REV C

REV C

🔧 ADC & Analog Front-End

• Switched back to ADS1115 ADC.
• Removed the ADC VREF circuit and added a solder jumper for VREF selection.
• Standardized all analog scaling to 2.048 V reference (instead of 3.3 V).
• Added voltage dividers for 30 V and 5 V input ranges.
• Set 4–20 mA shunt resistor to 100 Ω.
• Added pull-up resistors on ADS1115 ALERT pin.

⚡ Power & Regulation

• Added a buck converter on the EXT port for 12/24 V → 5 V to power the ESP32.
  • Includes a jumper to enable/disable EXT-port power.
  • EXT port may now be used as power-only, reference-only, or both.
• Added 3.3 V ↔ 5.0 V buffer for WS2818 LED.
• Switched to green LEDs for power indication.
• Removed the USB-to-serial and USB hub for a simplified ESP32-S3 design.

🧩 Connectors & I/O

• Added QWIIC header.
• Moved pluggable terminal blocks down 0.5 mm.
• Removed jumper for EXT power selection.

🧪 Test Points

• Added test points for 3.3 V, 5.0 V, 24 V, GND, SDA, SCL, and others.
• Standardized all test points to 1.5×0.7 mm.

🔊 Piezo & Indicators

• Switched to passive piezo and added diode (Huaneng QMB-09B-03).

🧱 Mechanical & Layout

• Changed upper mounting holes to SMTSO3080CTJ hardware.
• Switched to SMT boot/reset buttons.
• Removed RTC clock crystal.
• Switched boost converter to MT3608B for 24 V generation.

Rev B

Fairly large update to the board. Changes include:

• integrated esp32-s3 onboard, no more modules
• switched to MCP3564 ADC for better resolution
• added ability to include an external voltage reference
• added piezo buzzer
• added clean adc regulator and voltage reference
• removed 1k pullup and changed to passthru

Rev A

First revision of the board sent to production.