CODEWITHSUNDEEP
pythonserial-portarduinopyserial
birgit
birgit

Reputation: 1129

PySerial communication with variables

I am trying to interface with my Arduino via Pyserial on OS X. I am controlling LEDs with sending numbers from 0 to 9. The code as in 

import serial
arduino = serial.Serial('/dev/tty.usbserial', 9600)

arduino.write('5')

works perfectly fine, but I am trying to have the 5 in this example as a changeable variable but something like

arduino.write('%d') % 5

won't work. I don't know how to format a variable that the output is equal to the working example?

Upvotes: 1

Views: 5297

Answers (2)

msvalkon
msvalkon

Reputation: 12077

The string formatting must go inside the parentheses of the function call.

e.g. arduino.write("%d" % 5)

Here's some information on old-style string formatting

Upvotes: 2

jadkik94
jadkik94

Reputation: 7078

You were not formatting the string %d but the function call:

arduino.write('%d' % 5)

The % sign should go after the ' immediately.

This will work, but it is also preferable to use tuples with format strings:

arduino.write('%d' % (5,))

Because when you have multiple parameters, you will anyway have to use it this way:

arduino.write('%d.%d' % (2, 3))

Upvotes: 5

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