V25 firmware updating instructions

 Application #

The information in this document applies to both the V2 and V25 versions of Tortuga Audio’s preamp controllers.

Procedure overview #

Updating your preamp’s firmware requires the use of a bootloader program running on a PC together with the latest firmware “hex” file. You can download both the bootloader application and the firmware file from our website.

To execute the actual upload process you:

  • Unplug your preamp from its power source
  • Start the bootloader application program on your PC
  • Then plug in the USB cable from your PC into the preamp
  • Depending on the version of your V25 hardware you might also have to plug power into your preamp.
  • At this point you have a 5 second window to connect the bootloader app to the preamp (details on this below)
  • Once connected, you select the firmware hex file you previously downloaded and stored on your PC, and upload it into your preamp. The actual upload proper takes less then 5 seconds.

The rest of this document elaborates on the firmware updating process described above.

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.

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 here #


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.

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 1 – Preparation #

Download the bootloader application #

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

Download the firmware file #

Please refer to other sections within the V25 firmware topic for downloading the firmware file itself. Store the file on your PC somewhere where you can easily find it.

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.

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.

Connect your USB cable to your PC but NOT to the preamp #

Please not this carefully. DO NOT CONNECT YOUR USB CABLE TO YOUR PREAMP YET!! But please do connect one end to your PC.

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 #

This is perhaps the trickiest and most confusing part of the process. All V2 boards and earlier Rev A versions of V25 boards require that power be plugged into the preamp to initiate the 5 second bootloader connection window. Later version B & C of the V25 board can be powered directly from their USB connection. Hence the following procedure differs slightly depending on the hardware model/version you have.

  1. Apply power to your preamp
    1. V2 & V25-RevA preamps
      1. Connect USB cable to the V25
      2. Connect power to the V25
    2. V25-RevB/C preamps
      1. Only connect USB cable to the V25 (not power)
  2. The little USB symbol to the right of “1 Wait for USB link” should turn red
  3. The Device window should display “LR3x.V2 Board” or “LDR.V25” or similar
  4. The MCU Type window should display “PIC18” or “STM32F” or similar
  5. 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.

bootloader_2 #

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.

bootloader_3 #

Step 5 – Upload the firmware to your 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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