I am interested in using an STM32 to flash an sof or pof file onto a Cyclone IV FPGA. The sof/pof will be stored in SPI flash memory, and the plan is to use the STM32 as a programmer. I haven't been able to track down any projects that do this but am super keep to learn if and how it could be possible.
Electronic – Program FPGA using STM32
fpgaintel-fpgastm32
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I think from your question you already understand this, but for clarification, this is my usual terminology:
- Programming implies altering some non-volatile device
- Configuration is what the FPGA does when it starts up - it loads its volatile internal memory from non-volatile external memory.
So, as you surmise, the system needs a non-volatile device of some sort which you program on the production line. To Clarify your comment on the USB blaster, it is not a chip... it's a "pod", so you'd have one for your programming station, not one per board:
Anyway, back to the non-volatile storage options:
The "Almost-zero-engineering required" approach uses Altera's configuration flash devices, which are JTAG programmable using something like a USB blaster. You just wire them up like the datasheet says, and away you go. They cost more per MBit than other options, though, so are not often used in volume production.
One more usual approach is a "normal" SPI flash chip. The Cyclone user guide configuration section will list some which are compatible with it, and I believe you can also use the Quartus software to program them via the JTAG of the FPGA they are connected to. More engineering involved, checking you have the right device etc. Also, if you are in volume production, you may not want to be using Quartus on the production line, which which case you may have to provide a separate programming header for the flash chip, and some hardware+software to drive that.
If you have a microcontroller in your system (even on another board...) you could connect that up to the FPGA's JTAG or configuration pins and store the FPGA bitstream in the micro's flash. More engineering involved as you have to have some software to "boot" the FPGA. however, it can make in-field upgrades easier, as often the micro is set up to receive software upgrades already, whereas updating the flash when it hangs directly off the FPGA is often an "opening the box" experience!
The FPGA configuration itself is stored in SRAM (i.e. flip-flops). A newly started FPGA has an empty configuration where typically all pins are in a somewhat idle state (e.g. weak pull-up), and clocks are not forwarded inside the FPGA, so no activity takes place.
From that state, either the FPGA boots actively by accessing an external device (usually, flash memory), or waits until it is configured by external circuitry. Which road is taken usually depends on some resistors on some pins.
The internal block memory can also, but need not, be initialized from configuration data.
Shiny new boards are programmed like all others, by attaching to JTAG and either writing a configuration to the chip, or by poking the chip into writing to flash and subsequently triggering a reconfiguration so the data is loaded.
Best Answer
You can read the FPP configuration of FPGA datasheet which teaches you how to program FPGA with uP(STM32). What you should pay special attention is the MESL configuration and let STM32 use correct timing provide by the FPGA datasheet to load the sof/rbf.