WIRING GUIDE

ESP32 IoT Energy Monitor — ETEC 495 — Dustin Bloss

⚡ Wire components 1–4 first with USB power only. The Hi-Link (Step 5) connects to AC mains — do that LAST after everything else works.
🖥️ STEP 1 — LCD 20x4 DISPLAY SAFE · DO FIRST
LCD
GND		 → ESP32 GND
LCD
VCC		 → ESP32 5V
LCD
SDA		 → ESP32 P21
LCD
SCL		 → ESP32 P22
🕐 STEP 2 — RTC HW-111 (DS1307) SAFE
RTC HW-111
GND		 → ESP32 GND
RTC HW-111
VCC		 → ESP32 3V3
RTC HW-111
SDA		 → ESP32 P21
⚠️ Same row on breadboard as LCD SDA
RTC HW-111
SCL		 → ESP32 P22
⚠️ Same row on breadboard as LCD SCL
💡 Don't forget: insert a CR2032 coin battery into the RTC's battery slot so it keeps time when unplugged.
💾 STEP 3 — SD CARD HW-125 SAFE
SD Card
GND		 → ESP32 GND
SD Card
VCC		 → ESP32 3V3
SD Card
CS		 → ESP32 P5
SD Card
SCK		 → ESP32 P18
SD Card
MOSI		 → ESP32 P23
SD Card
MISO		 → ESP32 P19
⚡ STEP 4 — PZEM-004T (GREEN BOARD) SAFE — LOW VOLTAGE SIDE
PZEM-004T
GND		 → ESP32 GND
PZEM-004T
5V / VCC		 → ESP32 5V
PZEM-004T
TX		 → ESP32 P16
PZEM talks → ESP32 listens (RX2)
PZEM-004T
RX		 → ESP32 P17
ESP32 talks → PZEM listens (TX2)
🔌 CT CLAMP: The red and black wires from the CT clamp screw into the green terminal block at the bottom of the PZEM board. Either wire in either terminal — polarity doesn't matter for the CT clamp.
🔴 STEP 5 — HI-LINK HLK-2M05 (AC MAINS) DO THIS LAST
⚠️ THIS IS 120V AC. TAPE ALL EXPOSED WIRES. DO NOT TOUCH WHEN PLUGGED IN.
Hi-Link
AC (left pin)		 → AC MAINS LIVE (black wire)
Hi-Link
AC (right pin)		 → AC MAINS NEUTRAL (white wire)
Hi-Link
+Vo		 → Buck Converter IN+
Hi-Link
-Vo		 → Buck Converter IN− / GND
Buck Converter
OUT+		 → ESP32 5V (main power)
Set buck to 5.0V with multimeter before connecting
Buck Converter
OUT−		 → ESP32 GND
✅ The CT clamp goes around ONE wire of your AC load (lamp cord, extension cord, etc.) — do not clamp around both wires together.