Can't make USB serial connection to OSEPP Uno R3

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Can't make USB serial connection to OSEPP Uno R3

Postby dshepherd » Sun Aug 05, 2018 9:53 pm

Can't make USB serial connection to OSEPP Uno R3
also posted in Courses / Python Programming and GUI's
ref: https://www.elektor.com/python-3-programming-and-guis

I've ran into a snag at Chapter 5 The Arduino Uno as a Slave
Specifically at Program 5-1 Use check buttons to select state of output
I'm unable to get prog_05_01.py "Write Digital Outputs" to toggle the 4 LEDs I have wired up to

digital output pins 2,3,4,5.
If I execute prog_05_01.py in a terminal , clicking write gives the output:
(repeats 5 times ex tries 0-4)
"Incorrect address or project number for slave, project = 1 address = 1
failed to connect"
I never see tx/rx leds on Uno blinking

I have:
.. loaded slave.hex correctly (no error in log,)
.. set up user pi as a member of dialup group
.. fitted 10uf electrolytic capacitor between reset and ground
.. set slave address = 1, project = 1

My hw/sw setup is:

#1 Raspberry Pi 3b v1.2 ~2015,
OS:Raspbian Linux raspberrypi 4.9.41v7+ #1023 SMP Tue Aug 8 16:00:15 BST 2017 armv1 GNU/Linux
utilities: python3-serial 3.2.1-1, avrdude 6.3.2+rpi1, python 3.5.3 , incl tkinter

#2 OSEPP Uno R3 Plus ~2016, ATmega328P, (note avrdude detects device signature 0x1e950f, probably

m328p )
https://www.osepp.com/electronic-module ... no-r3-plus
dshepherd
 
Posts: 6
Joined: Sun Aug 05, 2018 8:00 pm

Re: Can't make USB serial connection to OSEPP Uno R3

Postby dshepherd » Sun Nov 11, 2018 1:44 pm

Success! (Thanks for your troubleshooting advice Andrew Pratt!)

Root cause:
In my Raspberry Pi 3b environment the Arduino Uno USB connection is seen at /dev/tttyUSB0

To fix Rasp Pi Serial comm problems with prog_05_01.py, prog_05_02.py and others
USE THIS FOR Rasp Pi ...

Note: Don't type in the line numbers, they're for reference only: ex. 85-89

In
/home/pi/programs/chap05_progs
uno_slave.py

change line# 88 to

if fl[3:6] == 'USB':

ex.
class Uno
connect(Self)

85 acms = []
86 file_list = os.listdir('/dev')
87 for fl in file_list:
88 if fl[3:6] == 'USB':
89 acms.append(fl)
dshepherd

Posts: 5
Joined: Sun Aug 05, 2018 3:00 pm
dshepherd
 
Posts: 6
Joined: Sun Aug 05, 2018 8:00 pm


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