IoT Hardware Checklist

IoT Hardware Checklist

The most common IoT project delay is not a technical problem — it is discovering you are missing a component or connector three hours into a build. This checklist covers every hardware category to verify before ordering and before building.

Phase 1: Requirements (Before Ordering)

Power Requirements

• What is the supply voltage? (3.3V, 5V, 12V, mains?)
• What is the peak current draw? (Add all active components + 20% margin)
• Is the power source AC or DC? Battery, USB, or mains-derived?
• Battery-powered: what is the target runtime? → determines battery capacity
• Mains-powered: have you selected the right HLK-PM module or SMPS?

Connectivity

• WiFi required? → ESP32 or NodeMCU
• Bluetooth / BLE required? → ESP32 only
• GSM/cellular required? → SIM800L or SIM7600 module
• GPS required? → NEO-6M module
• Offline operation required? → SD card module + RTC (DS3231)

Sensor Protocols

• List every sensor and its protocol (I2C, SPI, UART, analog, digital)
• Do any sensors need 5V that the ESP32 cannot provide directly? → level shifter required
• How many ADC channels needed? Ensure they are ADC1 pins on ESP32 if WiFi is used
• Are I2C addresses unique? If two sensors share an address → need I2C multiplexer (TCA9548A)

Phase 2: Component List Verification

Core Electronics

• Microcontroller board confirmed and in cart
• All sensors confirmed (check voltage compatibility with MCU)
• Actuators confirmed (relay, motor driver, servo)
• Display confirmed if needed (OLED, LCD)
• Communication modules confirmed (RFID, GSM, GPS)

Passive Components

• Pull-up resistors for I2C lines (4.7 kΩ) and digital sensors (10 kΩ)
• Current-limiting resistors for LEDs (220–330 Ω)
• Decoupling capacitors (100 nF ceramic, 100 µF electrolytic)
• Transistors for buzzer/relay drivers (BC547 or 2N2222)

Connectors and Wiring

• Jumper wire set (M-M, M-F, F-F) available
• Terminal blocks for power connections
• USB cable for programming
• Appropriate fuse for mains-connected loads

Enclosure

• Enclosure selected with correct IP rating for the environment
• Cable glands for wire entry points
• Mounting hardware (M3 standoffs for PCB, M3 screws)

Phase 3: Pre-Build Verification

• Read the datasheet for every new component — note VCC range and logic levels
• Verify all 3.3V sensors before connecting to ESP32 (measure with multimeter first)
• Flash a simple test sketch to the MCU before connecting anything else
• Test each sensor individually before combining into the full circuit
• Verify I2C addresses with an I2C scanner sketch before adding multiple I2C devices

Phase 4: Pre-Deployment

• Power cycle the completed build 10 times — verify consistent boot
• Simulate WiFi outage — verify reconnect behavior
• Run for 24 hours — check for memory leaks, watchdog resets, sensor drift
• Test at temperature extremes if outdoor deployment
• Verify OTA update mechanism works before sealing in enclosure

Stock all common components in advance — browse Circuitkar's catalog and order resistors, capacitors, and connectors in bulk so you always have them on hand.