DIY ESP-01 and PZEM-004T Energy Meter
DIY ESP-01 and PZEM-004T

Available from:

GPIO #Component
GPIO00 None
GPIO02 None
GPIO04 None
GPIO05 None
GPIO09 None
GPIO10 None
GPIO12 None
GPIO13 None
GPIO14 None
GPIO15 None
GPIO16 None
Configuration (old version)
{"NAME":"HW-655 PZEM","GPIO":[0,63,0,62,0,0,0,0,0,0,0,0,0],"FLAG":0,"BASE":18}

The PZEM-004T together with a HW-655 Relay provide a good clamp-on energy monitor for a 240V clothes dryer.

Parts needed


Install Tasmota (tasmota.bin) is sufficient) on the ESP-01 and confirm it is functional before connecting the PZEM-004T to its serial interface. Use of pins other that the default hardware serial GPIO (01 & 03) in order for Tasmota to emulate a serial interface using software serial.

Hardware connections

Connect the serial interface of the HW-655 with the serial interface of the PZEM-004T.

As most parts are connected to high voltage AC it is recommended to fit the hardware in a solid enclosure.

Software configuration

Device Template
PZEM-004T version prior to V3:

{"NAME":"HW-655 PZEM","GPIO":[0,63,0,62,0,0,0,0,0,0,0,0,0],"FLAG":0,"BASE":18}

PZEM-004T version V3:

{"NAME":"HW-655 PZEM","GPIO":[0,98,0,62,0,0,0,0,0,0,0,0,0],"FLAG":0,"BASE":18}

Use the module template to configure the GPIO’s for hardware serial connection.

IMPORTANT: If using the connections as following, the communication works in all cores due to TASMOTA using hardware serial. If the user wants to use other GPIOs for communication, TASMOTA will emulate a serial interface using software serial. This feature does not work using core 2.3.0 due to insufficient RAM. To use the software serial feature, you must use a core version of 2.4.2 or greater.


Per Theo - As the PZEM is a dedicated energy monitor, device calibration in TASMOTA is currently not supported.