As a part of my project I am using XBee. I want sample Python code to make two XBees to communicate with each other in Windows. I have written code, but it has a problem.
What would like to sent a message like "hello" from one XBee, and it should be printed on the other XBee side. How can I do this?
Take a look at the great python-xbee library, and Digi's examples.digi.com as two excellent resources for someone new to the XBee. Between those two sites, you should be able to get your XBee radios joined to each other (using the second link) and then get them working in Python (with the first link).
Before doing anything else you have to configure the devices, use XCTU software:
First device - Coordinator API mode:
- ID 7777(or any random value)
- DL set to FFFF
Second device - Router AT mode:
- ID 7777(has to be the same for every device)
- DL set to 0
Code for coordinator (listen mode):
import serial
import time
from xbee import ZigBee
PORT = "COM1" #change the port if you are not using Windows to whatever port you are using
BAUD_RATE = 9600
ser = serial.Serial(PORT, BAUD_RATE)
# Create API object
xbee = ZigBee(ser)
# Continuously read and print packets
while True:
try:
response = xbee.wait_read_frame()
print("\nPacket received at %s : %s" %(time.time(), response))
except KeyboardInterrupt:
ser.close()
break
Code for the remote device:
import serial
PORT = "COM1" #change the port if you are not using Windows to whatever port you are using
BAUD_RATE = 9600
ser = serial.Serial(PORT, BAUD_RATE)
while True:
try:
data = raw_input("Send:")
ser.write(data) #if you are using python 3 replace data with data.encode()
except KeyboardInterrupt:
ser.close()
break
Run the code and send data from the remote device to the coordinator. You will be able to see the packets printed in the console and in the rx_data field will be the payload.
I hope this is helpful.
Related
I am using Pjsip library to register a Sip account to Sip server
/* Register to SIP server by creating SIP account. */
{
pjsua_acc_config cfg;
pjsua_acc_config_default(&cfg);
cfg.id = pj_str("sip:" SIP_USER "#" SIP_DOMAIN);
cfg.reg_uri = pj_str("sip:" SIP_DOMAIN);
cfg.cred_count = 1;
cfg.cred_info[0].realm = pj_str(SIP_DOMAIN);
cfg.cred_info[0].scheme = pj_str("digest");
cfg.cred_info[0].username = pj_str(SIP_USER);
cfg.cred_info[0].data_type = PJSIP_CRED_DATA_PLAIN_PASSWD;
cfg.cred_info[0].data = pj_str(SIP_PASSWD);
status = pjsua_acc_add(&cfg, PJ_TRUE, &acc_id);
if (status != PJ_SUCCESS) error_exit("Error adding account", status);
}
This working fine when my board only has one network interface, but when i run it on a new board which has many network interface, it always register to Server via interface have smalless IP address value. I read in this link: https://trac.pjsip.org/repos/wiki/FAQ#multihomed And realize that Pjsip always chooses a network interface to register by its algorithm. And i tried to bind my application to a newtork interface too like this: https://unix.stackexchange.com/questions/210982/bind-unix-program-to-specific-network-interface but it not work too. I need to choose network interface manually in the code, how can i do it ?
Search for parameters named bound_addr in pjsip configuration - there should be (unless something changed with updates) one in transport configuration and one in rtp configuration. This is binding by interface address, not interface name, but it might be a starting point for modifications if necessary.
Any chance I could get a tip for proper way to build an agent that could do read multiple points from multiple devices on a BACnet system? I am viewing the actuator agent code trying learn how to make the proper rpc call.
So going through the agent development procedure with the agent creation wizard.
In the init I have this just hard coded at the moment:
def __init__(self, **kwargs):
super(Setteroccvav, self).__init__(**kwargs)
_log.debug("vip_identity: " + self.core.identity)
self.default_config = {}
self.agent_id = "dr_event_setpoint_adj_agent"
self.topic = "slipstream_internal/slipstream_hq/"
self.jci_zonetemp_string = "/ZN-T"
So the BACnet system in the building has JCI VAV boxes all with the same zone temperature sensor point self.jci_zonetemp_string and self.topic is how I pulled them into volttron/config store through BACnet discovery processes.
In my actuate point function (copied from CSV driver example) am I at all close for how to make the rpc call named reads using the get_multiple_points? Hoping to scrape the zone temperature sensor readings on BACnet device ID's 6,7,8,9,10 which are all the same VAV box controller with the same points/BAS program running.
def actuate_point(self):
"""
Request that the Actuator set a point on the CSV device
"""
# Create a start and end timestep to serve as the times we reserve to communicate with the CSV Device
_now = get_aware_utc_now()
str_now = format_timestamp(_now)
_end = _now + td(seconds=10)
str_end = format_timestamp(_end)
# Wrap the timestamps and device topic (used by the Actuator to identify the device) into an actuator request
schedule_request = [[self.ahu_topic, str_now, str_end]]
# Use a remote procedure call to ask the actuator to schedule us some time on the device
result = self.vip.rpc.call(
'platform.actuator', 'request_new_schedule', self.agent_id, 'my_test', 'HIGH', schedule_request).get(
timeout=4)
_log.info(f'*** [INFO] *** - SCHEDULED TIME ON ACTUATOR From "actuate_point" method sucess')
reads = publish_agent.vip.rpc.call(
'platform.actuator',
'get_multiple_points',
self.agent_id,
[(('self.topic'+'6', self.jci_zonetemp_string)),
(('self.topic'+'7', self.jci_zonetemp_string)),
(('self.topic'+'8', self.jci_zonetemp_string)),
(('self.topic'+'9', self.jci_zonetemp_string)),
(('self.topic'+'10', self.jci_zonetemp_string))]).get(timeout=10)
Any tips before I break something on the live system greatly appreciated :)
The basic form of an RPC call to the actuator is as follows:
# use the agent's VIP connection to make an RPC call to the actuator agent
result = self.vip.rpc.call('platform.actuator', <RPC exported function>, <args>).get(timeout=<seconds>)
Because we're working with devices, we need to know which devices we're interested in, and what their topics are. We also need to know which points on the devices that we're interested in.
device_map = {
'device1': '201201',
'device2': '201202',
'device3': '201203',
'device4': '201204',
}
building_topic = 'campus/building'
all_device_points = ['point1', 'point2', 'point3']
Getting points with the actuator requires a list of point topics, or device/point topic pairs.
# we only need one of the following:
point topics = []
for device in device_map.values():
for point in all_device_points:
point_topics.append('/'.join([building_topic, device, point]))
device_point_pairs = []
for device in device_map.values():
for point in all_device_points:
device_point_pairs.append(('/'.join([building_topic, device]),point,))
Now we send our RPC request to the actuator:
# can use instead device_point_pairs
point_results = self.vip.rpc.call('platform.actuator', 'get_multiple_points', point_topics).get(timeout=3)
maybe it's just my interpretation of your question, but it seems a little open-ended - so I shall respond in a similar vein - general (& I'll try to keep it short).
First, you need the list of info for targeting each device in-turn; i.e. it might consist of just a IP(v4) address (for the physical device) & the (logical) device's BOIN (BACnet Object Instance Number) - or if the request is been routed/forwarded on by/via a BACnet router/BACnet gateway then maybe also the DNET # & the DADR too.
Then you probably want - for each device/one at a time, to retrieve the first/0-element value of the device's Object-List property - in order to get the number of objects it contains, to allow you to know how many objects are available (including the logical device/device-type object) - that you need to retrieve from it/iterate over; NOTE: in the real world, as much as it's common for the device-type object to be the first one in the list, there's no guarantee it will always be the case.
As much as the BACnet standard started allowing for the retrieval of the Property-List (property) from each & every object, most equipment don't as-yet support it, so you might need your own idea of what properties (/at least the ones of interest to you) that each different object-type supports; probably at the very-very least know which ones/object-types support the Present-Value property & which ones don't.
One ideal would be to have the following mocked facets - as fakes for testing purposes instead of testing against a live/important device (- or at least consider testing against a noddy BACnet enabled Raspberry PI or the harware-based like):
a mock for your BACnet service
a mock for the BACnet communication stack
a mock for your device as a whole (- if you can't write your own one, then maybe even start with the YABE 'Room Control Simulator' as a starting point)
Hope this helps (in some way).
I try to run an example script from dronekit. the code is looks like this :
import gps
import socket
import time
from droneapi.lib import VehicleMode, Location
def followme():
"""
followme - A DroneAPI example
This is a somewhat more 'meaty' example on how to use the DroneAPI. It uses the
python gps package to read positions from the GPS attached to your laptop an
every two seconds it sends a new goto command to the vehicle.
To use this example:
* Run mavproxy.py with the correct options to connect to your vehicle
* module load api
* api start <path-to-follow_me.py>
When you want to stop follow-me, either change vehicle modes from your RC
transmitter or type "api stop".
"""
try:
# First get an instance of the API endpoint (the connect via web case will be similar)
api = local_connect()
# Now get our vehicle (we assume the user is trying to control the first vehicle attached to the GCS)
v = api.get_vehicles()[0]
# Don't let the user try to fly while the board is still booting
if v.mode.name == "INITIALISING":
print "Vehicle still booting, try again later"
return
cmds = v.commands
is_guided = False # Have we sent at least one destination point?
# Use the python gps package to access the laptop GPS
gpsd = gps.gps(mode=gps.WATCH_ENABLE)
while not api.exit:
# This is necessary to read the GPS state from the laptop
gpsd.next()
if is_guided and v.mode.name != "GUIDED":
print "User has changed flight modes - aborting follow-me"
break
# Once we have a valid location (see gpsd documentation) we can start moving our vehicle around
if (gpsd.valid & gps.LATLON_SET) != 0:
altitude = 30 # in meters
dest = Location(gpsd.fix.latitude, gpsd.fix.longitude, altitude, is_relative=True)
print "Going to: %s" % dest
# A better implementation would only send new waypoints if the position had changed significantly
cmds.goto(dest)
is_guided = True
v.flush()
# Send a new target every two seconds
# For a complete implementation of follow me you'd want adjust this delay
time.sleep(2)
except socket.error:
print "Error: gpsd service does not seem to be running, plug in USB GPS or run run-fake-gps.sh"
followme()
I try to run it in my Raspberry with Raspbian OS, but i got an error message like this :
Error : gpsd service does not seem to be running, plug in USB GPS or run run-fake-gps.sh
I get a feeling that my raspberry is needed a gps kind of device to be attached before i can run this script, but i dont really know.
Please kindly tell me whats wrong with it..
the full path of instruction i got from here :
http://python.dronekit.io/1.5.0/examples/follow_me.html
As the example says:
[This example] will use a USB GPS attached to your laptop to have the vehicle follow you as you walk around a field.
Without a GPS device, the code doesn't know where you are so it would not be possible to implement any sort of "following" behavior. Before running the example, you would need to:
Acquire some sort of GPS device (I use one of these, but there are lots of alternatives).
Configure gpsd on your laptop to interface with the GPS device.
I'm new to C and for a homework exam I must implement a simple server socket program which sends some data in a loop and if the client is connected to the server socket(have done it with Arduino but need the same functionallity on raspberrypi or other sbc).
For example (arduino style):
EthernetServer server = EthernetServer(23);
// start listening for clients
server.begin();
int i = 0;
while(true){
i++;
EthernetClient client = server.available();
if (client) {
while (client.connected()) {
if (client.available()) {
client.print(i);
}
}
}
client.stop;
}
I have a SBC (single board computer) with GPIO buss. My program must:
read values from SPI bus (infinite loop)
if the client is connected to the server scoket It must send some values to the client.
I know how to implement this kind of app in Java but in C, I don't have enaugh knowledge.
I'am looking for some kind of library or example on how to implement it.
regards
You can refer below mentioned link to establish a client/server connection using sockets with RPi with C implementation. Hope it helps you.
http://cs.smith.edu/dftwiki/index.php/Tutorial:_Client/Server_on_the_Raspberry_Pi
I have several embedded machines listening and streaming rtp audio data to a multicast group. They are connected to a smart managed switch (Netgear GS108Ev2) which does basic igmp snooping and multicast filtering on its ports, so that the rest of my (W)LAN doesn't get flooded.
At start everything works fine for about 500-520 seconds. After that, they don't receive any more data until they leave and join the group again. I guess the switch is "forgetting" about the join after a timeout.
Is there any way to refresh the group membership, i.e. letting the switch know, that there ist still someone listening, without losing packets?
System info:
Arch: blackfin
# cat /proc/version
Linux version 2.6.28.10-ADI-2009R1-uCBF54x-EMM
(gcc version 4.3.3 (ADI) ) #158 PREEMPT Tue Jun 5 20:05:42 CEST 2012
This is the way multicast / the IGMP protocol works. A client has to join the group periodically by sending a Membership Report or it will be assumed that he has left the group after some short timeout. However, those reports are usually sent only when receiving a Membership Query from the local multicast router. Either your clients don't receive the query or don't respond with a report.
Try to use a tool like wireshark in order to see which IGMP packets are sent through your network.
You need an IGMP querier to send the Membership Queries, as was already explained by scai.
If you can't configure your router to do that, you can use one of your computers. Seeing how running a full multicast routing daemon would be overkill (and I've never done that), I suggest you try to abuse igmpproxy.
First create a dummy upstream interface (this is not persistent!):
ip tap add dev tap6 mode tap
Write igmpproxy.conf:
# Dummy upstream interface.
phyint tap6 upstream ratelimit 0 threshold 1
# Local interface.
phyint eth0 downstream ratelimit 0 threshold 1
# Explicitly disable any other interfaces (yes, it sucks).
phyint NAME disabled
...
Finally start igmpproxy (as root):
igmpproxy -v /path/to/igmpproxy.conf
If your embedded devices are running linux, you need to turn off the reverse packet filter on them or they won't respond to group membership queries. In that case the upstream switch will assume there is no-one listening to that multicast and switch it off.
I had same problem, multicast on wifi was lost after 260 seconds, I solved it with my application by adding AddSourceMembership on socket.
private void StartListner(IPAddress sourceIp, IPAddress multicastGroupIp, IPAddress localIp, int port)
{
try
{
Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPEndPoint localEndpoint = new IPEndPoint(localIp, port);
socket.Bind(localEndpoint);
byte[] membershipAddresses = new byte[12]; // 3 IPs * 4 bytes (IPv4)
Buffer.BlockCopy(multicastGroupIp.GetAddressBytes(), 0, membershipAddresses, 0, 4);
Buffer.BlockCopy(sourceIp.GetAddressBytes(), 0, membershipAddresses, 4, 4);
Buffer.BlockCopy(localIp.GetAddressBytes(), 0, membershipAddresses, 8, 4);
socket.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.AddSourceMembership, membershipAddresses);
try
{
byte[] b = new byte[1024 * 2];
int length = socket.Receive(b);
}
catch { }
}
catch (Exception ex)
{
logger.Error("Exception: " + ex);
}
}