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Reverse Engineering The Midland WR120-EZ

Attempting to re-band the radio into the ham band as well as develop a tool for backup and restore via serial using the built-in clone port.

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Midland NOAA Weather Alert radio. Listens on 1 of 7 frequencies for S.A.M.E. encoded messages to trigger hazard alerts for your area. Plans to re-band it into the ham band as well as develop backup and restore software.

The Details:

I bought this radio some time ago for weather alerts but no longer use it. It is on the chopping block and I've got a few plans for this little guy.

The Goals:

  • Create an application to backup and restore the radio using the in-built cloning port
  • Probe the port and see if I can talk to it for the purpose of dumping firmware
  • Reprogram radio to support out of band ham frequencies to allow me to create a simple inexpensive radio for SKYWARN and ARES alerts... or you know, just fun shit like sending messages to a group. (radio uses SAME encoding which is well documented)
  • Attempt dump and flashing of internal memory, possibly installing a teensy to allow flashing on demand and possible firmware modifications.

  • 1 × UART Serial UART to communicate with radio
  • 1 × Oscilloscope Probing test points
  • 1 × Bus Pirate Dumping the Winbond chip
  • 1 × 3.5mm Breakout Leads Accessing the serial port

  • Talking Back to That Port

    Signals Everywhere/KR0SIV07/20/2017 at 05:58 1 comment

    Time to talk to the serial port!

    After listen to what the serial port had to save I've put together enough to figure out what I need to say to the radio to get it to start entering LOAD mode.

    Sending the hex bytes 0xEE get things started.

    Serial port capture

    Python code snip

    The radio does enter LOAD mode


    A little problem

    After successfully writing commands to enter LOAD mode (the first step to software based restoration of settings) I found that when I have the UART attached to the RX pin on the radio it no longer just spits out data but rather waits for me to send another command back, I'll have to do some more digging.

    When the UART is connected to the radio's RX pin it doesn't like to talk as much.

    Next Time?

    The next update with any luck should be an opensource application to backup and restore these radios. Once I manage to decode the data (likely by making small setting changes or dumping the winbond chip I should be able to allow modification of saved settings from a computer, allowing you to program these alert radios without having punch everything in by hand.

  • Determining Clone/Serial Port Baudrate

    Signals Everywhere/KR0SIV07/20/2017 at 03:37 0 comments

    She speaks serial! Let's hook it up to a UART.

    Once I have the radio hooked up to a UART I attempt several times to capture data, unable to find the correct baudrate.

    RealTerm - Guessing BaudrateHaving a hard time guessing the baudrate

    Alright maybe there is a better way....

    I found this website online and it worked out quite nicely.. https://www.kumari.net/index.php/random/37-determing-unknown-baud-rate

    Baudrate / Oscilloscope Chart
    Using my Oscilloscope I was able to measure the shortest burst as suggested in the above link/website. This gave me a reading of about 800.0us in width which should round out to about 1200 baud.

    Does she look good now?

    Serial DumpCaptain, we haz data!


    Data obtained from clone

    [17/07/2017 19:26:00] Read data (COM4) 
        ee 07 90 03 85 90 03 35 90 03 55 90 03 55 91 03   î..….5.U.U‘. 
        aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa   ªªªªªªªªªªªªªªªª 
        aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa   ªªªªªªªªªªªªªªªª 
        aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa   ªªªªªªªªªªªªªªªª 
        aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa   ªªªªªªªªªªªªªªªª 
        aa aa aa aa aa aa aa aa aa aa aa 2d 2d 2d 2d 2d   ªªªªªªªªªªª----- 
        2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 00 2d 2d 2d 2d 2d   ----------.----- 
        2d 2d 2d 2d 2d 2d 00 2d 2d 2d 2d 2d 2d 2d 2d 2d   ------.--------- 
        2d 2d 00 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 00 2d   --.-----------.- 
        2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 00 2d 2d 2d 2d 2d   ----------.----- 
        2d 2d 2d 2d 2d 2d 00 67 f9 71 ff 3b fe f0 03 00   ------.gùqÿ;þð.. 
        02 02 02 02 02 02 ff ff 00 03 26 06 00 07 b2 b1   ......ÿÿ..&...²± 
        ff c0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ÿÀÿÿÿÿÿÿÿÿÿÿÿÿÿÿ 
        ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ 
        ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff   ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ 
        ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 64   ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿd 
        5a                                                Z                
    [17/07/2017 19:26:04] Read data (COM4) 
        05                                     

    Alright! We're not off to a bad start.

    Stay tuned for more.

  • Cloning Port/Confirmed Serial

    Signals Everywhere/KR0SIV07/20/2017 at 03:24 0 comments

    Hello cloning port, what language do you speak?

    First thing is first, what language does the port speak and can I talk to it without too much trouble.


    Let's Probe It!

    The voltage of the port is actually about 3v, I was using the wrong attenuation when the screenshot was taken. I'm assuming serial communications at this point.


    Let's Sniff it!

    I don't expect any data on this port unless I'm trying to clone the radio, to do this remove the batteries and power the radio up via the cable while holding the  < and  > buttons. This should give you the following screen.

    To Unit / Clone ModePress < > at the same time during boot, press select when ready to send.

    I used a 3.5mm break out cable and a UART to intercept communications while peering in with my oscilloscope.


    Scope Capture, oh yeah I think we've got serial!

    As I expected when the radio is powered we get a steady 3v on the tx pin and when I hit select to start the cloning process we see data as a square wave where the port is being pulled down to near 0v and and going back high to send data.

  • Header Installation/Findings

    Signals Everywhere/KR0SIV07/20/2017 at 02:43 0 comments

    I installed a header onto what I had high hopes to be a 14 pin JTAG header, it turns out these pins actually go to each button and LED on the radio. So nothing super useful to me there. Just bridge a pin to ground and it'll trigger whatever button or LED.

  • What's Inside/No FCC ID?

    Signals Everywhere/KR0SIV07/20/2017 at 02:38 0 comments

    Normally when working on any electronics project the first thing I do is grab the FCC ID. Something everything with some type of radio will have and nearly any electronic device as well. A company like Midland not having such an ID struck me as odd.

    Nevertheless I started tearing into it and seeing what there was to this odd little radio.

    Here is what I found

    Masked CPU

    Masked CPUSeveral Test Points but no other indications

    Unknown Chip With Test pads

    Unknown chipTest pads check voltage, no indication of data

    Finally, something I can play with. A Winbond flash memory chip.

    Winbond 25x40bvnig 8SOIC ChipWinbond 25x40bvnig 8SOIC Chip : Click for datasheet

    A UTC petw chip used as an audio amplifier for the Alerts

    UTC ChipUTC MC34119L: Click for datasheet

    Possible JTAG Header

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