User manual EBYTE E32 series

User manual EBYTE E32-868T20D

E32-868T20D is a wireless serial port module (UART) based on SEMTECH's SX1276 RF chip. It has multiple transmission modes working in the 862MHz~893MHz range (default 868MHz).

• Communication distance tested is up to 3km
• Maximum transmission power of 100mW, software multi-level adjustable;
• Support the global license-free ISM 868MHz band;
• Support air date rate of 0.3kbps~19.2kbps;
• Low power consumption for battery supplied applications;
• Support 2.3V~5.2V power supply;
• Industrial grade standard design, support -40 ~ 85 °C for working over a long time;
• SMA access point, Easy connection of coaxial cable or external antenna

(*) All communication pins are 3.3V only !!!

For the E32-868T20D, the minimum frequency is 862 MHz and the maximum is 893 MHz. The working frequency of the module is set by the channel number. The formula is :

• Module frequency = Minimum frequency + channel_number * 1 MHz The default channel number for the E32-868T20D module is 6, so the working frequency defaults to 862 MHz + 6*1 MHz = 868 MHz

1. Transparent transmission
   All modules have the same address and channel and can send/receive messages to/from each other (demo mode). The messages don't include address and channel information.

2. Fixed transmission
   All modules can have different addresses and channels. The transmission messages are prefixed with the destination address and channel information. If these differ from the settings of the transmitter, then the configuration of the module will be changed before the transmission. After the transmission is complete, the transmitter will revert to its prior configuration.

   • Fixed transmission P2P
     The transmitted message has the address and channel information of the receiver. Only this module will receive the message. This is a point to point transmission between 2 modules.
     

   • Fixed transmission broadcast
     The transmitted message has address FFFF and a channel. All modules with any address and the same channel of the message will receive it.
     

   • Fixed transmission monitoring
     The receiver has adress FFFF and a channel. It will receive messages from all modules with any address and the same channel as the receiver.

The module can only be configured when in sleep operating mode (M0 high & M1 high). The UART baudrate has to be 9600 and parity 8N1.

(*) Default configuration bytes for E32-868T20D : C0 00 00 1A 06 44
(**) Default version bytes for E32-868T20D : C3 45 0D 14

To make sense of the different communication pins of the E32 LoRa module, a simple USB logic analyzer and an opensource software comes to the rescue :)
I looked at these scenario's :

1. Transparent transmission
   The device is in normal mode (M0 and M1 both low). Some time after the message data is received on the RXD pin of the module, the AUX pin goes low. The AUX pin stays low until all data has been transmitted by the LoRa radio, after which it goes high again.

2. Fixed transmission in normal mode
   The device is in normal mode (M0 and M1 both low). Some time after the message data is received on the RXD pin of the module, the AUX pin goes low. The message is prefixed with the address and channel info. The AUX pin stays low until all data has been transmitted by the LoRa radio, after which it goes high again.

3. Fixed transmission in wakeup mode
   The device is in wakeup mode (M0 high, M1 low). Some time after the message data is received on the RXD pin of the module, the AUX pin goes low. The message is prefixed with the preamble wakeup signal, the address and channel info. The AUX pin stays low until all data has been transmitted by the LoRa radio, after which it goes high again.

4. Receiving
   The device is in normal mode (M0 and M1 both low). When the LoRa radio receives a signal, the AUX pin goes low. The AUX pin stays low until all data has been sent to the TXD pin, after which it goes high again.

5. Command set config with persistent save
   The device is in sleep mode (both M0 and M1 high). Some time after the set config command is received on the RXD pin of the module, the AUX pin goes low. After the config response is sent to the TXD pin, the AUX pin goes high.

6. Command set config with temporary save
   The device is in sleep mode (both M0 and M1 high). Some time after the set config command is received on the RXD pin of the module, the AUX pin goes low. After the config response is sent to the TXD pin, the AUX pin goes high.

7. Command get config
   The device is in sleep mode (both M0 and M1 high). Some time after the get config command is received on the RXD pin of the module, the AUX pin goes low. After the config response is sent to the TXD pin, the AUX pin goes high.

8. Command get version
   The device is in sleep mode (both M0 and M1 high). Some time after the get version command is received on the RXD pin of the module, the AUX pin goes low. After the version response is sent to the TXD pin, the AUX pin goes high.

9. Command reset device
   The device is in sleep mode (both M0 and M1 high). Some time after the reset command is received on the RXD pin of the module, the AUX pin goes low and stays low while the device is resetting. After the module is ready again, the AUX pin goes high.
   

• Because both the ESP32 and the E32 LoRa module are 3.3V compliant, no voltage dividers are necessary for communication.
• To stabilize the power supply for the E32 LoRa module, an electrolytic capacitor of 100 µF is placed on the power rail of the breadboard.

class ebyteE32:
    ''' class to interface an ESP32 via serial commands to the EBYTE E32 Series LoRa modules '''

def __init__(self, PinM0, PinM1, PinAUX, Model='868T20D', Port='U1', Baudrate=9600, Parity='8N1', AirDataRate='2.4k', Address=0x0000, Channel=0x06, debug=False):
    ''' constructor for ebyte E32 LoRa module '''

def start(self):
    ''' Start the ebyte E32 LoRa module '''

def sendMessage(self, to_address, to_channel, payload, useChecksum=False):
    ''' Send the payload to ebyte E32 LoRa modules in transparent or fixed mode. The payload is a data dictionary to
        accomodate key value pairs commonly used to store sensor data and is converted to a JSON string before sending.
        The payload can be appended with a 2's complement checksum to validate correct transmission.
        - transparent mode : all modules with the same address and channel of the transmitter will receive the payload
        - fixed mode : only the module with this address and channel will receive the payload;
                        if the address is 0xFFFF all modules with the same channel will receive the payload'''

def recvMessage(self, from_address, from_channel, useChecksum=False):
    ''' Receive payload messages from ebyte E32 LoRa modules in transparent or fixed mode. The payload is a JSON string
        of a data dictionary to accomodate key value pairs commonly used to store sensor data. If checksumming is used, the
        checksum of the received payload including the checksum byte should result in 0 for a correct transmission.
        - transparent mode : payload will be received if the module has the same address and channel of the transmitter
        - fixed mode : only payloads from transmitters with this address and channel will be received;
                           if the address is 0xFFFF, payloads from all transmitters with this channel will be received'''

def calcChecksum(self, payload):
    ''' Calculates checksum for sending/receiving payloads. Sums the ASCII character values mod256 and returns
        the lower byte of the two's complement of that value in hex notation. '''

def reset(self):
    ''' Reset the ebyte E32 Lora module '''

def stop(self):
    ''' Stop the ebyte E32 LoRa module '''

def sendCommand(self, command):
    ''' Send a command to the ebyte E32 LoRa module. The module has to be in sleep mode '''

def getVersion(self):
    ''' Get the version info from the ebyte E32 LoRa module '''

def getConfig(self):
    ''' Get config parameters from the ebyte E32 LoRa module '''

def decodeConfig(self, message):
    ''' decode the config message from the ebyte E32 LoRa module to update the config dictionary '''

def encodeConfig(self):
    ''' encode the config dictionary to create the config message of the ebyte E32 LoRa module '''

def showConfig(self):
    ''' Show the config parameters of the ebyte E32 LoRa module on the shell '''

def waitForDeviceIdle(self):
    ''' Wait for the E32 LoRa module to become idle (AUX pin high) '''

def saveConfigToJson(self):
    ''' Save config dictionary to JSON file ''' 

def loadConfigFromJson(self):
    ''' Load config dictionary from JSON file ''' 

def calcFrequency(self):
    ''' Calculate the frequency (= minimum frequency + channel * 1MHz)''' 

def setTransmissionMode(self, transmode):
    ''' Set the transmission mode of the E32 LoRa module '''

def setConfig(self, save_cmd):
    ''' Set config parameters for the ebyte E32 LoRa module '''

def setOperationMode(self, mode):
    ''' Set operation mode of the E32 LoRa module '''

class ebyteE32 code

To validate the proper working of the ebyteE32 micropython class this simple sensor measuring scenario has been implemented :

1. Sensor nodes

   • each sensor node contains an ESP32 microcontroller, an Ebyte E32 LoRa module, a sensor and a 3.3V power supply with integrated 18650 Li-ion battery.
   • the node wakes up every 5 minutes, takes a sensor reading and transmits it with the E32 LoRa module. Then it goes to deepsleep to extend the battery life.
   • all sensor nodes transmit on the same LoRa channel, but can have different addresses.
   • sensor node 01 has a DHT11 temperature and humidity sensor (code)
   • sensor node 02 has a BMP180 temperature and pressure sensor (code)

2. Monitor node (code)

   • this node contains an ESP32 microcontroller and an Ebyte E32 LoRa module. It is powered 24/7 with a 5V USB supply.
   • the E32 LoRa module is configured as a fixed monitor device (address 0xFFFF) and receives all transmissions from sensor node(s) with the same channel.
   • the incoming sensor data is stored in a Influxdb database table. The sensor data from each sensor node is stored in it's own database table.
   • the Influxdb database runs on a PC on the local network; the monitor node updates the database via a WiFi connection to the same local network.

   Receiving fixed monitor : 
   address 1 - channel 2 - message {'pres': '101860', 'temp': '25', 'node': '02'}
   204
   ..................
   Receiving fixed monitor : 
   address 1 - channel 2 - message {'hum': '21', 'temp': '24', 'node': '01'}
   204
   ..............................................
   Receiving fixed monitor : 
   address 1 - channel 2 - message {'pres': '101852', 'temp': '25', 'node': '02'}
   204
   ..................
   Receiving fixed monitor : 
   address 1 - channel 2 - message {'hum': '20', 'temp': '25', 'node': '01'}
   204
   ..............................................
   Receiving fixed monitor : 
   address 1 - channel 2 - message {'pres': '101850', 'temp': '25', 'node': '02'}
   204
   ..................
   Receiving fixed monitor : 
   address 1 - channel 2 - message {'hum': '20', 'temp': '25', 'node': '01'}
   204
   ..............................................
   Receiving fixed monitor : 
   address 1 - channel 2 - message {'pres': '101853', 'temp': '25', 'node': '02'}
   204
   

3. Influxdb server

   • the Influxdb database server runs on a Linux Mint 19 PC on the local network.
   • dbhost : IP address of Linux PC
   • database : serre_frank
   • fields : time - field - value
   • table : node_01 (DHT11)

       > select * from node_01
       name: node_01
       time		    field	value
       ----		    -----	-----
       1586888687213847522	    hum	        27
       1586888687213847522	    temp	12
       1586889000758763606	    hum	        27
       1586889000758763606	    temp	11
       ...
       1586951625631028963	    hum	        12
       1586951625631028963	    temp	41
       1586951939053618579	    hum	        12
       1586951939053618579	    temp	41
   

   • table : node_02 (BMP180)

       > select * from node_02
       name: node_02
       time		    field	value
       ----		    -----	-----
       1588858703347986765     pres	101987
       1588858703347986765	    temp	26
       1588858809623716125	    pres	101992
       1588858809623716125	    temp	26
       ...
       1588871763234526547	    pres	101853
       1588871763234526547	    temp	25
       1588872076830457467	    pres	101854
       1588872076830457467	    temp	25
   

4. Grafana server

   • the sensor data from the Influxdb table(s) is visualised on a Grafana dashboard. The Grafana server is running on the same Linux Mint 19 PC on the local network.
   • dashboard : Serre Frank
   • panel 1 : Temperature
     
   • panel 2 : Humidity
     
   • panel 3 : Pressure