Article updated on March 8, 2021, to include the B-STLINK-ISOL board.
ST recently launched B-STLINK-ISOL, a module for the STLINK-V3SET that offers galvanic isolation and works with microcontrollers that draw less than 3.3 V. Engineers can use it in two different ways. When connected to the STDC14 connector of the STLINK-V3SET, the B-STLINK-ISOL fits into its white casing and serves as a traditional debugging probe. When connected between the STLINK-V3SET and its adapter board MB1440, the new model ensures that developers can access all signals and connectors on low-power MCUs. Hence, it offers similar features as the B-STLINK-VOLT with the added benefit of galvanic isolations. Such a feature provides isolation between the PC and the board. Indeed, when two circuits use the same ground, ground loops may cause damages or interferences. Galvanic isolation solves this issue by protecting against ground loops.
The B-STLINK-VOLT is an STLINK-V3 adapter board enabling the STLINK-V3SET in-circuit debugger/programmer probe to work with STM32 microcontrollers (MCU) that draw less than the traditional 3.3 V. Put simply, it’s a conversion circuit that lowers the voltage down to as little as 1.65 V; thus ensuring developers can use STLINK-V3 with systems that rely on a small battery, for instance. Users find the same STDC-14 connector to debug and program their MCU using JTAG, SWD, SWV, or VCP and it’s possible to communicate using SPI, UART, I2C, CAN, or GPIOs. We also updated our user manual to cover the various jumper configurations possible and the board’s installation into the STLINK-V3SET case.
The STLINK-V3SET popularized the use of extension cards that fit right into its housing to ensure engineers have a neat module with everything under one roof. Until now, teams using STM32 at 1.8 V relied on STLINK-V2. The reason was simply that STLINK-V3 focused on performance and a voltage reduction necessarily lowers the frequency of the various interfaces. Hence, when STLINK-V3 was just new, most engineers didn’t mind using the previous generation of probes since performance would have been the same anyway. However, as STLINK-V3 is now increasingly popular and customers crave the flexibility that comes with the adapter cards of the STLINK-V3SET, we decided to launch the B-STLINK-VOLT, and now the B-STLINK-ISOL, thus opening STLINK-V3 to a whole new range of STM32 applications. Please note that working with STM8 doesn’t require the new adapter board since it includes a voltage conversion circuit.
The Driving Forces: Versatility and Flexibility
The STLINK-V3 was a complete architectural overhaul when it came out a couple of years ago. It transfers data faster than the previous generation and with a lot more flexibility, thanks in part to its STDC-14 connector and its support of a virtual COM port. Besides the STLINK-V3SET, ST offers the STLINK-V3MINI, and STLINK-V3MODS, which don’t support adapter boards but offer a much smaller design for engineers looking primarily for portability. However, all three probes observe one principle: they must work regardless of unexpected edge cases or new applications. STLINK-V3 thus focuses on versatility thanks to a clever interface, a powerful connector, and the presence of various modules to tailor our offerings to more developers.
When Professor Zhu, of the University of Maine, presented a curriculum teaching embedded systems to undergraduates with our drone kit, educators asked about the ST’s debugging tools. The drone kit is too small to integrate the STLINK interface, thus requiring an external module. The audience’s response to the STLINK-V3’s features and probe selection was overwhelmingly positive. To better understand why the new B-STLINK-VOLT is a sign of the popularity of the STLINK-V3 series, let’s see five reasons behind the success of our latest in-circuit debugger/programmer.
1. STLINK-V3: A Strong Heritage
ST-LINK/V2, the previous generation remains highly popular and diverse. The first standalone device came out in 2011 and meant that developers could quickly and easily connect the in-circuit debugger/programmer between their board and their PC to compile their code, send their application to their MCU, benefit from unlimited breakpoints in RAM, and figure out if the system can run or if an error would cause problems. We know that the solution is highly popular amongst professionals and large engineering teams, which is why we will continue to sell and support our ST-LINK/V2 devices. We are deploying our new STLINK-V3SET, STLINK-V3MODS, and STLINK-V3MINI, but we also understand that some may want to continue to use something that’s familiar to them.
Furthermore, the family of ST-LINK/V2 products extends far beyond the standalone models as there are third-party variants with different form factors that remain quite popular. There’s also an ST-LINK/V2 directly integrated into our development solutions, like on the STM32 Discovery kits or Nucleo boards, which we optimized for the Serial Wire Debug (SWD) interface to ensure a small footprint. One of its features is the mass storage support that provides users the ability to open a storage volume on their PC to drag-and-drop binaries instead of going through an IDE to start uploading their application.
2. A Faster In-Circuit Debugger/Programmer
Data transfers are the bread and butter of this platform, which explains why the first significant architectural difference between the ST-LINK/V2 and STLINK-V3 is the latter’s compatibility with the USB 2.0 Hi-Speed interface. Previously, developers had to contend with a 12 Mbit/s USB 2.0 Full-Speed data rate, which could be cumbersome when uploading large applications. The latest modules now offer theoretical speeds of up to 480 Mbit/s, which will result in a drastically faster experience. Furthermore, beyond the simple interface upgrade, ST also implemented multiple optimizations of its algorithms and processes, making this a thorough architectural overhaul instead of a simple speed bump. Hence, the increase in productivity for teams that upload tremendous applications multiple times a day is highly noticeable.
Beyond better speed, the STLINK-V3SET, and STLINK-V3MINI, offer mass storage support to allow for a much more convenient upload process. Until now, only the ST-LINK/V2 present on some of our development boards, such as all our Nucleo boards, offered this feature. However, with the new models, engineers will be able to connect the in-circuit debugger/programmer, then drag and drop binaries to upload them in no time. This is particularly useful for developers wanting to quickly experiment with a demo application on a custom PCB, and who would rather not have to compile their code and send it through their IDE. It also makes swapping demos far more convenient, especially when teams are in the field.
3. A More Flexible Tool
The ST 14-pin debug, the STDC-14, present on the STLINK-V3SET, the B-STLINK-VOLT, and the STLINK-V3MINI is another reason for the modules’ flexibility. When users open their boxes, they will find the traditional MIPI 10-pin cable, which is relatively compact and very popular, and a new STDC 14-pin cable. The MIPI 10-pin version doesn’t support a virtual COM port. As a result, we developed an extension of the MIPI-10 connector that uses four additional pins to offer more features.
This is important because until now, engineers had to use extra cables and find workarounds to get a virtual COM port when they didn’t have the ST-LINK/V2 built into their development board. Thanks to the STDC-14, using a virtual COM port is a lot more practical. Similarly, the in-circuit debugger/programmer opens the door to an entirely new set of features as it allows PC developers to drive a couple of GPIOs from the new ST-LINK thanks to the DLL API present in STM32CubeProgrammer. As a result, teams can potentially add LEDs that light up as a sign that a routine performs its job, control other peripherals, or even use proprietary extensions via these IOs.
4. A Versatile Companion
The new architecture offers the same versatility as previous generations, with the possibility of using JTAG (Joint Test Action Group) and SWD for the STM32 MCUs. It also adds a tremendous level of flexibility with the possibility of using an STDC-14 connector to benefit from a virtual COM port. However, the STLINK-V3SET goes even one step further with the ability to add extension cards on the debugger/programmer to increase its functionalities.
Another example of our platform’s flexibility is the availability of a complementary interface board that allows developers to upload firmware through the SPI, I2C, or UART interface. This extension card serves as a bridge between the target board and the PC. Using the STM32CubeProgrammer software tool, either in a command line or graphical interface mode, developers can seamlessly use this bridge in their environment to facilitate maintenance operations without leaving a debug port open, which can represent a severe security breach.
Another example is Percepio and its Tracealyzer for the STLINK-V3SET. Tracealyzer is the premier trace visualization tool for developers of RTOS-based software systems, providing over 30 graphical views and live visualization. Tracealyzer v4.2 integrates support for STLINK-V3SET, allowing for a comprehensive insight into STM32 software during development, debugging, validation, and optimization.
5. A Custom Approach to Developers’ Needs
The STLINK-V3SET will attract developers with more extensive needs. The module comes with more cables as it is compatible with the larger and still useful MIPI-20 connector. It also has a height-adjustable casing that will adapt to the size of the stack present on top of the STLINK-V3SET so users can neatly house their extension cards. The STLINK-V3SET is also compatible with SWIM (Single Wire Interface Module) to ensure teams can program and debug an STM8.
As a result, it is much larger than the STLINK-V3MINI, which is so small that it can fit in the palm of a hand, making it a delight when developers must carry them while touring show floors or in the field. In many of these cases, developers lose the need for the SWIM interface or the port for extension cards, but the module’s size and weight become critical factors. Similarly, the STLINK-V3MODS is as small (15 x 30 mm) and engineers can directly solder it onto a PCB to vastly increase their prototype’s practicality. Hence, to have the ability to purchase a smaller, more cost-effective, and more pertinent system means scaling the STLINK-V3 architecture to better fit the wide range of engineers that use STM32 solutions.