RE: shell over NUS (NUS shell transport) not working as expected

frankbuss — Thu, 30 Nov 2023 14:46:58 GMT

I had the same problem. For Linux, there are tools from Nordic to solve it, see the documentation: developer.nordicsemi.com/.../shell_bt_nus.html

But I wrote a simple one file Python script to have just a terminal to the NUS shell. It is a bit slow, because of the polling, but otherwise works well, including ANSI color, tab-completion etc.:

#!/usr/bin/env python3

# installation requirement:
# pip3 install bluepy
#
# first connect a USB bluetooth adapter. "hcitool dev" should show it:
#
# $ hcitool dev
# Devices:
#         hci0    18:4F:32:F2:16:22
#
# If not, then check, if the USB device is recognized at all:
#
# $ lsusb
# Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
# Bus 001 Device 019: ID 0a5c:21e8 Broadcom Corp. BCM20702A0 Bluetooth 4.0
# ...
#
# If it doesn't get detected, try another USB adapter.
#
# If detected, then maybe first start it:
#
# sudo hciconfig hci0 up
#
# Sometimes the Bluetooth stack gets stuck, and even a `hcitool lescan`
# doesn't work anymore, or you get an error like this:
# bluepy.btle.BTLEManagementError: Failed to execute management command 'scanend' (code: 11, error: Rejected)
# In this case, restart the interface like this:
#
# sudo hciconfig hci0 down
# sudo hciconfig hci0 up
#
# If you have more than one USB bluetooth adapter, try hci1 etc.
#
# Then start the peripheral, and search for the key fob:
#
# $ sudo hcitool lescan
# LE Scan ...
# E9:56:3D:BF:59:3E FOOBAR
# ...
#
# Important: if you have more than one bluetooth adapter, then old Bluetooth 4 adapter
# might see it, too, but it won't work with it. Then as described above, use the right
# adapter with hciconfig.
# 
# Finally start the NUS script:
#
# $ ./nus.py E9:56:3D:BF:59:3E
#
# the output should look like this:
# connected
#
# Then you can use it like a terminal, tab-completion works, too.

import struct
from bluepy.btle import *
import sys
import time
import atexit

import sys, termios
from select import select

if len(sys.argv) != 2:
	print("usage: python nus.py bluetooth-address")
	exit()

# save the terminal settings
fd = sys.stdin.fileno()
new_term = termios.tcgetattr(fd)
old_term = termios.tcgetattr(fd)

# new terminal setting unbuffered
new_term[3] = (new_term[3] & ~termios.ICANON & ~termios.ECHO)
termios.tcsetattr(fd, termios.TCSAFLUSH, new_term)

def getch():
    return sys.stdin.read(1)

def kbhit():
    dr,dw,de = select([sys.stdin], [], [], 0)
    return len(dr)>0

# at script exit, restore termios settings
def restore():
    termios.tcsetattr(fd, termios.TCSAFLUSH, old_term)
    print()
atexit.register(restore)

# callback class for handling Mobee messages
class MyDelegate(DefaultDelegate):
    def __init__(self):
        DefaultDelegate.__init__(self)

    def handleNotification(self, cHandle, data):
        sys.stdout.buffer.write(data)
        sys.stdout.flush()

# connect to device
per = Peripheral(sys.argv[1], "random")
print("connected")

while True:
    try:
        # set callback for notifications
        per.setDelegate(MyDelegate())

        # enable notification
        setup_data = b"\x01\x00"
        notify = per.getCharacteristics(uuid='6e400003-b5a3-f393-e0a9-e50e24dcca9e')[0]
        notify_handle = notify.getHandle() + 1
        per.writeCharacteristic(notify_handle, setup_data, withResponse=True)
        
        # get send characteristics
        c = per.getCharacteristics(uuid='6e400002-b5a3-f393-e0a9-e50e24dcca9e')[0]
        
        # wait for answer
        while True:
            if per.waitForNotifications(0.0001) or True:
                if kbhit():
                    ch = getch()
                    c.write(ch.encode('latin-1'))
                continue
    except KeyboardInterrupt:
        sys.exit(0)
    finally:
        per.disconnect()

RE: shell over NUS (NUS shell transport) not working as expected

Geir Strand — Wed, 28 Jun 2023 19:47:56 GMT

Sometimes the simplest thing is creating problem. Problem lies (partially) between keyboard and chair:
I used the nRF Toolbox on the phone to try out the code.
Every time I tried to transmit something I saw that it got transmitted, and I got the characters echoed back. But nothing happened.
The problem is that when you send something from the nRF Toolbox (at least on iOS), the carrier-return/line-feed is not sent! This I discovered when debugging and seeing that only 4 characters got sent when it wrote "help" and hit return.
Making a macro did change all this.
An idea for the application team at Nordic: Make the serial terminal support Bluetooth LE serial port. There are cross-platform libraries for bluetooth (I don't know if it exists for electra, but python and others have now cross-platform libraries).

RE: shell over NUS (NUS shell transport) not working as expected

Einarh — Fri, 16 Jun 2023 13:37:11 GMT

Hello

Does the NUS shell example by itself work as intended?

If so, have you looked at the configs used in that sample?

Best regards,

Einar