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An MCP3008 code is a ratio to VREF, not an absolute voltage. Use 1024 code intervals, preserve the reference value and do not mistake the top code for VREF itself.
MCP3008 ADC Codes: Convert Readings With the Voltage You Actually Reference Read More
A PCA9685 stores pulse edges as 12-bit counts, not microseconds. Convert the servo pulse width using the actual PWM frequency, then calibrate the oscillator before trimming endpoints.
PCA9685 Servo Timing: Convert Microseconds to 12-Bit Counts Without Guessing Read More
An ADS1115 repeatedly returning 0x7FFF has reached positive full scale. Check the PGA range and absolute input limits before treating extra samples as more precision.
ADS1115 Full-Scale Codes: Why 0x7FFF Usually Means Clipping Read More
An ESP32 that wakes as soon as it sleeps may still see an active EXT0 or EXT1 level. Print the wake cause, inspect the pin state, and deinitialize RTC GPIO after EXT0 wake.
ESP32 Wakes Immediately From Deep Sleep? Read the Wake Cause Before Changing Pins Read More
A MAX31855 NaN is a fault flag, not a diagnosis. Read the low three bits to separate an open thermocouple from shorts to ground or supply.
MAX31855 Reads NaN? Decode the Fault Bits Before Rewiring the Thermocouple Read More
A counterfeit card can report a large volume while storing only a fraction of it. F3 writes and reads the claimed space so aliasing, corruption and overwritten sectors become visible.
Verify a microSD Card’s Real Capacity with F3 Before Trusting It Read More
A 4–20 mA loop can read zero because the supply is missing, the series path is open or the meter is connected incorrectly. These measurements separate the three without hiding the fault.
Reading 0 mA on a 4–20 mA Loop? Find the Open Without Bypassing the Fault Read More
A bench oscilloscope’s probe ground is usually bonded to protective earth. Connecting it to a live or floating node can create a low-impedance short; use an appropriately rated differential method instead.
Your Oscilloscope Ground Clip Is Earth: Avoid the Accidental Short Read More
RSSI measures received power; SNR measures separation from the noise floor. Log both by location and spreading factor before moving a LoRaWAN gateway or replacing an antenna.
LoRaWAN RSSI and SNR: Move the Gateway With Evidence, Not Guesswork Read More
A stuck-low I²C bus is usually a state or electrical problem, not a missing address. Use SCL/SDA measurements, a nine-clock recovery and staged isolation to find the failing device.
I²C Bus Stuck Low? Diagnose SDA Before Power-Cycling Everything Read More