PZEM-004T v3.0 energy meter (10 A)

from machine import UART
import struct, time

# PZEM RX to TX2 (GPIO17), PZEM TX to RX2 (GPIO16), 5V to VIN, GND to GND
# timeout_char longer than the 26 ms of the 25-byte answer at 9600 baud
uart = UART(2, 9600, tx=17, rx=16, timeout=200, timeout_char=50)

def crc16(dados):
    crc = 0xFFFF
    for b in dados:
        crc ^= b
        for _ in range(8):
            crc = (crc >> 1) ^ 0xA001 if crc & 1 else crc >> 1
    return crc

def ler_medidas(endereco=0x01):
    pedido = bytes([endereco, 0x04, 0, 0, 0, 10])  # 10 registers starting at 0x0000
    c = crc16(pedido)
    uart.write(pedido + bytes([c & 0xFF, c >> 8]))  # CRC: low byte first
    r = uart.read(25)
    if r is None or len(r) != 25 or crc16(r[:-2]) != r[-2] | r[-1] << 8:
        return None  # no answer or wrong CRC: drop it
    v = struct.unpack('>10H', r[3:23])
    return {'V': v[0] / 10, 'A': (v[1] | v[2] << 16) / 1000, 'W': (v[3] | v[4] << 16) / 10,
            'Wh': v[5] | v[6] << 16, 'Hz': v[7] / 10, 'FP': v[8] / 100}

while True:
    print(ler_medidas())
    time.sleep(2)