STM32H7 Series — Cortex-M7 at 480 MHz with DMA2D and LTDC

The STM32H7 is STMicroelectronics's highest-performance MCU family, with Cortex-M7 cores at up to 480 MHz, hardware double-precision FPU, 1 MB+ on-chip SRAM, and a full DMA2D (Chrom-ART) engine plus LTDC display controller. It is the most capable STM32 target for rich GUI applications demanding smooth 60 fps animation on panels up to WVGA (800×480) resolution.

Sparklet on STM32H7 delivers:

• DMA2D-accelerated widget blit, fill, and alpha blend — CPU stays focused on application logic.
• LTDC double-buffer configuration for tear-free display with hardware vsync sync.
• On-chip SRAM framebuffer placement — no external SDRAM required for 480×272 and 800×480 configurations.
• External SDRAM framebuffer support for WVGA and higher resolutions via FMC interface.
• Hardware JPEG decode peripheral (on STM32H7Bx variants) for compressed background image loading.

The STM32H7 is commonly used for industrial HMI control panels, medical device interfaces, building automation controllers, and automotive body HMI where the RH850 or i.MX 8 are over-specified. It is the most common STM32 variant evaluated by teams migrating from TouchGFX — see Sparklet vs TouchGFX for a detailed comparison.

STM32F4 Series — Cortex-M4 Workhorse with DMA2D and LTDC

The STM32F4 series is the most widely deployed STM32 family in industrial, consumer, and medical embedded systems. Cortex-M4 at 168–180 MHz, on-chip SRAM up to 256 KB, DMA2D (on STM32F4x9 variants), and LTDC for RGB panel driving. The STM32F429 and F469 are the most common GUI-capable F4 parts.

Sparklet on STM32F4 provides:

• DMA2D integration on F4x9 variants — hardware fill, memory-to-memory blit, and pixel format conversion.
• Software renderer fallback for lower F4 variants without DMA2D — Sparklet's optimised C renderer delivers usable frame rates at 320×240 to 480×272 on 168 MHz cores.
• SDRAM framebuffer configuration via FMC for larger display resolutions.
• Minimal RAM footprint from 16 KB — suited to STM32F4 parts with 128–192 KB on-chip SRAM.

The STM32F4 is particularly cost-effective for medical device displays, industrial HMI panels, and consumer electronics where a mid-range Cortex-M4 is the right balance of performance and BOM cost. FreeRTOS and Azure RTOS (ThreadX) integrations are documented for STM32F4 targets.

STM32U5 Series — Cortex-M33 with Low-Power GUI for IoT and Wearables

The STM32U5 is STMicroelectronics's ultra-low-power MCU family, combining a Cortex-M33 at 160 MHz with TrustZone security, advanced power management (run mode down to 19 µA/MHz), and hardware graphics acceleration on select variants. Designed for battery-powered IoT devices, wearables, and portable medical instruments that require a display without sacrificing battery life.

Sparklet on STM32U5 leverages:

• Partial rendering (dirty-region update) — Sparklet only redraws changed screen regions, dramatically reducing active display time and DMA2D usage — key for maximising battery life on coin-cell or small Li-Po powered devices.
• Low-power display blanking API — Sparklet exposes display sleep/wake APIs that coordinate with STM32U5 stop modes for near-zero idle power consumption.
• TrustZone-compatible codebase — Pure C with no dynamic allocation — compatible with STM32U5 TrustZone secure/non-secure memory partitioning in medical and IoT security contexts.

The STM32U5 is Sparklet's recommended target for wearable display GUI applications on STM32 silicon, and for portable medical instruments requiring IEC 62304 software lifecycle documentation. See low-power embedded GUI for power optimisation techniques.