RTCM Client

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The Micro-Node RTCM and VOTER interfaces are typically used with AllStar in voting/simulcast applications. They MAY be used for ANY repeater interface application, through the chan/voter channel driver.

The VOTER is the original through-hole board designed by Jim Dixon for this application. It is open-source, and the relevant Gerber files and BoM to build it are available.

The Micro-Node Radio Thin Client Module (RTCM) is the commercial version of the VOTER. It uses surface mount parts (SMT), but is functionally equivalent to the original VOTER.

In general, the two terms (RTCM/VOTER) are used interchangeably, as they operate the same, and use the same firmware (mostly, see below).

This page will highlight some of the operational concerns, quirks, bugs, and other items of interest that relate to these interfaces. Much of the information has been gleaned off the AllStar mail list, comes from personal experience, or comes from notes in the firmware source code.


The firmware in the RTCM and VOTER is the same, except it is compiled for the specific dsPIC that is installed in each. As such, the firmware is specific to the VOTER or the RTCM, and is NOT interchangeable (it won't boot in the wrong device). Firmware for the RTCM is denoted by "smt" in the filename.

The VOTER uses a dsPIC33FJ128GP802 and the RTCM uses a dsPIC33FJ128GP804.

There are two parts to the firmware, a bootloader, and then the actual firmware file. The bootloader starts when power is applied, and allows you to talk to the dsPIC and load new firmware files over ethernet. If the bootloader is not intercepted by the loading tool, it will continue to boot the current firmware file.

All new boards will need to have the bootloader installed first, followed by a firmware file. You can load a firmware file directly (.hex) in to the dsPIC, but then you will not have any of the bootloader remote loading features.

The current bootloader (.cof file) is available here: https://github.com/AllStarLink/voter/tree/master/voter-bootloader (the -smt file is for the RTCM). It needs to be loaded with a PICKit programmer.

Current firmware (.cry file) is available here: https://github.com/AllStarLink/voter/tree/master/board-firmware . They are loaded with the EBLEX C30 Programmer.

There are multiple "flavors" of firmware available. See below for further explanation of what all the options mean.

The DSPBEW versions have Jim's DSP/BEW feature enabled. Note that due to the size of this feature, the diagnostics menu is NOT available in this version.

The CHUCK versions have Chuck Henderson's RSSI and Squelch modifications enabled. This is probably the version that most user's will want to use in production.

Compiling Environment

If you look in the votersystem.pdf, you will find a procedure to modify and load the bootloader in to the dsPIC of a VOTER board.

Unfortunately, there is an important step missing in that procedure, which is covered below.

In addition, the old links for the MPLAB software are dead, so let's update this info and get you going.

Currently (Feb 2017), you can get the required software from: http://www.microchip.com/development-tools/downloads-archive

Download MPLAB IDE 32-bit Windows v8.66: http://ww1.microchip.com/downloads/en/DeviceDoc/MPLAB_IDE_v8_66.zip http://dvswitch.org/files/AllStarLink/Voter/MPLAB_IDE_v8_66.zip

Download MPLAB C Compiler for PIC24 and dsPIC DSCs v3.31 NOT v.3.25: http://ww1.microchip.com/downloads/en/DeviceDoc/mplabc30-v3_31-windows-installer.exe http://dvswitch.org/files/AllStarLink/Voter/mplabc30-v3_31-windows-installer.exe

Optionally, install Windows Virtual PC and XP Mode. This is getting to be pretty old software, so running it under XP Mode may be a good idea, so we can keep it isolated (install it in a virtual machine). It does run fine in Windows 7.

Run the MPLAB IDE installer. You don't need to install the HI-TECH C Compiler at the end (click no).

Run the MPLAB C Compiler installer.

Select Legacy Directory Name.

Select Lite Compiler

Go to: https://github.com/AllStarLink

Follow the links to: voter --> Clone or Download --> Download Zip

That will get you voter-master.zip which is a download of the whole VOTER tree from GitHub.

Extract it somewhere (ie. in the XP Mode Virtual PC).

Launch the MPLAB IDE.

Go to Configure --> Settings --> Projects and de-select one-to-one project mode.


If you need to load the bootloader in to a fresh board, you will need to follow these steps.

Go to Project --> Open --> voter-bootloader.mcp --> Open (it is in the voter-bootloader folder of the GitHub source)

Go to File --> Import --> voter-bootloader --> ENC_C30.cof --> Open This step is missing from the original procedure.

Select View --> Program Memory (from the top menu bar).

If you want to change the default IP address from

Hit Control-F (to "find") and search for the digits "00A8C0".

These should be found at memory address "03018".

The "A8C0" at 03018 represents the hex digits C0 (192) and A8 (168) which are the first two octets of the IP address. The six digits to enter are 00 then the SECOND octet of the IP address in hex then the FIRST octet of the IP address in hex.

The "0B01" at 0301A represents the hex digits 0B (11) and 01 (1) which are the second two octets of the IP address. The six digits to enter are 00 then the FOURTH octet of the IP address in hex then the THIRD octet of the IP address in hex.

Otherwise, if you just want to load the bootloader...

Remove JP7 on the VOTER Board. This is necessary to allow programming by the PICKit2/PICKit3 device.

Attach the PICKIT2/PICKit3 device to J1 on the VOTER board. Note that Pin 1 is closest to the power supply modules (as indicated on the board).

If you have not already selected a programming device, go to Programmer --> Select Device and choose PICKit3 (or PICKit2, depending on what you are using).

Then go to Programmer --> Program. This will program the bootloder firmware into the PIC device on the board.


To compile the firmware (if you want to make custom changes)...

Go to Project --> Open --> navigate to board-firmware and open the .mcp file for the flavor of firmware you want to compile. They are in the board-firmware folder of the GitHub source.

NOTE: the .mcp files with the "smt" suffix are for the RTCM (built with SMT parts). The non-smt files are for the ORIGINAL through-hole VOTER boards. The difference is that the VOTER uses a dsPIC33FJ128GP802 and the RTCM uses a dsPIC33FJ128GP804.

Go to Project --> Build Configuration and select "Release". This may not be necessary (I don't believe that option is used in the firmware), but it removes the compiler option of __DEBUG being passed, so theoretically it would build "normal" firmware.

Go to Configure --> Select Device and choose the appropriate device for your board from the Device list. If you don't select the right one, the board will not boot. Select dsPIC33FJ128GP802 for the VOTER, and dsPIC33FJ128GP804 for the RTCM.

Now, if you go to Project --> Build All it should compile everything and show you "Build Succeeded".

A .cry file should be in the board-firmware folder. You can load this with the ENC Loader.

There is also a .hex file in there that you could load with a programmer... but that would wipe the bootloader... so don't do that.

Chuck Squelch

If you want to enable "Chuck Squelch", open the HardwareProfile.h and un-comment #define CHUCK.

You may also want to go down to Line 291 in Voter.c (right click on the window, go to Properties --> "C" File Types --> Line Numbers) and tack on CHUCK after 1.60 (the current version number) so that when you load this firmware, the version will be shown as 1.51CHUCK, and you'll know that Chuck Squelch is compiled in. We should probably make that more automagic in the future...


If you want to compile the DSPBEW version, open the DSPBEW project file instead.

GPS Issues

NMEA Sentences

If you are using an NMEA GPS (as opposed to a Trimble using the TSIP binary interface), the RTCM/VOTER is looking for the following NMEA sentences:


Trimble Thunderbolt

Garmin LVC