Troubleshooting

I2C is popular because many sensors, displays, real-time clocks, ADCs, DACs and I/O expanders can share the same two signal wires: SDA and SCL. This makes wiring much cleaner than using a separate set of pins for every module. But I2C has one important rule: each device on the same bus must have its own […]

I2C is one of the most useful communication interfaces for Arduino, ESP32, ESP8266, RP2040, Raspberry Pi Pico and CANABLOX projects. It allows many sensors, displays, real-time clocks, ADCs, DACs and I/O expanders to share only two signal wires: SDA and SCL. But I2C has one important electrical detail that causes many real-world problems: the bus

One of the most common ESP32 problems is an upload error that says something like “Timed out waiting for packet header”, “Failed to connect to ESP32”, or “No serial data received.” This can be very frustrating because the board may appear to be connected correctly, the USB port may show up in the Arduino IDE,

A very common troubleshooting situation is this: an I2C display, sensor, RTC, ADC or I/O expander works perfectly with an Arduino Uno, but the same module does not work with an ESP32. The I2C scanner may find nothing, the display may stay blank, or the sensor library may report that the device is missing. This

An I2C scanner is one of the most useful troubleshooting tools for Arduino, ESP32, ESP8266, RP2040 and similar microcontroller projects. It sends test messages to all possible I2C addresses and reports which devices answer. When everything is wired correctly, an I2C scanner usually prints one or more addresses such as 0x3C, 0x27, 0x68 or 0x48.

Analog sensors are often used with Arduino, ESP32, ESP8266, RP2040 and other microcontroller boards to measure light, temperature, voltage, position, pressure, moisture or sound level. The idea seems simple: connect the sensor output to an analog input and read a number. In real projects, analog readings are often more confusing. The value may jump around,

Finding an I2C address with a scanner feels like a big success. It proves that the microcontroller can see something on the bus. But it does not always mean the project will work immediately. A very common situation is this: the I2C scanner finds an address such as 0x3C, 0x27, 0x68 or 0x48, but the

Many users move from Arduino Uno or Nano to ESP32 and expect analogRead() to behave the same way. The code looks familiar, the function name is the same, and the ESP32 has many analog-capable pins. But the results can be surprising. ESP32 analog readings may be noisy, nonlinear, unstable, or different from what a multimeter

Small OLED displays are very popular in Arduino, ESP32, ESP8266, RP2040 and CANABLOX projects. They are bright, compact, inexpensive and easy to connect with only a few wires. But they can also be surprisingly frustrating. A display may be detected by an I2C scanner, but still show nothing, random pixels, shifted text, broken graphics or

SPI displays are widely used in Arduino, ESP32, ESP8266, RP2040 and embedded projects. They include small OLED displays, TFT displays, ST7567 graphic LCDs, ST7920 graphic LCDs, ILI9341 TFTs, ST7735 / ST7789 displays and many other modules. Compared with I2C displays, SPI displays can be faster and more flexible. But they also need more wires, more