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3.Firmware Updating | Instructions


Updating your preamp’s firmware requires the use of a bootloader program running on a PC together with the latest firmware “hex” file. You download both the bootloader and the firmware file from our website. Then you connect your PC to your preamp via a USB cable. To execute the actual upload process you run the bootloader program, apply power to your preamp and then use the bootloader to upload the firmware hex file into your preamp.

Once set up, the firmware upload/update process typically takes less than 15 seconds.

Detailed instructions on the firmware update process are provided herein.

What is the Bootloader?

The (mikro)Bootloader  is a small PC based software application that you use to establish USB communications with, and upload new firmware into, the V2/V25 preamp.

Unfortunately the Bootloader is a PC/Windows only application. There’s no MAC version currently available. We are not anti-MAC, but the supplier of our programming tools stubbornly refuses to provide a MAC version of the Bootloader program while providing no reasons for not doing so. Go figure.

The Bootloader program is a simple executable file (mikroBootloaderUSBHID.exe). Unlike conventional software, it does not have to be installed/registered into your PC. The program file simply has to reside somewhere on your PC. We suggest you download it to your PC desktop. The first time your run this program (by double clicking on it) it will create a small text file named “settings.ini” in the same directory. No special drivers are needed. It doesn’t install or change anything in your PC. If your PC has a USB port, you should be good to go.  We know the Bootloader works with Windows 7, 8 and 10. It may also work with  older versions of Windows but we haven’t tested that. To remove the Bootloader program from your PC simply erase both the  mikroBootloaderUSBHID.exe and settings.ini files from whatever directory you put them in.

Download The Bootloader


About USB Cables – Important!

The #1 problem that people encounter when trying to update their firmware is the inability to make a connection. In most cases this is caused by their USB cable.

Most of us have several USB cables laying around because we have cell/smartphones and other devices that use USB cables for charging. Unfortunately, many of those USB cables are for charging only and lack the ability to transmit data.

Charging only USB cables will not work with the bootloader and firmware update system!

You need to use a proper USB “data” cable that has the conductors for the D+ and D- USB data signals.

Firmware updating will not work without a proper USB data cable.

Firmware Update Procedure – Short Version

Here’s the short version of how this works.

  1. Preparation
    • Remove power from your preamp (unplug the power cord)
    • Download the updated firmware file from our website to your PC
    • Download the Bootloader program from our website to your PC
    • Connect your PC to the preamp via the USB cable provided with your preamp
  2. Start the Bootloader program
  3. Apply power to your Tortuga preamp (this starts a 5 second timer during which you must do the next step)
  4. Click the “Connect” button on the Bootloader program
  5. Browse for and select the firmware (hex) file you downloaded in step 1)
  6. Click on the “Begin Uploading” button on the Bootloader program.

With step 6) the actual uploading of the firmware takes less than 5 seconds. You’ll see a progress bar. It will be obvious when it’s done. When it’s done you can disconnect the USB cable from the preamp and proceed to use the preamp normally.

The information that follows below elaborates on the above steps.

Step 1 – Preparation

Remove Power From Your Preamp

This is key and often confuses people so read carefully. The Bootloader is only able to connect to your preamp during the 5 seconds after power is applied. If the connection hasn’t been made during that 5 second start-up period you have to remove power and try again. By “connection” we don’t mean physically connecting the USB cable. “Connection” means step 4.

Download Firmware File & Bootloader Program

The latest firmware file and the Bootloader program can both be found here [link to be added].

The firmware file is referred to as a “hex” file because it’s a text file wherein the code is formatted using a specific hexadecimal protocol and file uses a .hex file type suffix.

The Bootloader program is a small Windows executable (.exe) application file. You only need to download it once and keep it handy somewhere on your PC.

Connect The USB Cable

Finished Preamps

All finished Tortuga preamps require a USB cable with type A male connectors on both ends. The cable is supplied with all finished Tortuga Audio preamps. Connecting the cable does nothing by itself. Your PC should not react.

DIY Boards – Micro-B Socket

If you have an older V2 LDR3x DIY board with a micro-B socket board soldered to the J8 header on the board you’ll need a cable with a male A end and male micro-B USB end. An LED light on the micro USB connector breakout board on the V2 will light up once it’s connected to your PC.

DIY Board – Tortuga USB Connector

If you are using a Tortuga USB connector cable with the female end connected to the J8 header make sure you have the female end connected such that the red wire is next to microcontroller end of J8 header and not the end with the white dot.

Step 2 – Start the Bootloader program

When the Bootloader program starts it will look more or less like the pic below. At this point it won’t be doing anything except waiting.


Step 3 – Establish the USB link to the preamp

Connecting power to your preamp starts the 5 second bootloader connect window.

You should notice the following changes to the mikroBootloader program once power is applied to your preamp:

  1. The little USB symbol to the right of “1 Wait for USB link” should turn red
  2. The Device window should display “LR3x.V2 Board” or “LDR.V25” or similar
  3. The MCU Type window should display “PIC18” or “STM32F” or similar
  4. The History Window should say “Waiting MCU response…”

At this point you will have 5 seconds to establish a USB link between your PC and preamp by pressing the “Connect” button next to “2 Connect to MCU”. If all goes well, the “Connect” button text will change to “Disconnect” and the History Window will now say “Connected” as shown in the pic below. If you run out of time, don’t panic, just remove power again, wait a few seconds and then reapply power to the preamp which restarts the 5 second Bootloader timer.


Step 4 – Choose the firmware (.hex) file

Select your firmware file by pressing the “Browse for Hex” button next to “3 Choose HEX file”.  This will open a file dialog box. Find your downloaded .hex file stored on your PC and click the “Open” button. At this point the firmware is ready to be uploaded into the preamp board.


Step 5 – Upload Firmware To Preamp

Press the “Begin uploading” button next to “4 Start bootloader” to upload the firmware into the preamp. The previous firmware build will first be erased and then the updated software build will be written to the preamp’s microcontroller chip. This erase/write operation is very fast and should take less than 5 seconds to complete.

You should get a “Success” message. Click the  “OK” button to close the message box. Note the new messages in the History Window. Upon a successful write, the Bootloader program will automatically disconnect from preamp and the preamp will reboot which takes 5 seconds.

You are now done and can close the Bootloader program, disconnect the USB cable, and enjoy your updated preamp.


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