3. Wire and validate¶
Build the circuit on a breadboard, one step at a time. Each page ends with a checkpoint. Pass it before moving on, so a bad wire shows up early instead of after you flash.
3V3 only, and unplug while you wire
Power the VEML7700 and the display from 3V3. 5V on the logic pins can kill the modules. Unplug USB while you seat jumpers.
The routine¶
Steps 2 to 5 all follow the same loop:
flowchart LR
A[Unplug USB] --> B[Seat the jumpers] --> C[Plug USB] --> D["Check: cool,<br/>about 3.3 V"] --> E[Checkpoint passed]If anything is warm or the meter reads wrong, unplug and go back to the wires before you continue.
Parts¶
| Part | Notes | |
|---|---|---|
| ESP32-C3 DevKit | USB serial for flash and logs | |
| VEML7700 breakout | Ambient light over I2C at 0x10 |
|
| LED (+ series resistor if discrete) | Driven from GPIO6, on/off only | |
| ST7789 240×240 SPI display | Square IPS, 8-pin header (GND to BL) |
|
| Solderless breadboard | 400 or 830 holes, half or full size | |
| DuPont M–M jumpers | Board to rail, board to board | |
| USB data cable | Charge-only cables never show a serial port |
Steps¶
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How the holes are already tied.
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Board on the breadboard, 3V3 and GND on the rails.
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Power, then I2C.
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GPIO6 to the LED.
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Power, then SPI.
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The full pin map and a USB check.
The full pin map is on Validate once everything is wired.