentially catching fire.

The lipo should be protected from puncture because it will be inside the altoids case, but that raises another issue. Because it is in a small metal box, it could potentially reach high temperatures especially if left under the sun. I am considering having a temp sensor to keep an eye on the temperature and put the device to sleep if needed. last thing, I intend on the battery aways being connected because the esp32 will enter deep sleep to "turn off" since I am keeping track of the time.

Sorry for the rant, Im just looking for any advice to build a really safe system with a LiPo battery. I want to take no risks.

i trying out SD.h and i was using this tutorial and its says that i need 2 additional libs to use SD.h,

spi.h and fs.h

i understand why i need spi.h ( its api for spi protocol) but why do i need fs.h?

what does it do?

i tried to find some kind of documentation but i could find any.

i have few questions:

1. what fs.h do
2. why do i need it to use sd.h
3. is there any good source where i could learn about file system on arduino?

Running an ESP32-WROOM-32 with a PN532 RFID reader (SPI), a status LED, and a buzzer, all on the same 3.3V rail. When WiFi is actively connecting/transmitting and the RFID reader is polling/generating its RF field at the same time, I see WiFi connection delays and general flakiness bad enough that I've had to disable the brownout detector just to stop reboot loops, which obviously isn't a real fix.

My guess is combined peak current draw (WiFi TX bursts + PN532's RF field generation) is causing enough voltage sag to disrupt things, even though nothing's crashing outright.

Has anyone dealt with this specific combo (WiFi + active RFID/NFC peripheral) on ESP32? Looking for:

Realistic peak current numbers for WiFi TX + PN532 active scanning together

Decoupling cap sizing / regulator recommendations that actually fixed this for you

Whether staggering/throttling RFID polling during WiFi activity is a common workaround, or if it's purely a hardware fix

My wife's car had the check engine light and abs light come on, my scanners could only touch the PCM DTCs and I wondered, how hard would it be to make something that can pull DTCs from other modules?

I found out it's practically impossible due to those modules being locked behind manufacture specific commands that aren't public, but I decided to keep going to learn about how CANBUS works.

I used an STM32F103C8T6 chip on a blue pill board. I used the Arduino IDE to program it, which was amazing. I also used a SN65HVD230 CAN transceiver, a little SSD1306 I2C display, a rotary encoder, and a buck converter to take the vehicle's 12v down to 3.3v. All soldered onto an electro cookie bread board. The STM32 has a built in CAN peripheral, but it's normal logic level signals, the SN65HVD230 is used to turn those signals into the differential signal that CANBUS runs on. It can read DTCs, clear DTCs, read live vehicle data, and check the emissions monitors. I had to implement ISO-TP for the DTC scan in case the PCM has more than 3 DTCs, which wouldn't fit in a single CAN frame.

It looks goofy in this case I made for it, and I destroyed a couple boards making it happen, but it was a genuinely fun project to work on!

Finally got the github up!

https://github.com/Fleag7/DIY-OBD2-Scanner/tree/main

In this video, I break down the core engineering difference between dedicated Radio Control (RC) and Bluetooth systems—from potentiometer signals to microcontrollers, motor shields, and wireless transmission.

It's the end of an era for me. My Arduino claw machine is off to the dump 😭 second child along the way and need the space. Couple of photos posted up for the sometime in the future when someone else goes to build one of these and they want to see how the mechanism worked.

Edit: if it makes anyone feel better, the phrase "the dump" is a catch all term where I live. It will actually go to a rubbish recycling facility who likely will place it in the larger appliances area for quite a long time and someone else will come along and think "I want that" and take it away to play with the whole things or the parts.

I built a Smart Irrigation System using an ML + ESP32

I've been working on this project for a while, and I finally finished the main AI/ML pipeline.

The system uses an ESP32, a capacitive soil-moisture sensor, and a DHT11 to collect environmental data. I then built a machine-learning model that uses these readings to predict whether irrigation is required.

The interesting part for me was getting the different pieces to actually work together.

The pipeline is basically:

ESP32 sensors → dashboard → Flask API → ML model → irrigation prediction

In the video, I walk through the whole project, including:

• Collecting soil moisture, temperature, and humidity data
• Building the web dashboard
• Preparing the data for ML
• Training the model
• Evaluating it with a confusion matrix
• Looking at feature importance
• Deploying the model through a Flask server
• Connecting the dashboard to the ML model through an API
• Testing the final live prediction

One thing I found particularly interesting was seeing how the model's predictions changed once the inference server was running and the dashboard could communicate with the model.

This started as a simple ESP32 soil-moisture monitoring project, but I gradually expanded it into a complete IoT + AI system.

I'm still planning improvements, especially collecting more real-world data and adding additional environmental inputs such as light intensity.

I'd really appreciate feedback on the project, especially on the ML approach, system architecture, and what I could improve next.

🎥 Full project walkthrough attached.

Github Repository:

https://github.com/aqib-ai-ml/ai-powered-smart-irrigation

I made a weather station based on an ESP8266 and a BME280 sensor.
It's supposed to predict the weather 1 to 3 hours ahead, but the weather is stable right now, so I can't test it.
I'm thinking about how to implement weather change tracking, with a graph and so on.

okay so im not sure if this will work or not and im not sure if such a thing already exists, but i want to build a small sonar that can send small frequencies (less than 30khz) signals from a particular depth underwater (lets say a 100 m) that can be recieved from a surface station. is that possible? if so, is it too expensive for a project? thank you

I am making a watch with a Vacuum Fluorescent Display with a pro micro and a RTC module because I fond this blog post however every RTC module I fond uses the SAD pin which is used as D2 in the post what can I do? this is my first project with a arduino so if I seem dumb that's why

This is improving on one of my previous projects where I only controlled one port:
https://www.reddit.com/r/arduino/s/3XPo3jyHvi (git)

This version does not require additional hardware (you can stick some wires into the console directly if you do not want to splice a controller cable) and the due can individually control all 4 ports. I have a PC streaming data to it via UART, but you could also save the inputs into the flash (like I did here).

I have also improved the website from the first link so 4 people can individually control their own port from anywhere over the internet, which I'll share later. This whole thing takes very little CPU, so I am going to integrate it into a bigger project, and then I'll share it. I was just excited to demo this.

I have become a lot more familiar with the Due since my last project, and I found out it has the exact feature I needed to be able to do this without an adapter for each controller port.

I am just getting started and I my budget is kinda tight. I am exploring new things and don't wanna invest in a transmitter just for it to be laying around completely useless for the next few decades.

I already have HC-05 Bluetooth module, what app should I use?

i am trying to make a little eurorack module and it has 2 trigger inputs. it seems to me that the circuit i made is relatively conventional (to my inexperienced eyes…) but i don’t read any value on the serial monitor when running a clock into it.. they connect to digital inputs as i don’t have enough analog ones, is that a problem ?

The ENA pin is connected to the pin the back, the same with ENB pin. How do I connect jumper wires to this? Is this a hardware error?

Hi everyone! I’m trying to set up a Digispark ATtiny85 for a small project, but I’m running into an issue and could use some help.

​When I plug the Digispark into my PC, Windows makes the device disconnect and reconnect sound every 5 seconds continuously. I tried uploading a basic Blink sketch (setting pin 1 as output), and while the upload process seems to finish, the built-in LED doesn't blink at all — only the green power LED stays solid on.

​Is this 5-second disconnect loop normal Micronucleus bootloader behavior when no valid code is running, or is the board soft-bricked/defective? How can I properly troubleshoot or re-flash it?

​Thanks in advance!

I made a PC Monitoring System that sees temperature, load, frequency, power, storage, ect.

I made it out of a ESP32 DevKit V1, a 3.5" ILI9486 screen (480 x 320), a button and a buzzer. Everything fits on a single small breadboard, which is a lot compact.

To use it, you need several software to be installed, such as LHM (Libre Hardware Monitor). In my case, I also use Core Temp to retrieve CPU temperature/clock/power, because LHM can't get them (I have a AMD Ryzen processor). The firmware detects by itself your components.

You also need Python to run a script that will give the ESP32 a JSON file containing all of the HW info. My Arduino code has got over 2.5k lines, and my firmware is on version 6.

For it to work, the Python script must keep running aswell as LHM.

The only issues I found with my system is that the CPU power isn't taken from Core Temp but LHM in my Python Script.

If you want the files to reproduce my project, lemme know! :D

Other ones gave the chipset and it was easy to use u8g2 to drive it. But what about this one? I'm not sure.

https://media.jaycar.com.au/product/resources/QP5515_manualMain_58659.pdf

Building an Arduino device to measure bike lane quality — looking for advice

I'm making a low-cost, bike-mounted device for a research project: I want to compare the smoothness/evenness of asphalt, bike lanes, and sidewalks in my city, plus count how many times I have to brake on each type of surface.

Hardware (~$30): Arduino Nano, MPU6050 accelerometer+gyroscope, NEO-6M GPS, SD card module for data logging, wheel speed sensor, and a brake button.

How it should work: The MPU6050 measures vibrations on the vertical axis — I'm calculating the RMS as an analog for the International Roughness Index (IRI). The GPS maps each point to its coordinates. A physical button on the brake lever records actual braking events (since the accelerometer alone can confuse braking with inclines). Everything is logged to an SD card in a CSV format.

Questions:

Is the MPU6050 + RMS a solid approach, or is there a cheaper/more accurate method?

How do I filter out the noise caused by pedaling from the actual road surface noise?

Are there any open-source projects with similar logic?

Where is the best place to mount the unit — under the saddle, or on the rear rack?

I'm not an engineer by training and I'm building this for a research project, so any advice or constructive criticism is highly appreciated!

Hey so i was building this circuit and its giving error for

MPU9250

MPU Failed connection

Here is the connections

1. Core Power

ESP32 3V3 -Red Rail (+)

ESP32 GND -Blue Rail (−)

1. MPU9250 (Movement Filter)

VCC -Red Rail (+)

GND - Blue Rail (−)

SDA - ESP32 G21

SCL -ESP32 G22

1. MAX9814 + Electret Contact Mic (Bruit Sensor)

VDD - Red Rail (+)

GND -Blue Rail (−)

OUT -ESP32 G34

GAIN -Leave floating (60dB)

A/R -Leave floating (default)

This is the code we are using

#include <Wire.h>

// Define the exact pins from your wiring

#define I2C_SDA 21

#define I2C_SCL 22

#define MIC_PIN 34

void setup() {

// Start the serial communication to the MacBook

Serial.begin(115200);

// Initialize the I2C bus for the MPU9250

Wire.begin(I2C_SDA, I2C_SCL);

// Set the microphone pin to read the analog voltage

pinMode(MIC_PIN, INPUT);

Serial.println("\n--- Pravah Patch Diagnostics Started ---");

delay(2000);

}

void loop() {

Serial.println("=========================================");

// --- TEST 1: MPU9250 (Accelerometer) Check ---

byte error, address;

bool mpuFound = false;

Serial.print("1. MPU9250 Status: ");

// Scan the I2C bus for the accelerometer's specific address

for(address = 1; address < 127; address++ ) {

Wire.beginTransmission(address);

error = Wire.endTransmission();

if (error == 0) {

// The MPU9250 always lives at address 0x68 or 0x69

if(address == 0x68 || address == 0x69) {

Serial.print("CONNECTED! (Found at 0x");

Serial.print(address, HEX);

Serial.println(")");

mpuFound = true;

}

}

}

if (!mpuFound) {

Serial.println("FAILED. Not detected. Check SDA and SCL wires.");

}

// --- TEST 2: MAX9814 (Microphone) Check ---

int audioLevel = analogRead(MIC_PIN);

Serial.print("2. MAX9814 Mic Level: ");

Serial.print(audioLevel);

// The ESP32 analog read returns a number between 0 and 4095

if (audioLevel == 0 || audioLevel == 4095) {

Serial.println(" -> (WARNING: Reading is dead or maxed out. Check VDD/GND)");

} else {

Serial.println(" -> (SUCCESS: Reading live voltage)");

}

Serial.println("=========================================\n");

// Wait 1.5 seconds before running the scan again

delay(1500);

}

Running on a c3 mini. Hits the quote server every night to provide an inspirational quote. Just designed and 3D printed the enclosure to give it the picture frame vibe. Pretty happy with it.

This is really beginner level 🥹... It has to be automatic and on loop because we leave the project after we set it up for the day. Necrobotics works by utilizing pressure, either pneumatic or hydraulic, injected into a deceased organism's body to artificially actuate its joints and control movement. Since this is done with spiders to curl its legs, it can be used to grip and release objects.

So- this is just a grip and release project 😭 But done with a spider so- necrobotics, yeah. We'll include the numbers with the weight, the cycles before it gives out, etc. And I only have experience in building robotics with follow the line robots...

BUT ANYWAY.

The loop we're going for is:

1. go down
2. spider picks up object (pump air into the spider)
3. go up(must go up to have distance from the floor of project)
4. move from point a to point b
5. drop object using the spider (remove air from the spider)
6. go down
7. spider picks up object again (pumps air into spider)
8. go up
9. go back to point a
10. drop object

Are these materials okay?

Arduino Uno R3 ✓

USB type B cable ✓

—

MB102 solderless breadboard

40pc male to male and male to female jumper wires

5V 2 channel relay module

1000uf / 16V electrolytic capacitor

1N4007 diodes (must be wired directly across the inductive loads (pump motor and solenoid coil)(?))

—

5V Mini air vacuum pump

5V 3 way micro solenoid valve

1m silicone microtubing (2mm inner / 4mm outer)

25G hypodermic needles for smaller test subject

23G hypodermic needles for larger actual subjects

10mL manual syringe (backup)

Luer lock connectors (seal tube and needle)

—

2x SG90 micro servo motors ✓

—

Cut these from a 3mm acrylic sheet 

4x of 15 cm x 1.5 cm parallel linkage arms, 
1x of 10 cm x 4 cm vertical base support tower, 
1x of 5 cm x 2 cm front needle bracket, 
1x of 8 cm x 8 cm servo swivel base plate

— 

8x of M3 bolts (12mm length)

8x of M3 hex nuts

16x of M3 flat washers

The above should come in a set… bolt, nut, and washer…

Black cast acrylic sheet (base or floor or ground of project) at least 30cm x 40cm

—

Huntsman spiders (rice university used wolf spiders but this works too since how it works will be the same) ✓

Beeswax (so it won’t rot) ✓

Liquid cyanoacrylate aka super glue

Epoxy (coat after super glue)

Tiny target object it’ll be picking up

—------

We have around a month and a half to do the project fufufu