Published March 15, 2016 © CC BY

UDOO Neo Wifi Scanner

Check wifi signal strength and available networks using external antenna on UDOO Neo.

IntermediateWork in progress1 hour2,265

Things used in this project

Hardware components

Adafruit SSD1306 OLED

Wifi Antenna 9dBi

Wifi Antenna 7dBi

Wifi Antenna 5dBi

UDOO NEO

Hand tools and fabrication machines

Soldering iron (generic)

Story

I want to have wifi in my shed. This proved to be a difficult proposition since an all galvanized steel enclosure with a concrete base is pretty impervious to 2.5GHz and 5GHz radio waves.

I was planning to deploy a UDOO Neo in the shed so I decided to test various antenna and record signal strengths. With antennas bigger is usually better. So I had 3 sizes under test - 5, 7 and 9 dBi dipoles. I also hooked up a small OLED containing Arduino shield which I got a part of my attempts to monitor energy usage. I will eventually use the energy monitor in conjunction with solar panels.

1 / 2 • UFL + Capacitor External Antenna Mod

The first step in testing external antennas is to switch over the capacitor on the UDOO Neo board which feeds the signal from the PCB antenna to the traces that connect to the external U.FL. connector. As well as solder on the said U.FL. connector. My SMD soldering skills came in handy and I got some help from the UDOO guys over twitter and the mod took only 10 minutes.

1 / 2 • Antenna Showdown

The 9dBi performed best at signal levels around -78 dBm from the main router within the house, channeled via an external repeater.

UDOO installed in the shed, Solar charge controller to be replaced

The final signal to the install in the shed is shown below:

udooer@tishneo:~$ iw dev wlan0 link
Connected to 00:e0:20:41:ba:3c (on wlan0)
      SSID: bowireless
      freq: 2437
      RX: 596935 bytes (4068 packets)
      TX: 261071 bytes (2021 packets)
      signal: -71 dBm
      tx bitrate: 19.5 MBit/s MCS 2
      bss flags:      short-slot-time
      dtim period:    3
      beacon int:     100

Code

Python wifi scanner with OLED display for UDOO NEO

#!/usr/bin/env python

# Ported from:
# https://github.com/adafruit/Adafruit_Python_SSD1306/blob/master/examples/shapes.py
# Also includes wifi scanning

from oled.device import ssd1306, sh1106
from oled.render import canvas
from PIL import ImageFont
import commands
import re

font = ImageFont.load_default()
device = ssd1306(port=1, address=0x3C)


if __name__=="__main__":
    scan_result = commands.getoutput("sudo /sbin/iw dev wlan0 scan")
    ssids = [x.group(0)[6:] for x in re.finditer("SSID:.*\n",scan_result)]
    signals = [x.group(0).lstrip("signal: ").rstrip(" dBm\n") for x in re.finditer("signal:.*\n",scan_result)]
    print ssids,signals
    with canvas(device) as draw:
        # Load default font.
        font = ImageFont.load_default()

        # Alternatively load a TTF font.
        # Some other nice fonts to try: http://www.dafont.com/bitmap.php
        # font = ImageFont.truetype('Minecraftia.ttf', 8)

        # Write all SSID's in brief
        y = 0
        for ssid,signal in zip(ssids,signals):
            draw.text((0, y), ssid[:10],  font=font, fill=255)
            draw.text((84, y), signal, font=font, fill=255)
            y += 10

Credits

Tisham Dhar

13 projects • 59 followers

I am an Electronics Engineer who mostly works with aerial and space based remote sensing projects. I fiddle with home automation and renewable energy projects.

UDOO Neo Wifi Scanner

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

Schematics

UDOO Neo with OLED display shield

Code

Python wifi scanner with OLED display for UDOO NEO

Credits

Tisham Dhar

Comments

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UDOO Neo Wifi Scanner

UDOO Neo Wifi Scanner

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

Schematics

UDOO Neo with OLED display shield

Code

Python wifi scanner with OLED display for UDOO NEO

Credits

Tisham Dhar

Comments

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