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 format, will be converted to new template when applied)
{"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.