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RFM22B

Page last updated 13 Mar 2013, by Karl Zweimüller. 14 replies HOPERF, Mesh, RF22, RFM22, RFM22B, router, transceiver, wireless

Tests with HOPE RFM22B (V2.0) Transceiver Module

and Porting arduino-Software for the following communication-methods:

RF22: unaddressed, unreliable messages
RF22Datagram: addressed, unreliable messages
RF22ReliableDatagram: addressed, reliable, retransmitted, acknowledged messages.
RF22Router: multi hop delivery from source node to destination node via 0 or more intermediate nodes
RF22Mesh: multi hop delivery with automatic route discovery and rediscovery.

Info

See http://www.hoperf.com

Images

RFM22-Module:

/media/uploads/charly/_scaled_rfm22.jpg

RFM22 with mbed:

/media/uploads/charly/_scaled_rfm22_with_mbed.jpg

RFM22 with LPCmini:

/media/uploads/charly/_scaled_rfm22_with_lpcmini.jpg

Features (from HopeRF-Homepage)

Frequency Range: 433/868/915MHz ISM bands
Sensitivity = –121 dBm
Output power range:+20 dBm Max
Low Power Consumption
Data Rate = 0.123 to 256 kbps
FSK, GFSK, and OOK modulation
Power Supply = 1.8 to 3.6 V
Ultra low power shutdown mode
Digital RSSI
Wake-up timer
Auto-frequency calibration (AFC)
Power-on-reset (POR)
Antenna diversity and TR switch control
Configurable packet handler
Preamble detector
TX and RX 64 byte FIFOs
Low battery detector
Temperature sensor and 8-bit ADC
–40 to +85 °C temperature range
Integrated voltage regulators
Frequency hopping capability
On-chip crystal tuning
14-PIN DIP & 16-PIN SMD package
Low cost

Available at Sparkfun and many others: http://www.sparkfun.com/products/10153

Problems

There are two Versions of the Module

RFM22B-S1
RFM22B-S2

They have different oscilators and they seem to have different frequency-errors. I combined a -S1 and a -S2 and used 869.50 Hz on one module. ~~I had to adjust the frequency on the other to 869.49 Hz to get a working communication! Maybe the AFC could solve this, but I didn't test this yet.~~

By activating AFC, both modules can use the same frequency as expected!-> Added activation of AFC to library.

Now it works perfect

Connecting

FRM22-PIN	Connect to
ANT	a simple 8cm (868MHz) wire for testing
RX_ANT	GPIO1
TX_ANT	GPIO0
VCC	Vout(3.3V)
GND	GND
GPIO0	TX_ANT
GPIO1	RX_ANT
GPIO2
SDN	GND
NIRQ	Interrupt (p15)
NSEL	Chip-Select (p14)
SCK	SPI-SCK (p13)
SDI	SPI-MOSI(p11)
SDO	SPI-MISO(p12)

Software

Original Software for arduino (c) by Mike McCauley

See http://www.open.com.au/mikem/arduino/RF22/

Software under Open Source Licensing GPL V2 - see http://www.open.com.au/mikem/arduino/RF22/

Port to mbed by Karl Zweimueller

Library:

Import library RF22

Library for HopeRF RFM22 / RFM22B transceiver module ported to mbed. Original Software from Mike McCauley (mikem@open.com.au) . See http://www.open.com.au/mikem/arduino/RF22/

Test program for ReliableDatagram Receive

main.c

#include "mbed.h"
#include <RF22.h>
#include <RF22ReliableDatagram.h>

// Sample programm for ReliableDatagramm Receiving
// Uses address 2 and receives from Sender
// See notebook http://mbed.org/users/charly/notebook/rfm22/ for connecting RFM22 to mbed

Serial pc(USBTX, USBRX);

//RF22ReliableDatagram (uint8_t thisAddress, PinName slaveSelectPin, PinName mosi, PinName miso, PinName sclk, PinName interrupt)
RF22ReliableDatagram rf22(0,p14,p11,p12,p13,p15);


float frequency = 869.50;           // frequency 

const uint8_t sender_adress = 1;        // address of sender
const uint8_t receiver_adress =2;       // address of receiver

void receive_loop() {
    while (1) {
        uint8_t buf[RF22_MAX_MESSAGE_LEN];
        uint8_t len = sizeof(buf);

        //boolean recvfromAck(uint8_t* buf, uint8_t* len, uint8_t* from = NULL, uint8_t* to = NULL, uint8_t* id = NULL, uint8_t* flags = NULL);
        if (rf22.recvfromAck(buf, &len)) {
            pc.printf("got message: >%s<\n\r",(char*)buf);
        }
    }
}

int main() {

    pc.baud(115200);
    pc.printf("\n\rConnected to mbed\n\r");

    pc.printf ("RF22-Test-Reliable-Receive V1.0\n\r");

    // initialize the device
    if (!rf22.init())
        pc.printf("RF22 init failed\n\r");

    // set to 19.2 KB
    if (!rf22.setModemConfig(RF22::GFSK_Rb19_2Fd9_6))
        pc.printf("setModemConfig failed");


    if (!rf22.setFrequency(frequency))
        pc.printf("setFrequency failed");

    // Code for receiving
    pc.printf("I am receiving with address %i ...\n\r",receiver_adress);
    rf22.setThisAddress(receiver_adress);     // receiver-adress

    receive_loop();             // start receiving
}

Test program for ReliableDatagram Send

main.c

#include "mbed.h"
#include <RF22.h>
#include <RF22ReliableDatagram.h>

// Sample programm for ReliableDatagramm Sending
// Uses address 1 and sends to RF22 with address 2
// See notebook http://mbed.org/users/charly/notebook/rfm22/ for connecting RFM22 to mbed

Serial pc(USBTX, USBRX);

//RF22ReliableDatagram (uint8_t thisAddress, PinName slaveSelectPin, PinName mosi, PinName miso, PinName sclk, PinName interrupt)
RF22ReliableDatagram rf22(0,p14,p11,p12,p13,p15);

float frequency = 869.50;           // frequency 

const uint8_t sender_adress = 1;        // address of sender
const uint8_t receiver_adress =2;       // address of receiver

int   counter = 0;                      // messagecounter

// send messages forever
void send_loop() {
    uint8_t data[32] = "";

    while (1) {

        sprintf((char*)data,"Message-Nr:     %d",counter++);
        //sendtoWait(uint8_t* buf, uint8_t len, uint8_t address);
        pc.printf("\n\rStart sending ... ");
        if (rf22.sendtoWait(data, sizeof(data), receiver_adress)) {
            pc.printf("Send to %i ACK: >>%s<< ", receiver_adress,(char*)data);
        } else {
            pc.printf("Send to %i NOTACK: >>%s<< ", receiver_adress,(char*)data);
        }
        pc.printf("sleeping 2 seconds...  ");
        wait(2);  // Wait 2 Seconds
    }
}

int main() {

    pc.baud(115200);
    pc.printf("\n\rConnected to mbed\n\r");

    pc.printf ("RF22-Test-Reliable-Send V1.0\n\r");

    // initialize the device
    if (!rf22.init())
        pc.printf("RF22 init failed\n\r");

    // set to 19.2 KB
    if (!rf22.setModemConfig(RF22::GFSK_Rb19_2Fd9_6))
        pc.printf("setModemConfig failed");

    if (!rf22.setFrequency(frequency))
        pc.printf("setFrequency failed");

    // Code for sending
    pc.printf("I am sending with address %i to adress %i ...\n\r",sender_adress,receiver_adress  );
    rf22.setThisAddress(sender_adress);     // sender-adress

    send_loop();                // start sending
}

...

History

16.1.2012: Got first version of software working. Communication with RF22-Class on a mbed and a LPCmini with two RFM22B-modules works!

13.2.2012 Ported RF22Datagramm and RF22ReliableDatagramm classes for point to point communication - Quick and dirty! Works between mbed and LPCmini

21.2.2012 Got AFC working (Module RFM22B-S1 and -S2 can communicate without the need to adjust frequency)

13.3.2013 Updated Library to latest version of original Code of Mike

TODO: ... Beautify Ported Code

14 comments on RFM22B:

jim hamblen

# 21 Feb 2012

Sparkfun also has a handy breakout board for the RFM22B-S2 that would be a bit easier to solder pins on for use in a breadboard.

RFm22

steve childress

# 06 May 2012

ever get the other classes ported? Would it be difficult?

Karl Zweimüller

# 08 May 2012

steve childress wrote:

ever get the other classes ported? Would it be difficult?

Hi Steve!

Which other classes? The Library RF22 contains all classes from the original Package from Mike McCauley:

Import library RF22

Library for HopeRF RFM22 / RFM22B transceiver module ported to mbed. Original Software from Mike McCauley (mikem@open.com.au) . See http://www.open.com.au/mikem/arduino/RF22/

I've only worked with

RF22: unaddressed, unreliable messages
RF22Datagram: addressed, unreliable messages
RF22ReliableDatagram: addressed, reliable, retransmitted, acknowledged messages

They work fine!

Charly

Tran Nghia

# 09 Oct 2012

Hi Karl

Have you work with RF22mesh yet? With this library(RF22mesh) , what is max number of nodes we can inplement to create an ad-hoc network

Karl Zweimüller

# 10 Oct 2012

Hi tran nghia!

Tran Nghia wrote:

Hi Karl

Have you work with RF22mesh yet? With this library(RF22mesh) , what is max number of nodes we can inplement to create an ad-hoc network

No, I didn't test with RF22Mesh, only RF22Datagram and RF22ReliableDatagram, which work without problems here.

I had a quick look on the code and found no explicit limit for the number of nodes in the code. So the limit may be the maximum number of nodes to a target, as the route is sent across the mesh in one message. But I didn't cross-check this.

Regards Charly

Tran Nghia

# 11 Oct 2012

Thanks Karl

We have project associating this library, we must work with RF22Mesh and I recommended my senior to use this library but he didn't believe RF22Mesh and RF22Router. He said that RF22Mesh is proper with a few nodes but a lot of nodes

To implement a test with RF22Mesh is quite expensive, hence i want to persuade myseft and my senior of RF22Mesh

So that you know any proof or information to prove the right of RF22Mesh, don't you?

Thanks again

Janie Roberts

# 22 May 2013

Just wanted to say a quick thanks for this port of the RFM22b code to mbed. I've just purchased a couple of RFM22B breakout boards http://modtronicsaustralia.com/shop/rfm22b-s2-rf-transceiver-breakout-board-v2/ and had them communicating in no time.

Keep up the good work - very much appreciated!!

Ray Smith

# 03 Oct 2013

Hi Karl, what is the distance one can transmit using this tranceiver? 400M >?

Karl Zweimüller

# 03 Oct 2013

Hi Ray!

I didn't do special distance tests, but I use the RFM22 inside my house from the basement up to the 2nd floor. And I have concrete floors and brick-walls and closed doors. No problem. I receive all messages. Outside they should do much higher distances. With more power (setTxPower up to 20dBm) 400 meters should be no problem! But it depends.

Charly

steve childress

# 25 Mar 2014

Anyone know of the proper transform from RSSI (0..255) to received power in dBm? There's a chart in the data sheet, but not sure to do with the end case values. Two RFM22's here, < 1m distance, my formula shows -4dBm received, with +17dBm TX. That seems high - should be perhaps 10dB less, from experience. At 150 ft. and many walls in the path, I see -25dBm which is a booming signal. Again maybe 10-20dB less is what I'd expect. Antennas are just wire, half the 1/4 wave they should be.

This is at 433MHz and yes the free space path loss is much less than 900MHz, and very much less than 2.4GHz.

Karl Zweimüller

# 27 Mar 2014

Hi!

I did never calculate the real dBm from the read RSSI-Register-Values. But as you say the only source is the diagram in the datasheet: /media/uploads/charly/rfm22_rssi.png

The datasheet says that the real dBm can be differ because of receiver-settings (Amplifier, AGC,...). Another issue could be the time when you read the RSSI-Value.

But my experience is, that the modules have a good receiver. I use them at 869 Mhz and thy work well between walls and floors. And you can send with a lot of power :-)

Charly

John Kemp

# 19 Dec 2014

Hi Karl, you did a amazing job!! I only spent half a day to make it working on my boards(stm32f407 and RF22). But I got a problem when I tried to drive two RF22 on just one board. it seems didn't work with multiple RF22 at the same time. I wonder if it's caused by "disable_irq()" and " enable_irq()" as of two RF22s using different interrupts. I replaced them with "_interrupt.disable_irq()" and "_interrupt.enable_irq()", it didn't work too. Would you please give me some advises, about how to connect two more RF22s to one board?

Thanks a lot!

Karl Zweimüller

# 12 Jan 2015

Hello John!

Sorry, but I didn't see your comment. I've never tried to connect 2 RFM22, but I can think that it makes problems. The protected sections are required to prevent parallel change of one ressource.

Do you use one SPI-Interface or two? I'm not sure if it is possible to define 2 SPI-Objects for the same lines. You use 2 interrupt-lines. And I think two different Chip-Select-Lines too. If not, this could be a problem.

Another issue could be power-consumption. The RFM22 can take a lot of current when sending. And sending on both devices the same time won't be a good idea I think.

When do you get errors? compiletime, initializing, receiving, sending?

I think the library must be adopted to support 2 devices at one time. At the moment I'm working on another project, so I have little time for this issue.

Maybe you can adopt the library and make a pull-request. Then I can integrate to the library.

BTW: What is your usecase for two RFM22? Receiving simultanoiusly on two different frequencies? I think there is an option like channel-hopping, but I'm not sure.

Charly

Antonia Meiye

# 18 Nov 2015

Hi, I would like to test RFM22 with firmware K64.

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RFM22B

Tests with HOPE RFM22B (V2.0) Transceiver Module

Info

Images

Features (from HopeRF-Homepage)

Problems

Connecting

Software

Import libraryRF22

Test program for ReliableDatagram Receive

main.c

Test program for ReliableDatagram Send

main.c

History

14 comments on RFM22B:

steve childress wrote:

Import libraryRF22

Tran Nghia wrote:

RFM22B

Important Information for this Arm website

Access Warning

Import library RF22

Import library RF22