Garmin High Speed Protocol or Network

Garmin Striker 5 dv

As a proud owner of this nice sonar I wonder how I could connect to the device using a raspberry. There is something called „Garmin High Speed Network“. There should be a way.

So first I opened the device and had a close look at the PCB. Nothing is indicating a special protocol, so my best guess is, it is standard UART.  I connected my Salea Logic analyser to the TX line of the Garmin Striker 5 dv and tried around with the settings. And I am right:

  • UART
  • Bit rate: 115200 8N1
  • Inverted is the key to get a proper communication.
  • LSB

After sending the signal through an inverter like a CMOD 4093, I have the data sent out by the device every 10 seconds:


My guess now is, that this is a „here I am“ message. When I replay this message back to the device, then I receive this message back:

0x10, 0x06, 0x02, 0x7B, 0x00, 0x7D, 0x10, 0x03

Looks like it starts with 0x10 and ends with 0x10, 0x03. It is an ACK.

Found something interesting: That is the missing link. Now I am building an Arduino App to talk to it. I will keep you updated.

Now I have a short sample ready and am understanding the documents. Searching for some detail returns a link to gpsbabel. So I will give it a try.

My research will go on!