python uart

[thivtulz]

here this my coding..

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import serial
usbport = '/dev/ttyAMA0'
ser = serial.Serial(usbport, 9600, timeout=1)
ser.write("Raspberry pi\r\n")
ser.timeout = 2
print ("write data = Raspberry pi")
time.sleep(2)

while True:
           response=ser.read()
           time.sleep=2
           print (" read data: python \n")
           print (response)
  
ser.close()

i can't read data from my PC.Please help me..

[scotty101]

What is the output when you run the python file?

ser.read() will only return 1 byte of data.

[thivtulz]

the output is

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write data:Rasperry pi
read data: 
read data:

its continue looping.I can write something in my PC but can't receive data or input from PC.please help me.Don't know how to do.

[scotty101]

Can you explain how you have connected the two devices together?

[thivtulz]

i connect RPi to the PC using UART cable.That cable connect with the USB port.Then i use YAT terminal in my PC to send data from RPi by running the python code.But the problem is i can't receive data from PC.Please help me ..

[-rst-]

Does your PC receive the string "Raspberry pi" (output from RPi with the ser.write(), if I understand the setup correctly)?

[thivtulz]

yes my PC can receive Raspberry pi but couldn't send from PC.

[-rst-]

Ok, that's promising - at least the connection seems ok ...of course there may be an issue with the RX line on the RPI side...

There's at least one clear issue in your code:

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time.sleep=2

inside the while loop should most likely read:

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time.sleep(2)

The sleep before the while loop seems unnecessary. Also not sure if the line ser.timeout should be there (as the timeout is already set in the ser init).

[thivtulz]

Still i can't receive data from PC.Is there any other coding to receive data from PC.help me.How python can communicate with UART.

[DMcK]

Using the code below, I can send and receive from the Pi in Raspbian and xbian. I can't get it to receive using raspbmc:

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import time
import serial
ser = serial.Serial(port='/dev/ttyAMA0', baudrate=38400, timeout=1)
ser.write("\x02**INP\x03")
time.sleep(0.05)
result=ser.read(ser.inWaiting())
if "INPS04" in result:
 ser.write("\x02**INPS05\x03")
else:
 ser.write("\x02**INPS04\x03")
ser.close()

So, it may be the distribution you are using causing issues (like raspbmc for me), or you could try reading the data on the port with "result=ser.read(ser.inWaiting())"

[thivtulz]

same problem can't receive from PC.I send data from RPi to PC(windows) can receive but reverse can't. RPi can't receive data from PC(windows)

[thivtulz]

After i run this code the YAT terminal(PC) ask me to login..
Lyk tis..

<LF>raspberry login:
<LF>password:

if i login also i can't run the code.Help me please..

[thefatmoop]

Bit late to the party but for those stuck on this:
in a terminal:
$sudo raspi-config

go to advanced options -> enable/disable shell and kernel messages on serial connection -> disable it.

$sudo reboot

Now nothing is hogging up /dev/ttyAMA0.