ePot.V3 Mini & Max firmware updating

The document is undergoing heavy editing. It’s incomplete. The detailed firmware updating procedure is missing. 

Document application #

This document is only relevant to the ePot.V3 series of electronic stepped attenuator & preamp controller and related V3 preamps.

What is firmware? #

All of Tortuga Audio’s preamp’s  are controlled by a software driven microcontroller which is a type of embedded microprocessor widely used in commercial, industrial and consumer equipment. The software running on the microcontroller is referred to as “firmware”.

Firmware is a class of computer software that controls a specific hardware device and is typically stored in that devices’s read only memory. By its nature firmware is neither easy to erase nor is it easy to replace or update especially as compared to software applications that run on a personal computer. Firmware usually runs directly on a microcontroller’s “bare metal” without any intervening operating system.

Why update your firmware? #

The simple reality with software is there are always bugs that need fixing and new features and capabilities that keep getting added. Most  of the time the casual owner of equipment can ignore all that. But sometimes the bug is significant and once the fix is in the only way to get that fix into your machine is to do a firmware update.

Firmware versions & changelog #

Firmware for the ePot.V3 is common to both the Mini and the Max. That means there’s a unified common source code used for both the Mini and the Max. The firmware versions shown in the changelog below  reflect this commonality and applies to both the Mini and Max.

However, the Mini uses a 64 pin microcontroller while the Max uses a 100 pin microcontroller and each uses difference pins than the other. Moreover, certain functionality present in the Max is not present in the Mini. As a result, the firmware download files for the Mini and Max are NOT identical and are NOT interchangeable. You must download the Mini firmware file for the Mini and the Max firmware file for the Max. 

104 - 9.8.20** Initial release for Max **
* Changes (Max) - numerous revisions/changes under the hood that are relevant only to the Max
* Change - Revised internal system for storing setting data to eeprom
* Change - Removed encoder type menu item for both Max and Mini - wasn't relevant to the V3
* Change - Converted encoder decoding to simplified state machine logic - polling only - no interrupts

103 - 8.28.20* Change - Updated to software timer code to improve clarity and reliability
* New (Max) - Added automatic Cal start. User can adjust from 0 days (off) up to 365 days (1 year). Default is 30 days. Cal will only start automatically when unit is turned off.
102 - 8.26.20 * Change - Major revision of UART serial communications section in preparation for handling balanced systems (all under the hood stuff relevant only to the Max)
101 - 8.20.20* New - Added default input impedance to info display
* Fix - Display timeout period was not being stored properly
100 - 8.18.20* New - Initial release for ePot.V3 Mini

Which firmware version do you have? #

You must have an OLED display attached to your V3 in order to tell which firmware version you currently have. The firmware version is shown by selecting the “Version” menu. The firmware version is displayed as a 3 digit number as for example “FW: 108”

Firmware updating overview #

Before wading into the detailed firmware updating procedure described below it’s helpful to have an understanding of the overall process and tools required.

The process in brief is as follows:

  • Download the updated firmware file from our website to your computer
  • Connect your computer to the V3 with a USB/USB-serial cable
  • Start the programmer application on your computer, select USB connection, and select the firmware file you had already downloaded
  • Place your ePot.V3 into bootloader mode
  • Establish live connection between the programmer application and your V3
  • Execute the firmware download into your V3 by your programmer application
  • When the download is complete,  restart your V3 preamp and your done!

The bootloader #

In order to update the V3 firmware you need to place the V3 into “bootloader” mode. The bootloader is a specialized application that resides on the V3’s microcontroller whose sole purpose is to facilitate firmware updating. We did not create the bootloader application. It was loaded into the V3 microcontroller by the microcontroller manufacturer. You never have to worry about damaging or erasing the bootloader application. It resides in protected memory on the V3 controller chip.

You must start the bootloader application in order update the V3 firmware. There are 2 ways to start the bootloader program.

The first and easier way is to go to the V3 OLED display and scroll down the menu list to the “Firmware” menu item and select it. Follow the instructions on the display to start the bootloader. The display screen will probably go blank and the V3 will appear non-responsive. This is normal. It is now in bootloader mode waiting for a query from the programmer application running on your computer.

The second and more awkward way is to go to your Mini or Max board and find the S1 (Reset) and S2(Boot) push button switches on the board. First press/hold down the Boot push button and then while still holding down the Boot switch also press/release the Reset button and then release the Boot button. Nothing obvious will happen when the V3 enters bootloader mode. That’s normal and that’s OK. Read on.

The programmer #

The STM32CubeProgrammer, a.k.a. the “programmer”, is a powerful multipurpose microcontroller programming application that is made available for free by the manufacturer of the microcontroller used in the ePot.V3. It’s a multi-platform application meaning there’s a version that will run under Microsoft Windows, LINUX and the Apple MAC OS. You have to download this application and install it on your computer before proceeding with any firmware update. You only have to do this download/install once.

We use the programmer to communicate with the bootloader through a USB connection. During the firmware update process the programmer erases the existing firmware and then uploads a new version.

The USB cable #

A USB cable is required to connect your computer, that is running the programmer application, with the V3, that is running the bootloader application.

If you have one of our finished V3 preamps, then you only need a ______________ type cable with the typical male A plug on the computer end and a Mini B plug where the cable connects to the rear panel of the preamp.

If you have one of our DIY V3 Mini or Max boards things are a bit more complicated because the V3 does not accommodate a direct USB connection. Instead, the V3 has a serial data (UART) port that has RX (receiver) and TX (transmitter) pin connections. Fortunately, there are many specialized USB-to-Serial cables and also USB-to-Serial adapters available for typically $5-10 that take care of this USB-Serial conversion.

The firmware file #

The final piece of the puzzle is the updated firmware file itself that you are going to load into the V3. You download this file directly from our website as described in more detail below.






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