Sunday, June 3, 2018

MMDVM JumboSPOT board: Mods you may need

This is the JumboSPOT board that was/is sold on ebay and other online places. This board along with a Rasberry Pi Zero and a SD card loaded with PiStar makes up a Digital Radio Hotspot.

Depending on when you purchased your board and for what price, you may need certain modifications. The following mods have ONLY be tested / verified on the above board. As with anything in life, you take on the risk and responsibilities of preforming these mods. If you don't know what you are doing, STOP and don't do it!

Antenna mod

If you installed the SMA connector at P3 and plan to use the included SMA external Antenna you need to remove the cap ( see A in above picture ). This removes the connection to the internal ceramic Antenna ( not shown about ) at AE1. Bottom line is that you should not run two Antenna's so removing C28 makes sure that only Antenna is P3.

Flash FW mod

Most early boards shipped with only the 10 pin connector soldered as in the above picture. This meant that you were unable to flash updates to the STM32A103 microcontroller chip. Thus the two pins in the above picture ( marked B and in the red rectangle ) need to be connected to the Rasberry Pi's GPIO pins 20 and 21 which will be right below them.
It is a direct pass through, NOT a jumper as most people assume. So you just need to add a female header to your JumboSPOT board and a male header to the Raspberry Pi. Current boards place a 10 pin female header on both sides of the JumboSpot, which will work, but only thoes two pins are needed. Once the pins are connected you will be able to use the PiStar Firmware update script to update your JumboSpot to the latest version of HS_HAT which is displayed on the PiStar admin page.

OLED display mod

If you just purchased the JumboSPOT board it most likely did not come with an OLED display. You can add one later on if you like. Just look for " 0.96" I2C IIC SPI Serial 128X64 White OLED LCD LED Display Module for ArduinoG9K " or similar. The display gets connect to the top row in the above picture ( refrence "C" ) and not the bottom row that is marked. The main issue is that the pins must match the board pins which are listed above. From left to right they are [3.3v] [GND] [SCL] [SDA] So since you solder the display so that it's facing out the screen you purchase should match that config like so:
 I was able to find this module for 450% less then the ones listed as compatible to the JumbSPOT so don't get fooled by the seller, you can use compatible modules as long as it has the correct pins and supports "I2C IIC SPI Serial". Also note that the display will NOT turn on unless you have it configured and PiStar attaches to a server on the Internet ( as in Brandmister etc ). In PiStar http://pi-star.local/admin/configure.php make sure you have it configured as in:

Adding Ethernet to your Pi Zero mod

This one requires no-soldering! Just chose the correct part from eBay or your favorite Chinese vendor. The PiStar distribution will support an Ethernet adapter out of the box. It's even smart enough to use Ethernet over WiFi and fall back to WiFi if Ethernet fails. But which one to get. If you search for "MMDVM Hotspot Ethernet Adapter" you will be paying the most you can pay. If you look for "Micro USB 2.0 to Ethernet 10/100 RJ45 Network LAN Adapter" you will find ones EIGHT TIMES less! Make sure that it supports Linux and you will be safe. Also I suggest getting one more then you need. When I ordered three, only two worked. Since I only needed two it was worth buying extra ( these parts are really REALLY cheap and cheaply made ).

What do you think?

Please leave constructive comments. If you have mods of your own please share. Like most of you out there I was attracted to this hobby because I could MOD things, make them better! So pitch in and share your knowledge!


  1. As reminder to whom ever reads this, the JumboSpot DOES NOT need the Ethernet adapter since it has built in Wi-Fi, but hard wiring ethernet is more stable over time. You only need the adapter if you want to physically connect it to your home network if you plan to run the JumboSpot full time.

    1. Er.. The JumboSpot board itself has no wifi, that's on the Pi Zero W board.

  2. Thanks for the tips - de ka2ugz


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