I'm sending an integer from python using pySerial.
import serial
ser = serial.Serial('/dev/cu.usbmodem1421', 9600);
ser.write(b'5');
When i compile,the receiver LED on arduino blinks.However I want to cross check if the integer is received by arduino. I cannot use Serial.println() because the port is busy. I cannot run serial monitor first on arduino and then run the python script because the port is busy. How can i achieve this?
You could listen for the Arduino's reply with some additional code.
import serial
ser = serial.Serial('/dev/cu.usbmodem1421', 9600); # timeout after a second
while ser.isOpen():
try:
ser.write(b'5');
while not ser.inWaiting(): # wait till something's received
pass
print(str(ser.read(), encoding='ascii')) #decode and print
except KeyboardInterrupt: # close the port with ctrl+c
ser.close()
Use Serial.print() to print what the Arduino receives to the serial port, where your Python code is also listening.
You can upload an arduino program that listens for that specific integer and only blinks the light if it gets that int.
Related
I am trying to get an LED to respond to a python program (using python 3.8), and it is not receiving anything. When I connect to the port, the led blinks to indicate it is connected, but then does nothing. Here is my code:
import serial
ser=serial.Serial('/dev/cu.usbmodem1411', 2000000, timeout=1)
ser.write(b'H')
time.sleep(200)
while True:
#read echo back from arduino verify receipt of message
#will show printing of x from arduino program
data = ser.readline()[:-2]
if data:
print (data.decode())
The while loop doesn't print out anything, and I also tried using the Arduino interface and it send signals fine, so my wiring is correct, but there is something missing with the python code. Has anyone run into this before?
The problem seems to be due to the wrong band speed you are using for the serial port. ser=serial.Serial('/dev/cu.usbmodem1411', 2000000, timeout=1) The value 2000000 here can never be true. There is no such value. The default is 9600, but I'll share a photo showing you the band speed on the Arduino side, the band speeds here and there should be equal.
I have chosen the following setup to read sensor data by Arduino and an XBee-connection:
List itemA TMP36-sensor is connected to an Arduino Uno
List itemA Sparkfun XBee-shield with an XBee S2C is mounted on the Arduino (Router, API-mode). The Arduino is connected to COM3.
List itemCOM4 is connected with a Sparkfun XBee-Explorer (USB-connection). Another XBee S2C is connected on the explorer. This XBee is the coordinator (API-mode).
I have written the code for reading data from Xbee-Explorer at COM4:
#! /usr/bin/python
# Import and init an XBee device
from xbee import XBee, ZigBee
import serial
ser = serial.Serial('COM4', 9600)
xbee = XBee(ser)
while True:
try:
enter response = xbee.wait_read_frame()
print response
except KeyboardInterrupt:
break
ser.close()
At the moment it is not possible to get any data received by the Xbee with the Python code, although it is possible to read the data by XCTU.
In Detail:
If I send sensor data (sensor reading and sending to Xbee is done by Arduino Software) from the router to the coordinator, I'm able to read the data frames by XCTU and the results make sense. If I use the Python-code above, I did not get any data frames, although the RSSI-diodes of router and coordinator are blinking independently from the software (XCTU or Python) I use.
For me it is not clear what is going wrong and I would be happy to get some help to solve the problem.
Thank you very much for your support.
Regards Daniel
I had the same problem, changing from API=2 to API=1 solved my problem
I try to make communication between my device and python code via COM4 a communication port: pyserial communication.
So at first I try to send and write a hello then to read the output of my device,
But the problem for me is how to read the hello that is sent firstly. I mean that I want to read the string hello on COM4 from my device
import serial
ser = serial.Serial(
port='COM4',\
baudrate= 230400) # open serial port
print(ser.name) # check which port was really used
#ser.write(b'hello\n') # write a string
#str=ser.readline()
while True:
print(ser.read(30).decode())
ser.close() # close ports
The code of my device is written in C language.
I would be very grateful if you could guide me please.
This process differs based on the operating system. Here's a good library that supports Linux and Windows:
http://www.teuniz.net/RS-232/
I am trying to interface with my com ports, specifically an XBee connected to thi using this code.
from xbee import XBee
from serial import Serial
PORT = 'COM3'
BAUD = 9600
ser = Serial(PORT, BAUD)
xbee = XBee(ser)
# Send the string 'Hello World' to the module with MY set to 1
xbee.tx(dest_addr='\x00\x01', data='Hello World')
# Wait for and get the response
print(xbee.wait_read_frame())
ser.close()
However, this error keeps arising.
SerialException: could not open port 'COM3': WindowsError(5, 'Access is denied.'). It goes away when I restart my computer, buts it keeps returning. I'd prefer to understand why its happening so I don't need to keep restarting my computer. Would really appreciate any help, thanks. I am working through the IDLE interface with python 2.7 just in case that is relevant.
A serial port can be "open" in only one application at a time. Once application "A" opens the port, application "B" will get an Access Denied error when it tries to open the same port. In your case, you need to figure out what other application is holding the port and close it first.
I have 2 programs to test serial communication, an simple arduino program that echoes whatever is on the serial port and a python program that writes to the serial port and prints the reply.
I'm having an issue where whenever I upload the arduino program and try to run the python the first time after I uploaded, it would be stuck on print ser.readline() which I'm assuming means for some reason python is not writing to the serial port. I would have to quit the python program and run it again to get it to get a reply from arduino. The program would continue to work until I re-upload the arduino then once again python wouldn't work on first run. Also if I open and close the serial monitor before I run the python program it will work the first run. Does anyone know what is the issue? This is on Ubuntu.
arduino
String str;
void setup() {
// Turn the Serial Protocol ON
Serial.begin(115200);
}
void loop() {
if (Serial.available()) {
str = Serial.readStringUntil('\n'); // Read the serial input
Serial.println(str); // sends ascii code
}
}
Python
import serial
ser = serial.Serial('/dev/ttyACM1', 115200)
for i in range(0,4):
str = "test string\n"
ser.write(str)
print ser.readline()
The issue is likely related to many Arduinos resetting when a new serial connection is made.
The solution is to either add a delay (about 2 seconds works) to the python program between the serial connection being created and the first data being sent or modifying the hardware to prevent a reset on serial connect.
By default python Serial might be blocking by default try removing the timeout:
ser = serial.Serial('/dev/ttyACM1', 115200,timeout=0)
additionally have a peek at the serial.threaded in the docs
I added
time.sleep(1)
ser.setDTR(level=0)
time.sleep(1)
after opening the serial port and the issue was fixed.