Arduino-LoRa-Ra01S

This is an Arduino library for LoRa Communication using the radio transceiver chips SX1262 and SX1268.

Ai-Thinker offers several LoRa modules.
You can get these on AliExpress and eBay.

Model	Type	Interface/Core	Chip	Frequency	Foot-Pattern	High-Power	LoRa-WAN
Ra-01	Tranceiver	SPI	SX1278	410-525Mhz	SMD16	No	No
Ra-02	Tranceiver	SPI	SX1278	410-525Mhz	SMD16	No	No
Ra-01H	Tranceiver	SPI	SX1276	803-930Mhz	SMD16	No	No
Ra-01S	Tranceiver	SPI	SX1268	410-525Mhz	SMD16	No	No
Ra-01S-P	Tranceiver	SPI	SX1268	410-525Mhz	SMD16	Yes	No
Ra-01SH	Tranceiver	SPI	SX1262	803-930Mhz	SMD16	No	No
Ra-01SH-P	Tranceiver	SPI	SX1262	803-930Mhz	SMD16	Yes	No
Ra-01SC	Tranceiver	SPI	LLCC68	410-525Mhz	SMD16	No	No
Ra-01SC-P	Tranceiver	SPI	LLCC68	410-525Mhz	SMD16	Yes	No
Ra-01SCH	Tranceiver	SPI	LLCC68	803-930Mhz	SMD16	No	No
Ra-01SCH-P	Tranceiver	SPI	LLCC68	803-930Mhz	SMD16	Yes	No
Ra-03SCH	Tranceiver	SPI	LLCC68	803-930Mhz	SMD14	No	No
Ra-06	MCU	ARM Cortex M0+	SX1278	410-525Mhz	SMD20	No	No
Ra-07	MCU	ARM Cortex M0+	ASR6501	410-525Mhz	SMD18	No	Yes
Ra-07H	MCU	ARM Cortex M0+	ASR6501	803-930Mhz	SMD18	No	Yes
Ra-08	MCU	ARM Cortex M4	ASR6601	410-525Mhz	SMD18	No	Yes
Ra-08H	MCU	ARM Cortex M4	ASR6601	803-930Mhz	SMD18	No	Yes

Datasheets for each module can be found here.

Option with SX1262/1268

LoRa modules with SX1262/1268 have several options.

• Using TCXO(Temperature-Compensated Crystal Oscillator)
  SX1262/1268 can use the TCXO.
  If the TCXO is used, the XTB pin is not connected.
  However, the 6th pin (DIO3) of the SX1262/1268 can be used to power the TCXO.
  Explanation for TXCO and antenna control is here.
  Ra-01S / Ra-01SH does not use TCXO.

• Power supply modes
  SX1262/1268 has two power supply modes.
  One is that only LDO used in all modes.
  Another is that DC_DC+LDO used for STBY_XOSC,FS, RX and TX modes.
  Explanation for LDO and DCDC selection is here.
  Ra-01S / Ra-01SH use only LDO in all modes.

• RF-Switching
  In general, use DIO2 to switch the RF-Switch.
  However, some tranceiver use an external gpio to switch the RF-Switch.
  Ra-01S / Ra-01SH use the SC70-6 integrated load switch to switch between RFO and RFI.
  Ra-01S / Ra-01SH use DIO2 to control this.
  DIO2 = 1, CTRL = 0, RFC to RF1 Tx Mode.
  DIO2 = 0, CTRL = 1, RFC to R21 Rx Mode.

You need to look at the schematic to set these options properly, but it's very esoteric.
The default settings for this library are for Ra-01S / Ra-01SH.
When using other than Ra-01S/01SH, you need to set them appropriately.

I created this library based on this.
With this library, Ra-01S/01SH doesn't work.

About LLCC68

LLCC68 is compatible with SX1262/SX1268.
Different between LLCC68 and SX1262/SX1268:
(1) SX1262/SX1268 support spreading factor SF5,SF6,SF7,SF8,SF9,SF10,SF11,SF12.
SX1262/SX1268 can set spreading factor and receiving bandwidth:
LoRa@ Rx/Tx, BW = 7.8 - 500 kHz
SF5 TO SF12,BR=0.018-62.5 Kb/S

(2) LLCC68 support spreading factor SF5,SF6,SF7,SF8,SF9,SF10,SF11.
LLCC68 can set spreading factor and receiving bandwidth:
LoRa@ Rx/Tx, BW = 125 - 250 - 500 kHz
LoRa@ SF=5-6-7-8-9 for BW=125kHz
LoRa@ SF=5-6-7-8-9-10 for BW =250 kHz
LoRa@ SF=5-6-7-8-9-10-11 for BW=500 kHz

When using LLCC68 other than Ra-01SC/01SCH, it is necessary to set the options appropriately based on the datasheet.

Foot pattern

RA-0x(SMD16) has the same foot pattern as ESP12.
Therefore, a pitch conversion PCB for ESP12 can be used.
We have pitch conversion PCBs available on eBay and AliExpress.

Installation

Download this repo as zip. Then in the Arduino IDE go to Sketch->Add library->add .zip library.

Wiring

Ra-01S/SH		UNO	MEGA	ESP8266
VCC	--	3.3V(*1)	3.3V	3.3V
GND	--	GND	GND	GND
SCK	--	D13(*2)	D52(*2)	IO14
MISO	--	D12	D50	IO12
MOSI	--	D11(*2)	D51(*2)	IO13
NSS	--	D5(*2)	D5(*2)	IO2
RST	--	D6(*2)	D6(*2)	IO0
BUSY	--	D7(*2)	D7(*2)	IO16
TXEN	--	N/C	N/C	N/C
RXEN	--	N/C	N/C	N/C

(*1)
UNO's 3.3V output can only supply 50mA.
In addition, the output current capacity of UNO-compatible devices is smaller than that of official products.
So this module may not work normally when supplied from the on-board 3v3.

(*2)
SX126x is not 5V tolerant.
You need level shift from 5V to 3.3V.
I used this for a level shift.

Using EBYTE Module

EBYTE offers several LoRa modules.
You can get these on AliExpress and eBay.

Model	Interface	Chip	Frequency	Power	Foot-Patten	IPEX-Antena	LoRa-WAN
E22-400M22S	SPI	SX1268	433/470Mhz	160mW	Standard	Yes	No
E22-400M30S	SPI	SX1268	433/470Mhz	1000mW	Standard	Yes	No
E22-400MM22S	SPI	SX1268	433/470Mhz	160mW	Small	No	No
E22-900M22S	SPI	SX1262	868/915Mhz	160mW	Standard	Yes	No
E22-900M30S	SPI	SX1262	868/915Mhz	1000mW	Standard	Yes	No
E22-900MM22S	SPI	SX1262	868/915Mhz	160mW	Small	No	No

With this change it work.

/*
SX126x  lora(5,               //Port-Pin Output: SPI select
             6,               //Port-Pin Output: Reset 
             7                //Port-Pin Input:  Busy
             );

int16_t ret = lora.begin(RF_FREQUENCY,              //frequency in Hz
                         TX_OUTPUT_POWER);          //tx power in dBm
*/

SX126x  lora(5,               //Port-Pin Output: SPI select
             6,               //Port-Pin Output: Reset 
             7                //Port-Pin Input:  Busy
             8                //Port-Pin Output: TXEN
             9                //Port-Pin Output: RXEN
             );

int16_t ret = lora.begin(RF_FREQUENCY,              //frequency in Hz
                         TX_OUTPUT_POWER,           //tx power in dBm
                         3.3,                       //use TCXO
                         true);                     //use TCXO

Two additional wires are required.

EBYTE		UNO	MEGA	ESP8266
TXEN	--	8(*3)	8(*3)	D4
RXEN	--	9(*3)	9(*3)	D5

(*3)
SX126x is not 5V tolerant.
You need level shift from 5V to 3.3V.

The pitch conversion base is here.

SX1262 and LLCC68 are compatible, but for some reason they don't work.

Model	Interface	Chip	Frequency	Power	Foot-Patten	IPEX-Antena	LoRa-WAN
E220-400M22S	SPI	LLCC68	433/470Mhz	160mW	Standard	Yes	No
E220-400M30S	SPI	LLCC68	433/470Mhz	1000mW	Standard	Yes	No
E220-900M22S	SPI	LLCC68	868/915Mhz	160mW	Standard	Yes	No
E220-900M30S	SPI	LLCC68	868/915Mhz	1000mW	Standard	Yes	No

Software compatibility

This library can communicate with RadioLib.
RadioLib require DIO1 connected in order to works.

  // Set frequency: 866Mhz
  // Set bandwidth(BW): 125Khz
  // Set Spreading Factor(SF): 7
  // Set Error Cording Rate(CR): 4/5
  // Set SyncWord: 0x1424(Private Network)
  // Set Power: 10dBm
  // Set Preamble Length: 8
  // Configure the radio to NOT use a TCXO controlled by DIO3
  // Set regulator mode: DC-DC
  int state = radio.begin(866.0, 125.0, 7, 5, RADIOLIB_SX126X_SYNC_WORD_PRIVATE, 10, 8, 0.0, false);

Limitation

The SX126x chip supports FSK/GFSK/MSK/GMSK/OOK modulation methods , but these are not supported by this library.

Communication with SX127X

LoRa's packet format is strictly specified.
Therefore, if the following three parameters are the same, they can communicate with each other.

• Signal Bandwidth (= BW)
• Error Cording Rate (= CR)
• Spreading Factor (= SF)

About communication speed and maximum reception sensitivity

In LoRa modulation mode, the communication speed (bps) and maximum reception sensitivity (RSSI) are determined by a combination of spreading factor (SF), bandwidth (BW), and coding rate (CDR).

• SF
  Increasing SF increases the spreading factor and improves noise resistance.
  This improves reception sensitivity and extends communication distance, but communication speed decreases.
• BW
  Bandwidth sets the width of the communication band. Setting a larger bandwidth will improve communication speed.
  However, the radio reception sensitivity (RSSI) will decrease.
• CDR
  CDR (CodingRate) sets the level of error correction rate.
  The larger the number, the better the correction rate, but the amount of information per packet increases.
  (No effect on maximum reception sensitivity)
  You can set whether to use Optimaise for each CDR, and enabling it will improve the correction rate, but will reduce communication speed.

SX1262 and SX1278, SX1276 Comparison

This will be helpful.

Build ESP8266 with PlatformIO

$ git clone https://github.com/nopnop2002/Arduino-LoRa-Ra01S

$ cd Arduino-LoRa-Ra01S/example/Ra01S-RX/

$ pio init -b d1_mini

$ cp Ra01S-RX.ino src/

$ vi src/Ra01S-RX.ino
Disable AtMega
Enable ESP8266

$ vi platform.ini
[env:d1_mini]
platform = espressif8266
board = d1_mini
framework = arduino
lib_deps = https://github.com/nopnop2002/Arduino-LoRa-Ra01S --> Add this line

$ pio run -t upload && pio device monitor -b 115200