Dragino Lora/GPS HAT

Instructions to use the Dragino Lora/GPS HAT on OPOS6ULDev (thanks to RaspberryPi™ compatible connector).

[1]

LoRa™

Setup

• RESET is connected to RPi GPIO0 which is gpio24 on OPOS6UL set as output
• nSS is connected to RPi GPIO6, which is gpio97 on OPOS6UL set as output
• DIO0 is connected to RPi GPIO7, which is gpio10 on OPOS6UL set as input
• on recent models (like the one we tested) DIO1 is connected to RPi GPIO4, which is gpio18 on OPOS6UL set as input
• on recent models (like the one we tested) DIO1 is connected to RPi GPIO5, which is gpio19 on OPOS6UL set as input
• This Hat/Shield is using HOPERF RFM96W module (clone of Semtech's SX1276 ?) which is controlled through SPI bus.

# modprobe spidev

Testing that chip is recognized with python spidev

• Bring chip out of reset:

# echo 24 > /sys/class/gpio/export
# echo out > /sys/class/gpio/gpio24/direction
# echo 0 > /sys/class/gpio/gpio24/value
# echo 1 > /sys/class/gpio/gpio24/value

• activate it:

# echo 97 > /sys/class/gpio/export
# echo out > /sys/class/gpio/gpio97/direction
# echo 0 > /sys/class/gpio/gpio97/value

• read ID (register 0x42):

import spidev

spi = spidev.SpiDev()
spi.open(3,0)
to_send=[0x42,0x00]
spi.xfer(to_send)
[255, 255]

Tested Software

Gateway

• https://github.com/tftelkamp/single_chan_pkt_fwd
• To compile/install it:

Buildroot	Debian
$ make lora-forwarder	AsDevices library (0.18+) and git are needed. Board date/time should be correct to use git clone. Then: root@opos6ul:~# cd root@opos6ul:~# git clone https://github.com/tftelkamp/single_chan_pkt_fwd.git root@opos6ul:~# cd single_chan_pkt_fwd/ root@opos6ul:~/single_chan_pkt_fwd# make CFLAGS="-Wall -I/usr/include/as_devices/" LIBS="-las_devices"

• If not already loaded, load spidev driver:

root@opos6ul:~# modprobe spidev

• edit a script and put in it:

root@opos6ul:~# vim /root/start_gateway.sh

#!/bin/sh

echo 9 > /sys/class/gpio/export
echo 24 > /sys/class/gpio/export
echo 97 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio97/direction
echo out > /sys/class/gpio/gpio24/direction
echo in > /sys/class/gpio/gpio9/direction

/root/single_chan_pkt_fwd/single_chan_pkt_fwd

• Make it executable:

root@opos6ul:~# chmod a+x /root/start_gateway.sh

• Launch it ! ;-)

root@opos6ul:~# /root/start_gateway.sh

• To get & printout UDP data forwarded by the gateway (if -i runtime option is used):

#!/usr/bin/python

import socket
import json

UDP_IP = "192.168.1.28"	# my IP
UDP_PORT = 1700

sock = socket.socket(socket.AF_INET, # Internet
                     socket.SOCK_DGRAM) # UDP
sock.bind((UDP_IP, UDP_PORT))

while True:
	data, addr = sock.recvfrom(1024) # buffer size is 1024 bytes
	json_msg = data[12:]
#	print "received JSON message:", json_msg

	try:
		decoded = json.loads(json_msg)
#		print json.dumps(decoded, sort_keys=True, indent=4)
		if decoded.get('rxpk'):
			print "Packet data: ", decoded['rxpk'][0]['data']

	except (ValueError, KeyError, TypeError):
		print "JSON format error"

Node

• http://wiki.dragino.com/index.php?title=Use_Lora/GPS_HAT_%2B_RaspberryPi_to_set_up_a_Lora_Node

Buildroot

Debian

$ make lmic-pi

AsDevices library (0.18+) and unzip (apt-get install unzip) are needed. Then: root@opos6ul:~# cd root@opos6ul:~# wget https://github.com/ernstdevreede/lmic_pi/archive/master.zip root@opos6ul:~# unzip master.zip root@opos6ul:~# cd lmic_pi-master/lmic root@opos6ul:~# make CFLAGS="-c -Wall -I/usr/include/as_devices/" LIBS="-las_devices" root@opos6ul:~# cd ../examples/thethingsnetwork-send-v1/ root@opos6ul:~# make CFLAGS="-Wall -I/usr/include/as_devices/ -I../../lmic" LDFLAGS="-las_devices" root@opos6ul:~# chmod a+x thethingsnetwork-send-v1

# modprobe spidev
# echo 9 > /sys/class/gpio/export
# echo 18 > /sys/class/gpio/export
# echo 19 > /sys/class/gpio/export
# echo 24 > /sys/class/gpio/export
# echo 97 > /sys/class/gpio/export
# echo out > /sys/class/gpio/gpio97/direction 
# echo out > /sys/class/gpio/gpio24/direction 
# echo in > /sys/class/gpio/gpio9/direction
# echo in > /sys/class/gpio/gpio18/direction
# echo in > /sys/class/gpio/gpio19/direction

GPS

• GPS is connected to UART2 (/dev/ttymxc1)
• Use GPS to get time/date with NTP

Links

• http://www.dragino.com/products/module/item/106-lora-gps-hat.html
• http://wiki.dragino.com/index.php?title=Lora/GPS_HAT

LoRa is a registered trademark of Semtech.

RaspberryPi is a registered trademark of RaspberryPi Foundation.