Step-by-step procedure to connect the NRF24L01+ to the GPIO pins and use the Raspberry as a Serial Gateway (MySensors 1.x)

mfalkvidd

Note: This guide is only applicable to MySensors 1.x. For MySensors 2, use this guide.

I noticed that a step-by-step procedure to connect the NRF24L01 to the GPIO pins and use the Raspberry as a Serial Gateway was listed in the document for MySensors 1.6.

Since I have three gateways configured this way, and I need to set up 3 more for covering different offices around the world, and I had already written the instructions in Swedish for Datormagazin, I thought I'd help out.

This is the first draft. Any feedback is welcome.

INTRODUCTION
The radio module NRF24L01+ is cheap and power efficient, but it is unable to communicate with regular wifi. The bridge between NRF24L01+ nodes and the "computer world" is called a Gateway. You can use other types of gateways, but connecting the NRF24L01+ module directly to the Raspberry Pi is a simple and cheap alternative.

Wiring Things Up
Connect the NRF20L01+ radio module to the Raspberry Pi like this:
raspi_mysensors[1].png

Raspberry Pi	NRF24L01+	Color
6 / GND	GND	Black
1 / 3.3V DC	VCC	Red
22 / GPIO25	CE	Orange
24 / GPIO 8	CSN/CS	Yellow
23 / GPIO11 / SPI_CLK	SCK	Green
19 / GPIO10 / SPI_MOSI	MOSI	Blue
21 / GPIO9 / SPI_MISO	MISO	Violet

The IRQ pin on NRF24L01 is not currently used.

For a comprehensive view of the Raspberry Pi pins, see http://pinout.xyz/

You should also connect a decoupling capacitor to the radio. See this guide.

COMPILING THE GATEWAY
Login to your Raspberry Pi (using SSH or open a terminal on the graphical console) and run these commands:

git clone https://github.com/TMRh20/RF24.git
cd RF24
make all && sudo make install
cd ..

git clone https://github.com/mysensors/Raspberry.git
cd Raspberry
make all && sudo make install

If you get the following error:

pi@raspberrypi ~/RF24 $ make all && sudo make install
g++ -Wall -fPIC -Ofast -mfpu=vfp -mfloat-abi=hard -mtune=arm1176jzf-s -march=armv7-a -D BCM2835_PERI_BASE=0x -c RF24.cpp
gcc -Wall -fPIC -Ofast -mfpu=vfp -mfloat-abi=hard -mtune=arm1176jzf-s -march=armv7-a -D BCM2835_PERI_BASE=0x -c bcm2835.c
bcm2835.c: In function ‘bcm2835_init’:
bcm2835.c:1207:28: error: invalid suffix "x" on integer constant

You've probably run into the problem discussed in this thread. People have had luck with different solutions. The simplest is to make the following change to ~/Raspberry/librf24-bcm/Makefile

#IOBASE := $(shell cat /proc/iomem | grep bcm2708_vcio | cut -f 1 -d "-")
IOBASE := 3F000000

VERIFY THE GATEWAY
Run sudo /usr/local/sbin/PiGatewaySerial. The output should look like this:

pi@raspberrypi ~/Raspberry $ sudo /usr/local/sbin/PiGatewaySerial
Starting PiGatewaySerial...
Protocol version - 1.4
Created PTY '/dev/pts/1'
Gateway tty: /dev/ttyMySensorsGateway
================ SPI Configuration ================
CSN Pin          = CE0 (PI Hardware Driven)
CE Pin           = Custom GPIO25
Clock Speed      = 8 Mhz
================ NRF Configuration ================
STATUS           = 0x0e RX_DR=0 TX_DS=0 MAX_RT=0 RX_P_NO=7 TX_FULL=0
RX_ADDR_P0-1     = 0xe7e7e7e7e7 0xc2c2c2c2c2
RX_ADDR_P2-5     = 0xff 0xc4 0xc5 0xc6
TX_ADDR          = 0xe7e7e7e7e7
RX_PW_P0-6       = 0x00 0x00 0x20 0x00 0x00 0x00
EN_AA            = 0x3b
EN_RXADDR        = 0x07
RF_CH            = 0x4c
RF_SETUP         = 0x23
CONFIG           = 0x0e
DYNPD/FEATURE    = 0x3f 0x06
Data Rate        = 250KBPS
Model            = nRF24L01+
CRC Length       = 16 bits
PA Power         = PA_LOW

If the NRF24L01+ isn't correctly wired, the following error will be shown

pi@raspberrypi ~ $ sudo /usr/local/sbin/PiGatewaySerial
Starting PiGatewaySerial...
Protocol version - 1.4
Created PTY '/dev/pts/2'
Gateway tty: /dev/ttyMySensorsGateway
check wires

If this happens, double-check your wiring and correct any problems. Press Ctrl+Z and type

sudo killall PiGatewaySerial

to get rid of the non-functioning Gateway. Then run sudo /usr/local/sbin/PiGatewaySerial again

If all is well, exit PiGatewaySerial by pressing Ctrl+C. Then run

sudo /etc/init.d/PiGatewaySerial start

to start the gateway as a background process. Verify that it started correctly by running

sudo cat /dev/ttyMySensorsGateway

You should see the message "Gateway startup complete". Exit by typing Ctrl+C.

MAKE THE GATEWAY AUTOSTART
To make sure the Gateway is started when your Raspberry Pi boots up, run the following command:

sudo make enable-gwserial

Enable the gateway for use with Domoticz
Domoticz (and maybe other home automation systems) has trouble reading from the default path created by PiGatewaySerial. You might need to run the following command:

sudo ln -s /dev/ttyMySensorsGateway /dev/ttyUSB20

And change /etc/rc.local from this

exit 0

to this

ln -s /dev/ttyMySensorsGateway /dev/ttyUSB20
exit 0

OTHER NOTES

The 3.3V power on the Raspberry Pi is rated for a maximum of 50mA. A regular NRF24L01+ only needs 15mA, but if you are using a power amplified version you might exceed what the Raspberry Pi can output. In that case, an external power supply might be required. If you use an external power source gnd must be connected to the Raspberry Pi's gnd.
Connecting the NRF24L01+ directly to your Raspberry Pi will prevent you from using the Raspberry Pi's gpio ports for other things, like a Z-wave board.
A user experienced slow data transfer compared to USB-to-Serial(ttl)<-->MySensors Gateway connection, especially on OTA firmware update. If you think this will cause a problem for you, an ethernet gateway might be a better alternative.

As always, I stand on the shoulders of giants. Related posts:

TROUBLESHOOTING
If you get this error

pi@Domoticz3:~/Raspberry$ sudo /etc/init.d/PiGatewaySerial start
[....] Starting PiGatewaySerial (via systemctl): PiGatewaySerial.serviceFailed to start PiGatewaySerial.service: Unit PiGatewaySerial.service failed to load: No such file or directory.
 failed!

or this error

pi@raspberrypi ~ $ sudo /usr/local/sbin/PiGatewaySerial
sudo: /usr/local/sbin/PiGatewaySerial: command not found

you have probably forgotten to run sudo make install. Read the instructions again, and follow them this time :-) User @sineverba reported that a reboot of the Pi after running make install helped.

ahmedadelhosni

Great and simple.
Is connecting the nrf directly to the pi causes any problems and u need to restart it ?
Thanks.

alexsh1

@ahmedadelhosni said:

Is connecting the nrf directly to the pi causes any problems and u need to restart it ?

No, I have not had any big problems. The problem may only be the nrf24l01+ - I had to have a few changed plus fix the con to make it work. Wiring could be an issue. Also pay attention to CE pin.
CE Pin = Custom GPIO25 (I have Custom GPIO22) - this can be changed by the constructor

Excellent write-up

martinhjelmare

Very nice writeup.

One thing that comes to mind is, the latest rasbian Jessie uses systemd instead of init. It would be good if we could add a systemd unit file to the library and a description here how to use it.

hek

Thanks for the writeup @mfalkvidd. I'll add it to the main site when updating for the 1.6 release.

If someone feel comfortable merging the RPi specific code to the MySensors library in the development branch, let me know. Would've been nice to have one codebase as the RPi code has diverged from Arduino quite a bit since it was created.

A configure/autoconf is also something I'd need help with.

tbully

Great write-up! Should we consider instructions on how to create an init.d start/stop script so it can run as a daemon? I've done this, however, I'm having a hard time getting the output to log to syslog. (would be nice for monitoring/diagnostics purposes) The logging doesn't happen until I stop/kill the service.

pi@homeauto01 ~ $ cat /etc/init.d/PiGatewaySerial
#! /bin/sh
# /etc/init.d/PiGatewaySerial

### BEGIN INIT INFO
# Provides: PiGatewaySerial
# Required-Start: $all
# Required-Stop:
# Should-Start:
# Should-Stop:
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start and stop PiGatewaySerial
# Description: PiGatewaySerial
### END INIT INFO


# The following part carries out specific functions depending on arguments.
case "$1" in
  start)
    echo "Starting PiGatewaySerial"
    /root/Raspberry/PiGatewaySerial 2>&1 | logger &
    ;;
  stop)
    echo "Stopping PiGatewaySerial"
    killall PiGatewaySerial
    ;;
  *)
    echo "Usage: /etc/init.d/PiGatewaySerial {start|stop}"
    exit 1
    ;;
esac

exit 0

martinhjelmare

Doesn't the provided init script in the library already have logging? I didn't get around to testing this setup after my initial attempt failed, so I might be wrong.

https://github.com/mysensors/Raspberry/blob/master/initscripts/PiGatewaySerial

GertSanders

Excellent writeup, double plus plus good !!!

Didi

@mfalkvidd
:+1: :clap:

jkandasa

@mfalkvidd I used direct NRF24l01+ with RPI long ago and I felt slow data transfer compare to USB-to-Serial(ttl)<-->MySensors Gateway connection. especially on OTA firmware update.

mfalkvidd

@jkandasa said:

@mfalkvidd I used direct NRF24l01+ with RPI long ago and I felt slow data transfer compare to USB-to-Serial(ttl)<-->MySensors Gateway connection. especially on OTA firmware update.

Thanks. Let's add that under the other notes section.

Myna

This is a very good work !

Is there anything in place for RFM69 ? Would it be difficult to port the code from arduino to rpi ? (I have never coded on RPI).

Also, do you think any performance difference is involved in managing the radio directly from the RPI, compared to having a dedicated atmega/arduino ? Especially if a controller solution is already running on it?

GertSanders

My experience: the Raspberry 2 indicates usually less then 1% processor, with very occasional maximum peaks to 15%. So I would say, Raspberry 2: no worries. My setup is Domoticz + NRF24based gateway on the same Raspi.

mfalkvidd

My experience is on the same level as @GertSanders's - very low cpu usage.

I don't use RFM69 so unfortunately I have no knowledge about the feasibility to connect it directly to the Raspberry Pi.

tbully

@martinhjelmare said:

Doesn't the provided init script in the library already have logging? I didn't get around to testing this setup after my initial attempt failed, so I might be wrong.

https://github.com/mysensors/Raspberry/blob/master/initscripts/PiGatewaySerial

Ugh! Correct. Also, @mfalkvidd did cover this with his "MAKE THE GATEWAY AUTOSTART" section.....If I only could read! I will test this soon to see how the logging works.

Finally, by enabling ser2net and adding something like this to /etc/ser2net.conf:

5003:raw:600/dev/ttyMySensorsGateway

....you have yourself an Ethernet Gateway! Great stuff! Thanks again!

martinhjelmare

@Myna said:

This is a very good work !

Is there anything in place for RFM69 ? Would it be difficult to port the code from arduino to rpi ? (I have never coded on RPI).

Also, do you think any performance difference is involved in managing the radio directly from the RPI, compared to having a dedicated atmega/arduino ? Especially if a controller solution is already running on it?

I've got no experience myself with rfm69 yet, but I've been thinking about it and searching the web says it should work, connecting the rfm69 to the raspberry pi, for example here:
https://github.com/abouillot/HomeAutomation/tree/master/piGateway

There are also custom pcbs for simplicity, don't know if it's tested though:
https://oshpark.com/profiles/thinkpeace

soward

Perhaps re-word the last note from:

A user experienced data transfer compare to USB-to-Serial(ttl)<-->MySensors Gateway connection. especially on OTA firmware update. If you think this will cause a problem for you, an ethernet gateway might be a better alternative.

to:

A user notes that data transfer speeds are comparable to that of a USB-to-Serial(ttl)<-->MySensors Gateway connections. If you think this may be an issue for your application (e.g. OTA firmware updates), an ethernet gateway might be a better alternative.

thanx,
JpS

mfalkvidd

@soward that wasn't quite the feedback I got, but what I wrote didn't make much sense either so I have corrected it now. Thanks!

minscof

I have a trouble with CPU utilization when I start the gateway : 100% all the time. I use Jessie and not Wheezy on a RPI 2. Does someone can help me to troubleshoot this problem ? I have not add a decoupling capacitor , can it be the reason ?

Solved : see this post

christian

@minscof said:

I have a trouble with CPU utilization when I start the gateway : 100% all the time. I use Jessie and not Wheezy on a RPI 2. Does someone can help me to troubleshoot this problem ? I have not add a decoupling capacitor , can it be the reason ?

This happened to me as well, I mixed up the boards I had at home and discover later it was a B+ and not a RPI2 :-) Maybe you've made the same mistake?

Step-by-step procedure to connect the NRF24L01+ to the GPIO pins and use the Raspberry as a Serial Gateway (MySensors 1.x)

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