What Is the Main Difference Between the STM32F407VET6 and the F407VGT6 in the Same Package?
When engineers compare the STM32F407VET6 and the STM32F407VGT6, the question usually comes from a practical place: a board designed for one part is available, but only the other is in stock, or a project is outgrowing its current memory and a drop-in upgrade is needed. Both parts are LQFP100 devices from STMicroelectronics' STM32F407 line, both run at 168 MHz, and both carry the same ARM Cortex-M4F core with a floating-point unit and DSP instructions. The difference that matters is not architectural. It is almost entirely a matter of Flash density.
Decoding the Part Numbers
ST's part-numbering scheme makes the distinction explicit once the code is broken down. In the STM32F407VET6 and STM32F407VGT6, the "V" indicates the LQFP100 package, the "T6" indicates the industrial temperature range of −40°C to +85°C, and the single letter before "T6" encodes the Flash capacity. "E" stands for 512 KB of embedded Flash, while "G" stands for 1 MB. Everything else in the ordering code refers to the same package, temperature grade, and product family. This is why the two parts share a pinout and why one can replace the other on an existing PCB without layout changes.
What Stays Identical
The shared specification list is long and covers essentially every functional block in the microcontroller. Both variants provide 192 KB of SRAM, including 64 KB of core-coupled memory (CCM) that is tightly coupled to the Cortex-M4F core for deterministic, low-latency data access. Both expose 82 general-purpose I/O pins on the LQFP100 package. Both include three 12-bit ADCs with 16 external channels, two 12-bit DACs, 14 timers (including two advanced-control PWM timers for motor drive), a 10/100 Ethernet MAC, USB OTG FS and HS, two CAN controllers, FSMC for external memory or parallel displays, and a DCMI camera interface. The supply range is 1.8 V to 3.6 V on both, and the operating temperature range is identical. In practical terms, if a design uses the Ethernet MAC, the USB OTG port, the FSMC bus, or the motor-control timers, that design will behave the same on either part.
The Specification That Changes
The Flash memory capacity is the only meaningful difference. The VET6 provides 512 KB, while the VGT6 provides 1024 KB (1 MB). This matters because Flash determines the maximum size of the compiled firmware image, including application code, middleware, an RTOS, communication stacks, and any lookup tables or font data stored in program memory. A project that links comfortably within 512 KB will run identically on both devices. A project whose binary exceeds 512 KB will fail to link on the VET6 and will require the VGT6, or a different memory strategy such as external Flash via FSMC, which adds cost and board complexity.
Comparison Table
| Parameter | STM32F407VET6 | STM32F407VGT6 |
|---|---|---|
| Core | ARM Cortex-M4F with FPU and DSP | Identical |
| Max frequency | 168 MHz (210 DMIPS) | Identical |
| Flash memory | 512 KB | 1024 KB (1 MB) |
| SRAM | 192 KB (incl. 64 KB CCM) + 4 KB backup | Identical |
| Package | LQFP100 (14 × 14 mm) | Identical |
| GPIO | 82 I/Os | Identical |
| ADC / DAC | 3 × 12-bit ADC, 2 × 12-bit DAC | Identical |
| Ethernet / USB | 10/100 MAC, USB OTG FS+HS | Identical |
| Timers | 14 (incl. 2 advanced-control PWM) | Identical |
| Pinout | LQFP100 standard | Identical (drop-in) |
| Relative cost | Lower | Higher |
Practical Implications for Selection
The decision rule is straightforward. Start with the VET6 if there is no evidence that the firmware will exceed 512 KB. In many production designs, the compiled binary with an RTOS, a USB stack, and application logic sits well under 400 KB, leaving headroom. The VET6 is the more economical choice and uses the same board design. Move to the VGT6 when the linker reports a Flash overflow, when a known middleware stack such as a full TLS library or a large communication protocol is expected to push the image past the 512 KB boundary, or when future feature growth is anticipated and a re-spin is undesirable. Because the VGT6 is a drop-in replacement with the same pinout and peripherals, it can also serve as a production fallback when VET6 supply is constrained.
Questions and Answers
Q: Can the VGT6 directly replace the VET6 on an existing PCB without any hardware or software changes?
A: Yes, for hardware. The pinout, package, and peripheral set are identical. Firmware compiled for the VET6 will run on the VGT6 without modification. The reverse is not always true: firmware that exceeds 512 KB will fit on the VGT6 but not on the VET6. The only consideration is that the Flash size reported to the debugger or bootloader differs, but this is handled by the toolchain and does not require application changes.
Q: Does the larger Flash on the VGT6 affect SRAM size or SRAM partitioning?
A: No. Both devices provide 192 KB of SRAM, including 64 KB of CCM, plus 4 KB of backup SRAM. The SRAM layout and address map are the same. The Flash size difference does not change the amount of RAM available for stack, heap, or data buffers.
Q: Is there any difference in peripherals, clock speed, or analog performance?
A: No. The core, maximum frequency, ADC resolution and channel count, DAC, timers, communication interfaces, and Ethernet MAC are identical. The VET6 and VGT6 are the same microcontroller with different amounts of embedded Flash. Any difference observed in a design would come from board-level factors or from firmware that does not fit in 512 KB, not from a peripheral or analog discrepancy.
Q: Why would a project choose the VET6 if the VGT6 is a drop-in upgrade?
A: Cost. The VET6 is typically less expensive per unit. If the firmware fits within 512 KB and there is no credible near-term requirement to exceed that limit, paying for 1 MB of Flash that will never be used is unnecessary. The VET6 is the rational default for cost-sensitive, space-constrained designs that have confirmed their memory budget.
Conclusion
The STM32F407VET6 and STM32F407VGT6 are not two different microcontrollers in the LQFP100 package. They are the same microcontroller with two Flash density options. The VET6 offers 512 KB and the VGT6 offers 1 MB, while every other functional parameter — core, clock, SRAM, peripherals, pinout, and temperature range — remains identical. Selection therefore reduces to a single engineering question: does the firmware fit in 512 KB? If yes, the VET6 is the economical choice. If no, or if future growth is likely, the VGT6 provides the headroom without requiring a board redesign.
