The main chip using ESP32, Tensilica LX6 dual-core processor, clocked at 240MHz, computing power up to 600DMIPS, chip built-in 520 KB SRAM, 802.11 b / g / N HT40 Wi-Fi transceiver, baseband, protocol stack and LWIP, integrated dual-mode Bluetooth (traditional Bluetooth and BLE low power Bluetooth).

This product is based on the WIFI 32 added SX1278 chip, that is, LoRa ™ remote modem, 433MHz frequency, about -148dBm high sensitivity, +20 dBm power output, high reliability.

Onboard 32MBit Flash, Wi-Fi antenna, lithium battery charging circuit and interface, CP2102 USB to serial chip, the perfect support for Arduino development environment, can be very simple and fast for program verification and product development.

Specification

• Operating voltage: 3.3V to 7V
• Operating temperature range: -40 ° C to + 90 ° C
• Supports Sniffer, Station, softAP and Wi-Fi Direct modes
• Data rate: 150 Mbps @ 11n HT40,72 Mbps @ 11n HT20,54 Mbps @ 11g, 11 Mbps @ 11b
• Transmit power: 19.5 dBm @ 11b, 16.5 dBm @ 11g, 15.5 dBm @ 11n
• Receiver sensitivity up to - 98 dBm
• UDP continues to throughput by 135 Mbps

SampleReceiver.py

from machine import Pin, SPI
from Lib.sx127x import SX127x
 
# Board specific Lora configuration
lora_default = {
    'frequency': 433e6,
    'frequency_offset':0,
    'tx_power_level': 14,
    'signal_bandwidth': 125e3,
    'spreading_factor': 9,
    'coding_rate': 5,
    'preamble_length': 8,
    'implicitHeader': False,
    'sync_word': 0x12,
    'enable_CRC': True,
    'invert_IQ': False,
    'debug': False,
}
 
lora_pins = {
    'dio_0':26,
    'ss':18,
    'reset':16,
    'sck':5,
    'miso':19,
    'mosi':27,
}
 
lora_spi = SPI(
    baudrate=10000000, polarity=0, phase=0,
    bits=8, firstbit=SPI.MSB,
    sck=Pin(lora_pins['sck'], Pin.OUT, Pin.PULL_DOWN),
    mosi=Pin(lora_pins['mosi'], Pin.OUT, Pin.PULL_UP),
    miso=Pin(lora_pins['miso'], Pin.IN, Pin.PULL_UP),
)
 
lora = SX127x(lora_spi, pins=lora_pins, parameters=lora_default)
print("LoRa Started");
 
while True:
	if lora.receivedPacket():
		try:
			payload = lora.readPayload().decode()
			rssi = lora.packetRssi()
			snr = lora.packetSnr()
			print("RX: {} | RSSI: {} SNR: {}".format(payload, rssi, snr))

SampleTransmitter.py

from machine import Pin, SPI
from Lib.sx127x import SX127x
 
# Board specific Lora configuration
lora_default = {
    'frequency': 433e6,
    'frequency_offset':0,
    'tx_power_level': 14,
    'signal_bandwidth': 125e3,
    'spreading_factor': 9,
    'coding_rate': 5,
    'preamble_length': 8,
    'implicitHeader': False,
    'sync_word': 0x12,
    'enable_CRC': True,
    'invert_IQ': False,
    'debug': False,
}
 
lora_pins = {
    'dio_0':26,
    'ss':18,
    'reset':16,
    'sck':5,
    'miso':19,
    'mosi':27,
}
 
lora_spi = SPI(
    baudrate=10000000, polarity=0, phase=0,
    bits=8, firstbit=SPI.MSB,
    sck=Pin(lora_pins['sck'], Pin.OUT, Pin.PULL_DOWN),
    mosi=Pin(lora_pins['mosi'], Pin.OUT, Pin.PULL_UP),
    miso=Pin(lora_pins['miso'], Pin.IN, Pin.PULL_UP),
)
 
lora = SX127x(lora_spi, pins=lora_pins, parameters=lora_default)
print("LoRa Started");
 
lora.println("Sending first lora message")

SX127x.py

from time import sleep, ticks_ms
from machine import SPI, Pin
from micropython import const
import gc
 
 
PA_OUTPUT_RFO_PIN = const(0)
PA_OUTPUT_PA_BOOST_PIN = const(1)
 
# registers
REG_FIFO = const(0x00)
REG_OP_MODE = const(0x01)
REG_FRF_MSB = const(0x06)
REG_FRF_MID = const(0x07)
REG_FRF_LSB = const(0x08)
REG_PA_CONFIG = const(0x09)
REG_LNA = const(0x0C)
REG_FIFO_ADDR_PTR = const(0x0D)
 
REG_FIFO_TX_BASE_ADDR = const(0x0E)
FifoTxBaseAddr = const(0x00)
 
REG_FIFO_RX_BASE_ADDR = const(0x0F)
FifoRxBaseAddr = const(0x00)
REG_FIFO_RX_CURRENT_ADDR = const(0x10)
REG_IRQ_FLAGS_MASK = const(0x11)
REG_IRQ_FLAGS = const(0x12)
REG_RX_NB_BYTES = const(0x13)
REG_PKT_RSSI_VALUE = const(0x1A)
REG_PKT_SNR_VALUE = const(0x19)
REG_MODEM_CONFIG_1 = const(0x1D)
REG_MODEM_CONFIG_2 = const(0x1E)
REG_PREAMBLE_MSB = const(0x20)
REG_PREAMBLE_LSB = const(0x21)
REG_PAYLOAD_LENGTH = const(0x22)
REG_FIFO_RX_BYTE_ADDR = const(0x25)
REG_MODEM_CONFIG_3 = const(0x26)
REG_RSSI_WIDEBAND = const(0x2C)
REG_DETECTION_OPTIMIZE = const(0x31)
REG_DETECTION_THRESHOLD = const(0x37)
REG_SYNC_WORD = const(0x39)
REG_DIO_MAPPING_1 = const(0x40)
REG_VERSION = const(0x42)
 
# invert IQ
REG_INVERTIQ = const(0x33)
RFLR_INVERTIQ_RX_MASK = const(0xBF)
RFLR_INVERTIQ_RX_OFF = const(0x00)
RFLR_INVERTIQ_RX_ON = const(0x40)
RFLR_INVERTIQ_TX_MASK = const(0xFE)
RFLR_INVERTIQ_TX_OFF = const(0x01)
RFLR_INVERTIQ_TX_ON = const(0x00)
 
REG_INVERTIQ2 = const(0x3B)
RFLR_INVERTIQ2_ON = const(0x19)
RFLR_INVERTIQ2_OFF = const(0x1D)
 
# modes
# bit 7: 1 => LoRa mode
MODE_LONG_RANGE_MODE = const(0x80)
MODE_SLEEP = const(0x00)
MODE_STDBY = const(0x01)
MODE_TX = const(0x03)
MODE_RX_CONTINUOUS = const(0x05)
MODE_RX_SINGLE = const(0x06)
 
# PA config
PA_BOOST = const(0x80)
 
# IRQ masks
IRQ_TX_DONE_MASK = const(0x08)
IRQ_PAYLOAD_CRC_ERROR_MASK = const(0x20)
IRQ_RX_DONE_MASK = const(0x40)
IRQ_RX_TIME_OUT_MASK = const(0x80)
 
# Buffer size
MAX_PKT_LENGTH = const(255)
 
 
class SX127x:
 
    default_parameters = {
        "frequency": 869525000,
        "frequency_offset": 0,
        "tx_power_level": 14,
        "signal_bandwidth": 125e3,
        "spreading_factor": 9,
        "coding_rate": 5,
        "preamble_length": 8,
        "implicitHeader": False,
        "sync_word": 0x12,
        "enable_CRC": True,
        "invert_IQ": False,
    }
 
    def __init__(self, spi, pins, parameters={}):
        self.spi = spi
        self.pins = pins
        self.parameters = parameters
 
        self.pin_ss = Pin(self.pins["ss"], Pin.OUT)
 
        self.lock = False
        self.implicit_header_mode = None
 
        self.parameters = SX127x.default_parameters
        if parameters:
            self.parameters.update(parameters)
 
        # check version
        version = None
        for i in range(5):
            version = self.readRegister(REG_VERSION)
            if version:
                break
        # debug output
        print("SX version: {}".format(version))
 
        # put in LoRa and sleep mode
        self.sleep()
        # config
        self.setFrequency(self.parameters["frequency"])
        self.setSignalBandwidth(self.parameters["signal_bandwidth"])
 
        # set LNA boost
        self.writeRegister(REG_LNA, self.readRegister(REG_LNA) | 0x03)
        # set auto AGC
        self.writeRegister(REG_MODEM_CONFIG_3, 0x04)
 
        self.setTxPower(self.parameters["tx_power_level"])
        self.implicitHeaderMode(self.parameters["implicitHeader"])
        self.setSpreadingFactor(self.parameters["spreading_factor"])
        self.setCodingRate(self.parameters["coding_rate"])
        self.setPreambleLength(self.parameters["preamble_length"])
        self.setSyncWord(self.parameters["sync_word"])
        self.enableCRC(self.parameters["enable_CRC"])
        self.invertIQ(self.parameters["invert_IQ"])
 
        # set LowDataRateOptimize flag if symbol time > 16ms (default disable on reset)
        # self.writeRegister(REG_MODEM_CONFIG_3, self.readRegister(REG_MODEM_CONFIG_3) & 0xF7)  # default disable on reset
        bw = self.parameters["signal_bandwidth"]
        sf = self.parameters["spreading_factor"]
        if 1000 / bw / 2 ** sf > 16:
            self.writeRegister(
                REG_MODEM_CONFIG_3, self.readRegister(REG_MODEM_CONFIG_3) | 0x08
            )
 
        # set base addresses
        self.writeRegister(REG_FIFO_TX_BASE_ADDR, FifoTxBaseAddr)
        self.writeRegister(REG_FIFO_RX_BASE_ADDR, FifoRxBaseAddr)
 
        self.standby()
 
    def beginPacket(self, implicitHeaderMode=False):
        self.standby()
        self.implicitHeaderMode(implicitHeaderMode)
 
        # reset FIFO address and payload length
        self.writeRegister(REG_FIFO_ADDR_PTR, FifoTxBaseAddr)
        self.writeRegister(REG_PAYLOAD_LENGTH, 0)
 
    def endPacket(self):
        # put in TX mode
        self.writeRegister(REG_OP_MODE, MODE_LONG_RANGE_MODE | MODE_TX)
        # wait for TX done, standby automatically on TX_DONE
        while (self.readRegister(REG_IRQ_FLAGS) & IRQ_TX_DONE_MASK) == 0:
            pass
        # clear IRQ's
        self.writeRegister(REG_IRQ_FLAGS, IRQ_TX_DONE_MASK)
 
    def write(self, buffer):
        currentLength = self.readRegister(REG_PAYLOAD_LENGTH)
        size = len(buffer)
 
        # check size
        size = min(size, (MAX_PKT_LENGTH - FifoTxBaseAddr - currentLength))
 
        # write data
        for i in range(size):
            self.writeRegister(REG_FIFO, buffer[i])
 
        # update length
        self.writeRegister(REG_PAYLOAD_LENGTH, currentLength + size)
        return size
 
    def aquirelock(self, lock=False):
#         self.lock = False
        self.lock = lock
 
    def println(self, message, implicitHeader=False, repeat=1):
        # wait until RX_Done, lock and begin writing
        self.aquirelock(True)
 
        if isinstance(message, str):
            message = message.encode()
 
        self.beginPacket(implicitHeader)
        self.write(message)
 
        for i in range(repeat):
            self.endPacket()
 
        # unlock when done writing
        self.aquirelock(False)
        self.collectGarbage()
 
    def getIrqFlags(self):
        irqFlags = self.readRegister(REG_IRQ_FLAGS)
        self.writeRegister(REG_IRQ_FLAGS, irqFlags)
        return irqFlags
 
    def packetRssi(self, rfi="hf"):
        packet_rssi = self.readRegister(REG_PKT_RSSI_VALUE)
        return packet_rssi - (157 if rfi == "hf" else 164)
 
    def packetSnr(self):
        return (self.readRegister(REG_PKT_SNR_VALUE)) * 0.25
 
    def standby(self):
        self.writeRegister(REG_OP_MODE, MODE_LONG_RANGE_MODE | MODE_STDBY)
 
    def sleep(self):
        self.writeRegister(REG_OP_MODE, MODE_LONG_RANGE_MODE | MODE_SLEEP)
 
    def setTxPower(self, level, outputPin=PA_OUTPUT_PA_BOOST_PIN):
        self.parameters["tx_power_level"] = level
        if outputPin == PA_OUTPUT_RFO_PIN:
            # RFO
            level = min(max(level, 0), 14)
            self.writeRegister(REG_PA_CONFIG, 0x70 | level)
        else:
            # PA BOOST
            level = min(max(level, 2), 17)
            self.writeRegister(REG_PA_CONFIG, PA_BOOST | (level - 2))
 
    def setFrequency(self, frequency):
        # TODO min max limit
        frequency = int(frequency)
        self.parameters["frequency"] = frequency
        frequency += self.parameters["frequency_offset"]
 
        frf = (frequency << 19) // 32000000
        self.writeRegister(REG_FRF_MSB, (frf >> 16) & 0xFF)
        self.writeRegister(REG_FRF_MID, (frf >> 8) & 0xFF)
        self.writeRegister(REG_FRF_LSB, (frf >> 0) & 0xFF)
 
    def setSpreadingFactor(self, sf):
        sf = min(max(sf, 6), 12)
        self.writeRegister(REG_DETECTION_OPTIMIZE, 0xC5 if sf == 6 else 0xC3)
        self.writeRegister(REG_DETECTION_THRESHOLD, 0x0C if sf == 6 else 0x0A)
        self.writeRegister(
            REG_MODEM_CONFIG_2,
            (self.readRegister(REG_MODEM_CONFIG_2) & 0x0F) | ((sf << 4) & 0xF0),
        )
 
    def setSignalBandwidth(self, sbw):
        bins = (
            7.8e3,
            10.4e3,
            15.6e3,
            20.8e3,
            31.25e3,
            41.7e3,
            62.5e3,
            125e3,
            250e3,
        )
        bw = 9
 
        if sbw < 10:
            bw = sbw
        else:
            for i in range(len(bins)):
                if sbw <= bins[i]:
                    bw = i
                    break
 
        self.writeRegister(
            REG_MODEM_CONFIG_1,
            (self.readRegister(REG_MODEM_CONFIG_1) & 0x0F) | (bw << 4),
        )
 
    def setCodingRate(self, denominator):
        denominator = min(max(denominator, 5), 8)
        cr = denominator - 4
        self.writeRegister(
            REG_MODEM_CONFIG_1,
            (self.readRegister(REG_MODEM_CONFIG_1) & 0xF1) | (cr << 1),
        )
 
    def setPreambleLength(self, length):
        self.writeRegister(REG_PREAMBLE_MSB, (length >> 8) & 0xFF)
        self.writeRegister(REG_PREAMBLE_LSB, (length >> 0) & 0xFF)
 
    def enableCRC(self, enable_CRC=False):
        modem_config_2 = self.readRegister(REG_MODEM_CONFIG_2)
        config = modem_config_2 | 0x04 if enable_CRC else modem_config_2 & 0xFB
        self.writeRegister(REG_MODEM_CONFIG_2, config)
 
    def invertIQ(self, invertIQ):
        self.parameters["invertIQ"] = invertIQ
        if invertIQ:
            self.writeRegister(
                REG_INVERTIQ,
                (
                    (
                        self.readRegister(REG_INVERTIQ)
                        & RFLR_INVERTIQ_TX_MASK
                        & RFLR_INVERTIQ_RX_MASK
                    )
                    | RFLR_INVERTIQ_RX_ON
                    | RFLR_INVERTIQ_TX_ON
                ),
            )
            self.writeRegister(REG_INVERTIQ2, RFLR_INVERTIQ2_ON)
        else:
            self.writeRegister(
                REG_INVERTIQ,
                (
                    (
                        self.readRegister(REG_INVERTIQ)
                        & RFLR_INVERTIQ_TX_MASK
                        & RFLR_INVERTIQ_RX_MASK
                    )
                    | RFLR_INVERTIQ_RX_OFF
                    | RFLR_INVERTIQ_TX_OFF
                ),
            )
            self.writeRegister(REG_INVERTIQ2, RFLR_INVERTIQ2_OFF)
 
    def setSyncWord(self, sw):
        self.writeRegister(REG_SYNC_WORD, sw)
 
    def setChannel(self, parameters):
        self.standby()
        for key in parameters:
            if key == "frequency":
                self.setFrequency(parameters[key])
                continue
            if key == "invert_IQ":
                self.invertIQ(parameters[key])
                continue
            if key == "tx_power_level":
                self.setTxPower(parameters[key])
                continue
 
    def dumpRegisters(self):
        # TODO end=''
        for i in range(128):
            print("0x{:02X}: {:02X}".format(i, self.readRegister(i)), end="")
            if (i + 1) % 4 == 0:
                print()
            else:
                print(" | ", end="")
 
    def implicitHeaderMode(self, implicitHeaderMode=False):
        if (
            self.implicit_header_mode != implicitHeaderMode
        ):  # set value only if different.
            self.implicit_header_mode = implicitHeaderMode
            modem_config_1 = self.readRegister(REG_MODEM_CONFIG_1)
            config = (
                modem_config_1 | 0x01
                if implicitHeaderMode
                else modem_config_1 & 0xFE
            )
            self.writeRegister(REG_MODEM_CONFIG_1, config)
 
    def receive(self, size=0):
        self.implicitHeaderMode(size > 0)
        if size > 0:
            self.writeRegister(REG_PAYLOAD_LENGTH, size & 0xFF)
 
        # The last packet always starts at FIFO_RX_CURRENT_ADDR
        # no need to reset FIFO_ADDR_PTR
        self.writeRegister(
            REG_OP_MODE, MODE_LONG_RANGE_MODE | MODE_RX_CONTINUOUS
        )
 
    def listen(self, time=1000):
        time = min(max(time, 0), 10000)
        self.receive()
 
        start = ticks_ms()
        while True:
            if self.receivedPacket():
                return self.readPayload()
            if ticks_ms() - start > time:
                return None
 
    def onReceive(self, callback):
        self.onReceive = callback
 
        if "dio_0" in self.pins:
            self.pin_rx_done = Pin(self.pins["dio_0"], Pin.IN)
 
        if self.pin_rx_done:
            if callback:
                self.writeRegister(REG_DIO_MAPPING_1, 0x00)
                self.pin_rx_done.irq(
                    trigger=Pin.IRQ_RISING, handler=self.handleOnReceive
                )
            else:
                pass
                # TODO detach irq
 
    def handleOnReceive(self, event_source):
        # lock until TX_Done
        self.aquirelock(True)
        irqFlags = self.getIrqFlags()
        # RX_DONE only, irqFlags should be 0x40
        if irqFlags & IRQ_RX_DONE_MASK == IRQ_RX_DONE_MASK:
            # automatically standby when RX_DONE
            if self.onReceive:
                payload = self.readPayload()
                self.onReceive(self, payload)
 
        elif self.readRegister(REG_OP_MODE) != (
            MODE_LONG_RANGE_MODE | MODE_RX_SINGLE
        ):
            # no packet received.
            # reset FIFO address / # enter single RX mode
            self.writeRegister(REG_FIFO_ADDR_PTR, FifoRxBaseAddr)
            self.writeRegister(
                REG_OP_MODE, MODE_LONG_RANGE_MODE | MODE_RX_SINGLE
            )
 
        self.aquirelock(False)  # unlock in any case.
        self.collectGarbage()
        return True
 
    def receivedPacket(self, size=0):
        irqFlags = self.getIrqFlags()
        self.implicitHeaderMode(size > 0)
        if size > 0:
            self.writeRegister(REG_PAYLOAD_LENGTH, size & 0xFF)
 
        # if (irqFlags & IRQ_RX_DONE_MASK) and \
        # (irqFlags & IRQ_RX_TIME_OUT_MASK == 0) and \
        # (irqFlags & IRQ_PAYLOAD_CRC_ERROR_MASK == 0):
 
        if (
            irqFlags == IRQ_RX_DONE_MASK
        ):  # RX_DONE only, irqFlags should be 0x40
            # automatically standby when RX_DONE
            return True
 
        elif self.readRegister(REG_OP_MODE) != (
            MODE_LONG_RANGE_MODE | MODE_RX_SINGLE
        ):
            # no packet received.
            # reset FIFO address / # enter single RX mode
            self.writeRegister(REG_FIFO_ADDR_PTR, FifoRxBaseAddr)
            self.writeRegister(
                REG_OP_MODE, MODE_LONG_RANGE_MODE | MODE_RX_SINGLE
            )
 
    def readPayload(self):
        # set FIFO address to current RX address
        # fifo_rx_current_addr = self.readRegister(REG_FIFO_RX_CURRENT_ADDR)
        self.writeRegister(
            REG_FIFO_ADDR_PTR, self.readRegister(REG_FIFO_RX_CURRENT_ADDR)
        )
 
        # read packet length
        packet_length = 0
        if self.implicit_header_mode:
            packet_length = self.readRegister(REG_PAYLOAD_LENGTH)
        else:
            packet_length = self.readRegister(REG_RX_NB_BYTES)
 
        payload = bytearray()
        for i in range(packet_length):
            payload.append(self.readRegister(REG_FIFO))
 
        self.collectGarbage()
        return bytes(payload)
 
    def readRegister(self, address, byteorder="big", signed=False):
        response = self.transfer(address & 0x7F)
        return int.from_bytes(response, byteorder)
 
    def writeRegister(self, address, value):
        self.transfer(address | 0x80, value)
 
    def transfer(self, address, value=0x00):
        response = bytearray(1)
 
        self.pin_ss.value(0)
 
        self.spi.write(bytes([address]))
        self.spi.write_readinto(bytes([value]), response)
 
        self.pin_ss.value(1)
 
        return response
 
    def collectGarbage(self):
        gc.collect()
        # print('[Mem aft - free: {}   allocated: {}]'.format(gc.mem_free(), gc.mem_alloc()))