LoRa E32 Device for Arduino, ESP32 or ESP8266: Library

I create a library to manage EBYTE E32 based on Semtech series of LoRa device, very powerfull, simple and cheap device.

You can find 3Km version here, 8Km version here

They can work over a distance of 3000m to 8000m, and they have a lot of features and parameter.

So I create this library to simplify the usage.

Library

You can find my library here.

To download.

Click the DOWNLOADS button in the top right corner, rename the uncompressed folder LoRa_E32.

Check that the LoRa_E32 folder contains LoRa_E32.cpp and LoRa_E32.h.

Place the LoRa_E32 library folder your /libraries/ folder.

You may need to create the libraries subfolder if its your first library.

Restart the IDE.

Pinout

You can buy here

As you can see you can set various modes via M0 and M1 pins.

There are some pins that can be use in a static way, but If you connect It to the microcontroller and configure they in the library you gain in performance and you can control all mode via software, but we are going to explain better next.

Fully connected schema

As I already say It’s not important to connect all pin to the output of microcontroller, you can put M0 and M1 pins to HIGH or LOW to get desidered configuration, and if you don’t connect AUX the library set a reasonable delay to be sure that the operation is complete.

AUX pin

When transmitting data can be used to wake up external MCU and return HIGH on data transfer finish.

When receiving AUX going LOW and return HIGH when buffer is empty.

It’s also used for self checking to restore normal operation (on power-on and sleep/program mode).

esp8266 connection schema is more simple because It work at the same voltage of logical communications (3.3v).

It’s important to add pull-up resistor (4, 7Kohm) to get good stability.

Arduino working voltage is 5v, so we need to add a voltage divider on RX pin M0 and M1 of LoRa module to prevent damage, you can get more information here Voltage divider: calculator and application.

You can use a 2Kohm resistor to GND and 1Kohm from signal than put together on RX.

Constructor

I made a set of quite numerous constructors, because we can have more options and situations to manage.

LoRa_E32(byte rxPin, byte txPin, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);
LoRa_E32(byte rxPin, byte txPin, byte auxPin, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);
LoRa_E32(byte rxPin, byte txPin, byte auxPin, byte m0Pin, byte m1Pin, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);

First set of constructor are create to delegate the manage of Serial and other pins to the library.

rxPin and txPin is the pin to connect to UART and they are mandatory.

auxPin is a pin that check the operation, transmission and receiving status (we are going to explain better next), that pin It isn’t mandatory, if you don’t set It I apply a delay to permit the operation to complete itself (with latency).

m0pin and m1Pin are the pins to change operation MODE (see the table upper), I think this pins in “production” are going to connect directly HIGH or LOW, but for test they are usefully to be managed by the library.

bpsRate is the boudrate of SoftwareSerial normally is 9600 (the only baud rate in programmin/sleep mode)

A simple example is

#include "LoRa_E32.h"
LoRa_E32 e32ttl100(2, 3); // RX, TX
// LoRa_E32 e32ttl100(2, 3, 5, 6, 7); // RX, TX

We can use directly a SoftwareSerial with another constructor

LoRa_E32(HardwareSerial* serial, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);
LoRa_E32(HardwareSerial* serial, byte auxPin, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);
LoRa_E32(HardwareSerial* serial, byte auxPin, byte m0Pin, byte m1Pin, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);

The example upper with this constructor can be do like so.

#include <SoftwareSerial.h>
#include "LoRa_E32.h"
SoftwareSerial mySerial(2, 3); // RX, TX
LoRa_E32 e32ttl100(&amp;mySerial);
// LoRa_E32 e32ttl100(&amp;mySerial, 5, 7, 6);

The last set of constructor is to permit to use an HardwareSerial instead of SoftwareSerial.

LoRa_E32(SoftwareSerial* serial, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);
LoRa_E32(SoftwareSerial* serial, byte auxPin, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);
LoRa_E32(SoftwareSerial* serial, byte auxPin, byte m0Pin, byte m1Pin, UART_BPS_RATE bpsRate = UART_BPS_RATE_9600);

Begin

The begin command is used to startup Serial and pins in input and output mode.

void begin();

in execution is

// Startup all pins and UART
e32ttl100.begin();

Configuration and information method

There a set of methods for manage configuration and get information of the device.

ResponseStructContainer getConfiguration();
ResponseStatus setConfiguration(Configuration configuration, PROGRAM_COMMAND saveType = WRITE_CFG_PWR_DWN_LOSE);
ResponseStructContainer getModuleInformation();
void printParameters(struct Configuration configuration);
ResponseStatus resetModule();

Response container

To simplify the manage of response I create a set of container, for me very usefully to manage errors and return generic data.

ResponseStatus

This is a status container and have 2 simple entry point, with this you can get the status code and the description of status code

Serial.println(c.getResponseDescription()); // Description of code
Serial.println(c.code); // 1 if Success

The code are

SUCCESS = 1,
ERR_UNKNOWN,
ERR_NOT_SUPPORT,
ERR_NOT_IMPLEMENT,
ERR_NOT_INITIAL,
ERR_INVALID_PARAM,
ERR_DATA_SIZE_NOT_MATCH,
ERR_BUF_TOO_SMALL,
ERR_TIMEOUT,
ERR_HARDWARE,
ERR_HEAD_NOT_RECOGNIZED

ResponseContainer

This container is created to manage String response and have 2 entry point.

data with the string returned from message and status an instance of RepsonseStatus.

ResponseContainer rs = e32ttl.receiveMessage();
String message = rs.data;
Serial.println(rs.status.getResponseDescription());
Serial.println(message);

ResponseStructContainer

This is the more “complex” container, I use this to manage structure, It has the same entry point of ResponseContainer but data is a void pointer to manage complex structure.

ResponseStructContainer c;
c = e32ttl100.getConfiguration();
// It's important get configuration pointer before all other operation
Configuration configuration = *(Configuration*) c.data;
Serial.println(c.status.getResponseDescription());
Serial.println(c.status.code);

getConfiguration and setConfiguration

The first method is getConfiguration, you can use It to retrive all data stored on device.

ResponseStructContainer getConfiguration();

Here an usage example.

ResponseStructContainer c;
c = e32ttl100.getConfiguration();
// It's important get configuration pointer before all other operation
Configuration configuration = *(Configuration*) c.data;
Serial.println(c.status.getResponseDescription());
Serial.println(c.status.code);
Serial.println(configuration.SPED.getUARTBaudRate());

Structure of configuration have all data of settings, and I add a series of function to get all description of single data.

configuration.ADDL = 0x0; // First part of address
configuration.ADDH = 0x1; // Second part of address
configuration.CHAN = 0x19;// Channel
configuration.OPTION.fec = FEC_0_OFF; // Forward error correction switch
configuration.OPTION.fixedTransmission = FT_TRANSPARENT_TRANSMISSION; // Transmission mode
configuration.OPTION.ioDriveMode = IO_D_MODE_PUSH_PULLS_PULL_UPS; // Pull-up management
configuration.OPTION.transmissionPower = POWER_17; // dBm transmission power
configuration.OPTION.wirelessWakeupTime = WAKE_UP_1250; // Wait time for wake up
configuration.SPED.airDataRate = AIR_DATA_RATE_011_48; // Air data rate
configuration.SPED.uartBaudRate = UART_BPS_115200; // Communication baud rate
configuration.SPED.uartParity = MODE_00_8N1; // Parity bit

You have the equivalent function for all attribute to get all description:

Serial.print(F("Chan : "));  Serial.print(configuration.CHAN, DEC); Serial.print(" -> "); Serial.println(configuration.getChannelDescription());
Serial.println(F(" "));
Serial.print(F("SpeedParityBit     : "));  Serial.print(configuration.SPED.uartParity, BIN);Serial.print(" -> "); Serial.println(configuration.SPED.getUARTParityDescription());
Serial.print(F("SpeedUARTDatte  : "));  Serial.print(configuration.SPED.uartBaudRate, BIN);Serial.print(" -> "); Serial.println(configuration.SPED.getUARTBaudRate());
Serial.print(F("SpeedAirDataRate   : "));  Serial.print(configuration.SPED.airDataRate, BIN);Serial.print(" -> "); Serial.println(configuration.SPED.getAirDataRate());
Serial.print(F("OptionTrans        : "));  Serial.print(configuration.OPTION.fixedTransmission, BIN);Serial.print(" -> "); Serial.println(configuration.OPTION.getFixedTransmissionDescription());
Serial.print(F("OptionPullup       : "));  Serial.print(configuration.OPTION.ioDriveMode, BIN);Serial.print(" -> "); Serial.println(configuration.OPTION.getIODroveModeDescription());
Serial.print(F("OptionWakeup       : "));  Serial.print(configuration.OPTION.wirelessWakeupTime, BIN);Serial.print(" -> "); Serial.println(configuration.OPTION.getWirelessWakeUPTimeDescription());
Serial.print(F("OptionFEC          : "));  Serial.print(configuration.OPTION.fec, BIN);Serial.print(" -> "); Serial.println(configuration.OPTION.getFECDescription());
Serial.print(F("OptionPower        : "));  Serial.print(configuration.OPTION.transmissionPower, BIN);Serial.print(" -> "); Serial.println(configuration.OPTION.getTransmissionPowerDescription());

At same way setConfiguration want a configuration strucutre, so I think the better way to manage configuration is to retrieve the current one, apply the only change you need and set It again.

ResponseStatus setConfiguration(Configuration configuration, PROGRAM_COMMAND saveType = WRITE_CFG_PWR_DWN_LOSE);

configuration is the strucutre previsiouly show, saveType permit to you to choiche if the change become permanently of only for the current session.

ResponseStructContainer c;
c = e32ttl100.getConfiguration();
// It's important get configuration pointer before all other operation
Configuration configuration = *(Configuration*) c.data;
Serial.println(c.status.getResponseDescription());
Serial.println(c.status.code);
printParameters(configuration);
configuration.ADDL = 0x0;
configuration.ADDH = 0x1;
configuration.CHAN = 0x19;
configuration.OPTION.fec = FEC_0_OFF;
configuration.OPTION.fixedTransmission = FT_TRANSPARENT_TRANSMISSION;
configuration.OPTION.ioDriveMode = IO_D_MODE_PUSH_PULLS_PULL_UPS;
configuration.OPTION.transmissionPower = POWER_17;
configuration.OPTION.wirelessWakeupTime = WAKE_UP_1250;
configuration.SPED.airDataRate = AIR_DATA_RATE_011_48;
configuration.SPED.uartBaudRate = UART_BPS_115200;
configuration.SPED.uartParity = MODE_00_8N1;
// Set configuration changed and set to not hold the configuration
ResponseStatus rs = e32ttl100.setConfiguration(configuration, WRITE_CFG_PWR_DWN_LOSE);
Serial.println(rs.getResponseDescription());
Serial.println(rs.code);
printParameters(configuration);

The parameter are all managed as constant:

Basic configuration option

SPED detail

UART Parity bit: UART mode can be different between communication parties

UART baud rate: UART baud rate can be different between communication parties, The UART baud rate has nothing to do with wireless transmission parameters & won’t affect the wireless transmit / receive features.

Air data rate: The lower the air data rate, the longer the transmitting distance, better anti- interference performance and longer transmitting time, The air data rate must keep the same for both communication parties.

OPTION detail

Transmission mode: in fixed transmission mode, the first three bytes of each user’s data frame can be used as high/low address and channel. The module changes its address and channel when transmit. And it will revert to original setting after complete the process.

IO drive mode: this bit is used to the module internal pull- up resistor. It also increases the level’s adaptability in case of open drain. But in some cases, it may need external pull-up resistor.

Wireless wake-up time: the transmit & receive module work in mode 0, whose delay time is invalid & can be arbitrary value, The transmitter works in mode 1 can transmit the preamble code of the corresponding time continuously, when the receiver works in mode 2, the time means the monitor interval time (wireless wake-up). Only the data from transmitter that works in mode 1 can be received.

FEC: after turn off FEC, the actual data transmission rate increases while anti- interference ability decreases. Also the transmission distance is relatively short, both communication parties must keep on the same pages about turn-on or turn-off FEC.

Transmission power

You can change this set of constant by apply a define like so:

#define E32_TTL_100 // default value without set

Applicable for E32-TTL-100, E32-TTL-100S1, E32-T100S2. The external power must make sure the ability of current output more than 250mA and ensure the power supply ripple within 100mV. Low power transmission is not recommended due to its low power supply efficiency.

#define E32_TTL_100 // default value without set

Applicable for E32-TTL-500。 The external power must make sure the ability of current output more than 700mA and ensure the power supply ripple within 100mV. Low power transmission is not recommended due to its low power supply efficiency.

#define E32_TTL_500

Applicable for E32-TTL-1W, E32 (433T30S), E32 (868T30S), E32 (915T30S) The external power must make sure the ability of current output more than 1A and ensure the power supply ripple within 100mV. Low power transmission is not recommended due to its low power supply efficiency.

#define E32_TTL_1W

You can configure Channel frequency olso with this define:

// One of
#define FREQUENCY_433
#define FREQUENCY_170
#define FREQUENCY_470
#define FREQUENCY_868
#define FREQUENCY_915

Send receive message

First we must introduce a simple but usefully method to check if something is in the receiving buffer

int available();

It’s simply return how many bytes you have in the current stream.

Normal transmission mode

Normal/Transparent transmission mode is used to send messages to all device with same address and channel.

There are a lot of method to send/receive message, we are going to explain in detail:

ResponseStatus sendMessage(const String message);
ResponseContainer receiveMessage();

First method is sendMessage and is used to send a String to a device in Normal mode.

ResponseStatus rs = e32ttl.sendMessage("Prova");
Serial.println(rs.getResponseDescription());

The other device simply do on the loop

if (e32ttl.available()  > 1){
ResponseContainer rs = e32ttl.receiveMessage();
String message = rs.data; // First ever get the data
Serial.println(rs.status.getResponseDescription());
Serial.println(message);
}

Manage structure

If you want send a complex strucuture you can use this method

ResponseStatus sendMessage(const void *message, const uint8_t size);
ResponseStructContainer receiveMessage(const uint8_t size);

It’s used to send strucutre, for example:

struct Messaggione {
char type[5];
char message[8];
bool mitico;
};
struct Messaggione messaggione = {"TEMP", "Peple", true};
ResponseStatus rs = e32ttl.sendMessage(&messaggione, sizeof(Messaggione));
Serial.println(rs.getResponseDescription());

and the other side you can receive the message so

ResponseStructContainer rsc = e32ttl.receiveMessage(sizeof(Messaggione));
struct Messaggione messaggione = *(Messaggione*) rsc.data;
Serial.println(messaggione.message);
Serial.println(messaggione.mitico);

Read partial strucure

If you want read first part of the message to manage more type of strucutre you can use this method.

ResponseContainer receiveInitialMessage(const uint8_t size);

I create It to receive a string with type or other to identify the strucuture to load.

struct Messaggione { // Partial strucutre without type
char message[8];
bool mitico;
};
char type[5]; // first part of structure
ResponseContainer rs = e32ttl.receiveInitialMessage(sizeof(type));
// Put string in a char array (not needed)
memcpy ( type, rs.data.c_str(), sizeof(type) );
Serial.println("READ TYPE: ");
Serial.println(rs.status.getResponseDescription());
Serial.println(type);
// Read the rest of structure
ResponseStructContainer rsc = e32ttl.receiveMessage(sizeof(Messaggione));
struct Messaggione messaggione = *(Messaggione*) rsc.data;

Fixed mode instead of normal mode

At same manner I create a set of method to use with fixed transmission

Fixed transmission

You need to change only the sending method, because the destination device don’t receive the preamble with Address and Channel quando settato il fixed mode.

So for String message you have

ResponseStatus sendFixedMessage(byte ADDL, byte ADDH, byte CHAN, const String message);
ResponseStatus sendBroadcastFixedMessage(byte CHAN, const String message);

and for structure you have

ResponseStatus sendFixedMessage(byte ADDL, byte ADDH, byte CHAN, const void *message, const uint8_t size);
ResponseStatus sendBroadcastFixedMessage(byte CHAN, const void *message, const uint8_t size );

Here a simple example

ResponseStatus rs = e32ttl.sendFixedMessage(0, 0, 0x17, &messaggione, sizeof(Messaggione));
//	ResponseStatus rs = e32ttl.sendFixedMessage(0, 0, 0x17, "Ciao");

Fixed transmission have more scenarios

LoRa E32 transmitting scenarios, lines are channels

If you send to a specific device (second scenarios Fixed transmission) you must add ADDL, ADDH and CHAN to identify It directly.

ResponseStatus rs = e32ttl.sendFixedMessage(2, 2, 0x17, "Message to a device");

If you want send a message to all device in a specified Channel you can use this method.

ResponseStatus rs = e32ttl.sendBroadcastFixedMessage(0x17, "Message to a devices of a channel");

If you want receive all broadcast message in the network you must set your ADDH and ADDL with BROADCAST_ADDRESS.

ResponseStructContainer c;
c = e32ttl100.getConfiguration();
// It's important get configuration pointer before all other operation
Configuration configuration = *(Configuration*) c.data;
Serial.println(c.status.getResponseDescription());
Serial.println(c.status.code);
printParameters(configuration);
configuration.ADDL = BROADCAST_ADDRESS;
configuration.ADDH = BROADCAST_ADDRESS;
// Set configuration changed and set to not hold the configuration
ResponseStatus rs = e32ttl100.setConfiguration(configuration, WRITE_CFG_PWR_DWN_LOSE);
Serial.println(rs.getResponseDescription());
Serial.println(rs.code);
printParameters(configuration);

Thanks

Now you have all information to do your work, but I think It’s important to show some realistic examples to undestand better all the possibility.

• LoRa E32 device for Arduino, esp32 or esp8266: settings and basic usage
• LoRa E32 device for Arduino, esp32 or esp8266: library
• LoRa E32 device for Arduino, esp32 or esp8266: configuration
• LoRa E32 device for Arduino, esp32 or esp8266: fixed transmission
• LoRa E32 device for Arduino, esp32 or esp8266: power saving and sending structured data