🛠 Deploying a real-time IoT gateway on Sapphire RV64

Efinix Sapphire RV64 : Configurable 64-bit RISC-V SoC for FPGAs · avance · Configurez le SoC VexiiRiscv pour un traitement réseau critique avec DMA et gestion de la mémoire avancée.

Objectifs

This tutorial aims to configure the VexiiRiscv core as a high-performance IoT gateway. We will leverage vector processing capabilities (Zba/Zbc/Zbs extensions) and memory management to minimize latency during network packet transfers. The focus is on optimizing the 7-stage pipeline for real-time data stream processing, using AXI4 interfaces for DMA and GPIOs for hardware signaling.

Matériel nécessaire

Efinix Titanium T20 or higher FPGA board.
Efinity 2026.1 or newer design tool.
VexiiRiscv core configured in RV64IMACFD_Zba_Zbc_Zbs mode.
External memory interface (DDR3 or LPDDR4x) for packet buffering.
Network interface (Ethernet MAC) connected via AXI4.
JTAG debug module with hardware breakpoint support.

Étapes

Core Configuration: In Efinity, configure VexiiRiscv with 1 core at 400 MHz. Enable Zba/Zbc/Zbs extensions to accelerate shift and bit-counting operations, crucial for network header parsing. Enable SV39 MMU if using a real-time OS.

Memory Management: Configure the shared L2 cache to 512 KB to maximize network data retention. Allocate a non-cacheable memory region for DMA buffers to avoid cache coherency issues during network transfers.

DMA Implementation: Connect the DMA controller via the AXI4 bus. Configure transfer descriptors to move packets from the Ethernet MAC to external RAM without CPU intervention.

Interrupt Handling: Configure interrupts for DMA and GPIOs. Use GPIOs to trigger physical actions (LEDs, relays) based on processed packet content.

Compilation and Loading: Compile firmware with RV64GC optimizations. Load the binary via JTAG. Use the 4 hardware breakpoints to monitor critical processing routines.

Vérification

Use a logic analyzer to verify clock and data signals on the AXI4 bus. Confirm the CPU remains idle during DMA transfers. Check packet processing latency via core cycle counters.

Pour aller plus loin

Explore using multiple cores (up to 4) to parallelize multiple network stream processing. Test performance with HyperRAM for reduced power consumption.

Code examples for this board

gpio_blink_riscv.ino C (RISC-V)
uart_echo_riscv.ino C (RISC-V)
spi_sensor_read.ino C (RISC-V)
i2c_master_write.ino C (RISC-V)
timer_interrupt_handler.ino C (RISC-V)
i2c-bmp280-temperature-6.ino C

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