Friday, August 14, 2015

Another Yaesu VX-8DR external GPS with an Arduino/ATmega328 translator.

I've collected links for a few of these projects to add a better external GPS to the Yaesu VX-8DR, instead of the somewhat proprietary Yaesu option.

Here's another one from VK3YY that got posted recently:

Here's code from DFannin on github:
Update 2016-01-15, 4Z7DTF notified me about his project, which includes more additional analysis of how poor the VX-8's parsing and error handling is.

Background Info:

Good detailed blog post Reverse Engineering the Yaesu VX-8DR GPS Interface. From Feb. 2013. He didn't arrive at the solution, which I believe F4FXL and at least one other have. But I think he's got most of the relevant details for the padding differences listed as well as some other very useful info including details on the GPS chips used in VX-8 and VX-8G.

We now know how to connect to and send a properly formatted GPS NMEA message to the Yaesu VX-8DR. Here's the summary:
  • 9600baud TTL 3.3V serial signalling, 8/N/1
    • NOT RS232 -5 to +5V signalling -- you need a level converter if that's all you have
  • 3-wire physical interface to the following pins:
    Pin GPS Side Purpose Yaesu Side Purpose
    4 GPS RX Yaesu TX
    5 GPS TX Yaesu RX
    6 GPS GND Yaesu GND
  • According to 4Z7DTF (2016-01-15), there is no need for the communication to be bidirectional. Only the TX Data from the GPS to the VX-8 is required.

The messages need to be formatted exactly as follows:

Message Type Source Sentence
$GPGGA Sample $GPGGA,123223.000,4131.2334,N,00021.1216,E,1,04,02.7,00123.4,M,0051.7,M,000.0,0000*41

Syntax $GPGGA,hhmmss.sss,llll.llll,a,yyyyy.yyyy,a,x,xx,xx.x,xxxxx.x,M,xxxx.x,M,xxx.x,xxxx*hh
$GPRMC Sample $GPRMC,123223.000,A,4131.2334,N,00021.1216,E,0000.00,291.33,301011,,*3E

Syntax $GPRMC,hhmmss.sss,A,llll.llll,a,yyyyy.yyyy,a,xxxx.xx,xxx.xx,xxxxxx,,*hh
$GPZDA Sample $GPZDA,123223.000,30,10,2011,,*55

Syntax $GPZDA,hhmmss.sss,xx,xx,xxxx,,*hh

Thursday, August 6, 2015

rtl_433 now decodes DSC 433 Mhz wireless securty contacts

** UPDATE For status bit decoding see rtl_433 DSC Status Bit Decoding **

If you have a DSC (Digital Security Controls) home security system, with wireless sensors such as door / window contacts, glass break detectors, smoke, CO2, heat, and water detectors, you can now monitor them with rtl_433. The code is now in the mainline Merbanan github repo.

Only the 433 Mhz security sensors/contacts devices are currently supported.  I will be working on other devices soon. I have almost all of the status bits worked out. I will be submitting a pull request soon.

DSC alarm systems are also sold under other brands such as ADT Pulse, and a number of cable/telephone company's home automation systems, such as Time Warner Intelligent Home. DSC is a division of Tyco, so you will also see DSC products listed as Tyco Security, though Tyco has a whole list of security brands.

These are fairly inexpensive wireless devices that can also be useful for a variety of home automation projects.

The DSC WS4945 - Wireless Door and Window contact can be used as a magnetic contact or used with any sort of sensor that provides a normally closed output. If you are using it for home automation without a security system, it doesn't matter if it is normally closed or normally open. It will transmit at any state change. The device also sends a heartbeat with the current state every 64 minutes.

The Vanishing door/window contact, EV-DW4975 is quite thin and small if you don't need the screw terminals for wiring up some other type of sensor. It will barely be noticed on most doors and windows.

If you are interested in decoding DSC's wireless protocols, or have any information to share, please contact me, I could certainly use someone to collaborate with.

** UPDATE For status bit decoding see rtl_433 DSC Status Bit Decoding **

Popular Electronics Magazine archive online 1954 - 2003

A piece of electronics history:

Popular Electronics Magazine issues from 1954-2003 are available on line.  

Might be old news, but I just saw this circulating on a few mailing lists.

This is the first time I recall seeing a reference to this web site, American Radio History.

Popular Electronics was created in 1954 by Ziff-Davis Publishing for an audience of electronics hobbyists and experimenters. It soon became the "World's Largest-Selling Electronics Magazine". The circulation was 240,000 by 1957 and exceeded 400,000 by 1963. Rival Electronics World was merged into Popular Electronics in 1972.

Popular Electronics became Computers & Electronics in November 1982; and then ceased publication in April of 1985.

The title returned in February 1989 under the ownership of Gernsback Publications which purchased the name and gave it to their Hands-On Electronics magazine. Popular Electronics ceased publication in December of 1999, returning as Poptronics in January of 2000 after merging with Electronics Now. The final issue was  January, 2003.