LoRa E32 device for Arduino, esp32 or esp8266: library – Part 2

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

LoRa E32-TTL-100

You can find module 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

E32 TTL 100

You can buy here

Pin No. Pin item Pin direction Pin application
1M0Input(weak pull-up)Work with M1 & decide the four operating modes.Floating is not allowed, can be ground.
2M1Input(weak pull-up)Work with M0 & decide the four operating modes.Floating is not allowed, can be ground.
3RXDInputTTL UART inputs, connects to external (MCU, PC) TXD outputpin. Can be configured as open-drain or pull-up input.
4TXDOutputTTL UART outputs, connects to external RXD (MCU, PC) inputpin. Can be configured as open-drain or push-pull output

5

AUX

Output
To indicate module’s working status & wakes up the external MCU. During the procedure of self-check initialization, the pin outputs low level. Can be configured as open-drain output orpush-pull output (floating is allowed).
6VCC
Power supply 2.3V~5.5V DC
7GND
Ground

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

Mode M1 M0 Explanation
Normal00UART and wireless channel is good to go
Wake-Up01Same as normal but a preamble code is added to transmitted data for waking-up the receiver.
Power-Saving10UART is disable and wireless is on WOR(wake on radio) mode which means the device will turn on when there is data to be received. Transmission is not allowed.
Sleep11Used in setting parameters. Transmitting and receiving disabled.

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.

LoRa E32 AUX Pin on transmission

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

LoRa e32 AUX pin on reception

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

LoRa e32 AUX pin on self-check

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

LoRa E32 TTL 100 Wemos D1 fully connected

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

M0D7
M1D6
RXPIN D2 (PullUP 4,7KΩ)
TXPIN D3 (PullUP 4,7KΩ)
AUXD5 (Input)
VCC3.3v
GNDGND

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.

LoRa E32 TTL 100 Arduino fully connected
M07 (Voltage divider)
M16 (Voltage divider)
RXPIN D2 (PullUP 4,7KΩ & Voltage divider)
TXPIN D3 (PullUP 4,7KΩ)
AUX5 (Input)
VCC3.3v
GNDGND

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

ADDHHigh address byte of module (the default 00H)00H-FFH
ADDLLow address byte of module (the default 00H)00H-FFH
SPEDInformation about data rate parity bit and Air data rate
CHANCommunication channel(410M + CHAN*1M), default 17H (433MHz), valid only for 433MHz device chek below to check the correct frequency of your device00H-1FH
OPTIONType of transmission, pull-up settings, wake-up time, FEC, Transmission power

SPED detail

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

76UART parity bitConstant value
008N1 (default)MODE_00_8N1
018O1MODE_01_8O1
108 E1MODE_10_8E1
118N1 (equal to 00)MODE_11_8N1

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.

543TTL UART baud rate(bps) Constant value
0001200UART_BPS_1200
0012400UART_BPS_2400
0104800UART_BPS_4800
0119600 (default)UART_BPS_9600
10019200UART_BPS_19200
10138400UART_BPS_38400
11057600UART_BPS_57600
111115200UART_BPS_115200

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.

210Air data rate(bps) Constant value
0000.3kAIR_DATA_RATE_000_03
0011.2kAIR_DATA_RATE_001_12
0102.4k (default)AIR_DATA_RATE_010_24
0114.8kAIR_DATA_RATE_011_48
1009.6kAIR_DATA_RATE_100_96
10119.2kAIR_DATA_RATE_101_192
11019.2k (same to 101)AIR_DATA_RATE_110_192
11119.2k (same to 101)AIR_DATA_RATE_111_192

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.

7Fixed transmission enabling bit(similar to MODBUS) Constant value
0Transparent transmission modeFT_TRANSPARENT_TRANSMISSION
1Fixed transmission modeFT_FIXED_TRANSMISSION

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.

6IO drive mode ( default 1) Constant value
1TXD and AUX push-pull outputs, RXD pull-up inputsIO_D_MODE_PUSH_PULLS_PULL_UPS
0TXD、AUX open-collector outputs, RXD open-collector inputsIO_D_MODE_OPEN_COLLECTOR

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.

543wireless wake-up time Constant value
000250ms (default)WAKE_UP_250
001500msWAKE_UP_500
010750msWAKE_UP_750
0111000msWAKE_UP_1000
1001250msWAKE_UP_1250
1011500msWAKE_UP_1500
1101750msWAKE_UP_1750
1112000msWAKE_UP_2000

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.

2FEC switch Constant value
0Turn off FECFEC_0_OFF
1Turn on FEC (default)FEC_1_ON

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 
10Transmission power (approximation) Constant value
0020dBm (default)POWER_20
0117dBmPOWER_17
1014dBmPOWER_14
1110dBmPOWER_10

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
10Transmission power (approximation) Constant value
0027dBm (default)POWER_27
0124dBmPOWER_24
1021dBmPOWER_21
1118dBmPOWER_18

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
10Transmission power (approximation) Constant value
0030dBm (default)POWER_30
0127dBmPOWER_27
1024dBmPOWER_24
1121dBmPOWER_21

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.

LoRa E32 transmitting scenarios, lines are channels

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(&amp;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, &amp;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.

  1. LoRa E32 device for Arduino, esp32 or esp8266: settings and basic usage
  2. LoRa E32 device for Arduino, esp32 or esp8266: library
  3. LoRa E32 device for Arduino, esp32 or esp8266: configuration
  4. LoRa E32 device for Arduino, esp32 or esp8266: fixed transmission
  5. LoRa E32 device for Arduino, esp32 or esp8266: power saving and sending structured data
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