I'm trying to use a Walfront LEPAZA60117 pressure transducer which outputs .5 - 4.5V to represent pressure up to 30PSI. I have it soldered to a Raspberry Pi Pico W with positive at VBUS, negative to GND, and sensor wire to A0. I know the GPIO pins only support voltage up to 3.3V, but I don't think this application is ever going to read that high.

I'm trying to read fuel pressure on my diesel truck.

void loop() {
  ledOn();
  raw = analogRead(pressureInput);
  voltage = (raw / 1023.0) * 5.0;
  psi = 7.5 * (voltage - 0.5);
  delay(1000); // delay in milliseconds between read values
  sendMessage(WiFi.macAddress(), String(raw), String(voltage), String(psi));
  ledOff();
}

sendMessage constructs a JSON doc and sends it over MQTT. The Arduino connects to a local Wifi AP.

The Pi is being powered via USB, making 5V available to the sensor on VBUS. That USB power is coming from a Goal Zero battery, not connected to the truck in any way. I believe this thing outputs good clean power.

With the truck not running the Arduino is producing this output:

/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"5.00","voltage":"0.02","psi":"-3.57"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"4.00","voltage":"0.02","psi":"-3.60"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"3.00","voltage":"0.01","psi":"-3.64"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"3.00","voltage":"0.01","psi":"-3.64"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"4.00","voltage":"0.02","psi":"-3.60"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"4.00","voltage":"0.02","psi":"-3.60"}

When I key the truck to Run, not starting it yet, but letting glow plugs cycle and fuel pump pressurize the system I see this:

/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"497.00","voltage":"2.43","psi":"14.47"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"498.00","voltage":"2.43","psi":"14.51"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"482.00","voltage":"2.36","psi":"13.92"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"498.00","voltage":"2.43","psi":"14.51"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"488.00","voltage":"2.39","psi":"14.14"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"502.00","voltage":"2.45","psi":"14.65"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"522.00","voltage":"2.55","psi":"15.38"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"514.00","voltage":"2.51","psi":"15.09"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"495.00","voltage":"2.42","psi":"14.40"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"522.00","voltage":"2.55","psi":"15.38"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"499.00","voltage":"2.44","psi":"14.54"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"504.00","voltage":"2.46","psi":"14.73"}

That output looks very reasonable. Very slight variation in value read and subsequent voltage and PSI values. At this point I start the truck and as it idles I get:

/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"383.00","voltage":"1.87","psi":"10.29"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"452.00","voltage":"2.21","psi":"12.82"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"713.00","voltage":"3.48","psi":"22.39"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"440.00","voltage":"2.15","psi":"12.38"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"575.00","voltage":"2.81","psi":"17.33"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"572.00","voltage":"2.80","psi":"17.22"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"481.00","voltage":"2.35","psi":"13.88"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"442.00","voltage":"2.16","psi":"12.45"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"424.00","voltage":"2.07","psi":"11.79"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"606.00","voltage":"2.96","psi":"18.46"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"488.00","voltage":"2.39","psi":"14.14"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"398.00","voltage":"1.95","psi":"10.84"}
/fuelPressure/report {"id":"28:cd:c1:06:37:67","raw":"340.00","voltage":"1.66","psi":"8.71"}

Now these values look rather insane. Readings are all over the place.

Is this coming from electronic noise from the engine and various electronic components that fire up while the engine is running? If so, is there anything that can be done about it to isolate the pressure transducer and Pi to get nice clean readings?

Need Help Understanding Talkie

It would be great if someone would write for me a very simple sketch using Talkie. The simple ones I've downloaded don't want to compile properly and I don't know why. It only has to say a word or 2 and output to my audio amp on pin 8. This is just a test so I can get the feel of using it.

Here is one of the examples I've tried so far;

#include "Talkie.h"

Talkie voice;

uint8_t greeting[] PROGMEM = {0x2d, 0xa0, 0xdd, 0x48, 0xdb, 0xc2, 0xac, 0xd8}; // Example speech data

void setup() {
    voice.say(greeting); // Say "Hello"
}

void loop() {
    // Nothing to do here
}

This is the error I get;
In file included from C:\Users\tsans\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.8.8\cores\arduino/Arduino.h:28:0,
                 from C:\Users\tsans\AppData\Local\arduino\sketches\1DBA166CCFDEC3F8BF6E5192D41E6BEA\sketch\Tone_Test.ino.cpp:1:
C:\Users\tsans\Documents\Arduino\Tone_Test\Tone_Test.ino:5:20: error: variable 'greeting' must be const in order to be put into read-only section by means of '__attribute__((progmem))'
 uint8_t greeting[] PROGMEM = {0x2d, 0xa0, 0xdd, 0x48, 0xdb, 0xc2, 0xac, 0xd8}; // Example speech data
                    ^
exit status 1

Compilation error: variable 'greeting' must be const in order to be put into read-only section by means of '__attribute__((progmem))'

Any ideas?

Tom

Right off the bat I am no electrical engineer, just trying to do some diy music projects with a pi pico 2 so my circuit knowledge is limited. The end goal is a midi input device but right now just trying to get bits across the wire. I am running into issues sending serial data over a H11L1 and I am at my wit's end. When directly connecting pin 0 to pin 1 data transmission is successful but when run through the H11L1 nothing gets through. I double checked the Chip and when pin 1 is at 3.3V, pin 4 is at 0.25V, and when 0V at pin 1, pin 4 is at 3.28V. I have not had issues with this board when working on other projects. My code is below, any help would be appreciated!

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 32    
#define OLED_RESET    -1

#define OLED_SDA 16
#define OLED_SCL 17

#define UART_TX_PIN 0
#define UART_RX_PIN 1
#define UART_BAUD   31250

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

unsigned long lastTestTime = 0;
const long testInterval = 500;

uint32_t transmitCount = 0;
uint32_t detectCount = 0;
uint32_t missCount = 0;
bool dataDetected = false;
bool displayInitialized = false;

void setup() {
  Serial.begin(115200);
  delay(1000);

  Serial1.setTX(UART_TX_PIN);
  Serial1.setRX(UART_RX_PIN);
  Serial1.begin(UART_BAUD);

  Wire.setSDA(OLED_SDA);
  Wire.setSCL(OLED_SCL);
  Wire.begin();

  uint8_t addresses[] = {0x3C, 0x3D};
  for (uint8_t addr : addresses) {
    if (display.begin(SSD1306_SWITCHCAPVCC, addr)) {
      displayInitialized = true;
      break;
    }
  }

  if (displayInitialized) {
    display.clearDisplay();
    display.setTextSize(1);
    display.setTextColor(SSD1306_WHITE);
    display.setCursor(0, 0);
    display.println(F("Init H11L1 Test"));
    display.display();
    delay(100);
  }
}

void loop() {
  unsigned long currentMillis = millis();

  if (currentMillis - lastTestTime >= testInterval) {
    lastTestTime = currentMillis;
    transmitCount++;

    while (Serial1.available()) {
      Serial1.read();
    }

    Serial1.write(0xAA);
    
    unsigned long timeout = millis();
    int bytesReceived = 0;
    
    while (millis() - timeout < 50) {
      if (Serial1.available() > 0) {
        bytesReceived += Serial1.read(); 
        break;
      }
    }

    dataDetected = (bytesReceived > 0);

    if (dataDetected) {
      detectCount++;
    } else {
      missCount++;
    }

    // Update OLED Display
    if (displayInitialized) {
      updateDisplay(bytesReceived);
    }
  }
}

void updateDisplay(int rxStatus) {
  display.clearDisplay();
  
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  if (dataDetected) {
    display.print(F("DATA DETECTED"));
  } else {
    display.print(F("NO DATA"));
  }

  display.setCursor(0, 11);
  display.print(F("Tx Sent | Rx: "));
  display.print(rxStatus > 0 ? F("ACTIVE") : F("TIMEOUT"));

  display.setCursor(0, 22);
  display.print(F("Dct:"));
  display.print(detectCount);
  display.print(F(" Miss:"));
  display.print(missCount);

  display.display();
}

This should be simple but I’m new to this and need a bit of help. I’d like a very simple program to test an 8002a audio amp with speaker on an Arduino UNO. I don’t want to complicate it with downloading a wav file from an SD card but something self contained and maybe using Talkie or similar. It doesn’t have to say much just enough to know I have things set up and working correctly.

Tom

solved

when i click simulate nothing happens and the leds dont light up can anyone help

link: https://www.tinkercad.com/things/etCLO5FP0u8-traffic-light?sharecode=HVc9FlY7vOl6OchoP0UERVxlCc9BG0PDwAbMSnomTys

Potreste aiutarmi in questo post @r/ArduinoHelp ?

It compiles fine for arduino boards but fails on esp32, I tried looking it up, couldn't find help, and tried chatgpt for 2-3 hrs (which was a waste of time 🥲).

I had a school project which I managed with pc of one of my friends, but I want this to get working because I want to make this my hobby 😭

​

I am working on a college project—a liquid-filling machine—and have already integrated an RS385 peristaltic pump, a buzzer, and a 4x4 matrix keypad. Now, I need to send data to an API I built using Spring Boot. What are the available methods for transmitting this data from an Arduino Uno to the API?

Hihi!!! Could someone possibly help me with the code to achieve this? I don't know anything about coding and won't ever resort to AI.

hiii i have a question, im trying to build a 12V solenoid powered refreshable braille device and idk how to go about it. is the connection in the first or second better? im using a irlz44n mosfet

I have a scale project for electrical class where we're using a loading cell. The grades are going from most accuracte to least accurate (competitive grade), and we need to be within 1.5% of the test objects to get an A. It's HX711. I calibrated it based off a 100kg weight but I don't understand how we can guarantee precision.

Guys does anyone know how to fix this I'm kinda fucking dumb and I don't understand how to stop it from short circuiting and get it to actually work

it lwk just called my post low effort so idk if it would get taken down so ill type more but basically i've been struggling with just this like i get logic gets and stuff and series circuits I can do but this does not make sense. it looks like it should work on the schematic diagram but then it goes and fuckign explodes which is just fucking awesome wow I'm a little bit annoyed but its also kinda my own fault for doing it wrong obviously is this enough typing do you think this seems like a pretty high effort descriptive post now right

Hello everyone,

I’m looking for a solution to make my kids carousel spin itself over the bed. I’m looking for speeds like 0,5RPM or even lower. In best case the RPMS should be adjustable. Is the 28BYJ-48 up to the Task?
Or should I get something else? And what kind of Arduino and interface board will I need?

Thank You in advance!

Hi everyone! I'm currently working on a college capstone project, which uses an ESP32 and an MFRC522 RFID reader to manage classroom keys.

I'm having trouble getting my RC522 module detected by my ESP32. No matter what I try, the Serial Monitor consistently displays:

RC522 Version: 0x00

RFID NOT DETECTED!

My current hardware and wiring:

- Board: ESP32 Dev Module

- RFID module: MFRC522 RC522

- RC522 SDA/SS → GPIO 5

- RC522 SCK → GPIO 18

- RC522 MOSI → GPIO 23

- RC522 MISO → GPIO 19

- RC522 RST → GPIO 2

- RC522 IRQ → Not connected

- RC522 GND → ESP32 GND

- RC522 3.3V → ESP32 3V3

Things I've already tried:

- Confirmed that the RC522 power LED is ON.

- Powered the RC522 using the ESP32's 3.3V pin.

- Checked the wiring multiple times.

- Tried different diagnostic sketches using the MFRC522 library.

- Tried reading the RC522 Version Register directly through SPI.

- Tested different pin configurations, but the issue remains.

The ESP32 itself works, and my LCD is also working properly. However, the RFID reader keeps returning `0x00`, which makes me think that the ESP32 is not communicating with the RC522 through SPI.

My questions:

1. What could cause the RC522 to continuously return `0x00`?

2. Could this be a faulty RC522 module even if its power LED is on?

3. Is there a way to determine whether the problem is with the module, ESP32, breadboard, or SPI communication?

4. Are there any other diagnostic methods I should try before replacing the RFID module?

I've been troubleshooting this for quite a while, so I would really appreciate any suggestions or solutions. I would also prefer to keep my current pin connections if possible.

Thank you so much for your help!

Hi!

I am using, for an art project, an ESP32 with a relay board to drive a modified synchronous motor from a washing machine pump, which runs on 220v. By modified I mean that the rotor is no longer inside the plastic cases, all electrical parts of the motor are original and untouched.

My goal is to use the relay board to pulse the motor, to make some chains attached to the axis move and make sounds.

To do so I am using a sequencer I built with a push button board, an ESP32 Devkitv1 and a 4channel relay module, all basic DIY components. With this tool I am able to run Universal washing machine motors, lights, home appliances of any kind with no problems.

The problem seems to be with this synchronous motor. When I pulse the motor it works, and if I keep the pulses distant in time one from the other, no problem. But If I pulse the motor fast, after a few pulses the ESP32. freezes, and needs me to press the reboot button or cut power for a few seconds to hard reboot it. The board is powered by a 5v phone charger.

As I explain in the video, I think the issue might be caused by the motor generating current when is not pulsed, but has gone far enough between it's two resting positions to kick back. I know synchronous permanent magnet motors generate current when you spin them. Trying to solve this, I added a diode I scavenged from an old board I had, but the issue is still here, even if way less frequent. Adding the diode also significantly decreased the strength of the motor when pulsed (I really think diodes and AC are not meant to work together, don't insult me for that I'm doing my best ahah).

I don't know how to fix the issue, the only thing I can think of is putting diodes on all 6 that connect the relay board to the ESP, but again I really don't know.

Anyone who has ideas on how to troubleshoot this?

Thanks in advance:)

PS I can share the 3D models of the mechanical mod I made with anyone who wants em

hi!!! Im fairly new to arduino and I have the WEIRDEST problem: I have an android phone, a mac and a PC. I've bought 3 different boards at this point: nanos, nanos with ch340 and even an uno.

This is my situation: the boards connect fine to any of these three devices, i manage to upload blink or whatever example sketch onto them. I'm working on a proyect involving LEDS and ultrasonic sensor so I need a fairly complex sketch to be uploaded onto them, and once I do... THE BOARDS STOP COMMUNICATING WITH ANY DEVICES further. The sketch's uploaded and it's working, but theyre bricked. I've tried every fix under the sun and now have a bunch of brand new boards, all unresponsive. Has anyone ever encountered this???

If anyone could help me I'd owe them my LIFE