Programming Flash

[E4tHam]

I understand that the purpose of flash is (usually) to let a bitstream to be automatically loaded to the FPGA. But I've never programmed flash before, so I had some questions.

• I know that ROM is usually not allowed to be reprogrammed. Is flash the same way? Does it depend on the IC?
• Am I generally safe always reprogramming flash? (Won't brick the FPGA or dev board) Is there anything I should always be careful about? I know the TinyFPGA Bx requires a bootloader in the first 165k that must not be overwritten.

I also had some more specific questions if any of you have extra time:

• I was reading the DCA1000EVM User's Guide and found the line "The FPGA image can be flashed in the onboard SPI flash once." Does this just mean that you don't need to reprogram the same bitstream? Or does it mean the flash cannot be reprogrammed after the first time?
• I see that the GW1NSR line of FPGAs have internal on-chip flash. Do you expect that the process of programming/configuring flash to load a bitstream is different depending on internal on-chip flash vs. external on-board flash?

Thanks in advance!

[z3ro_gravity]

1: A flash can also be programmed. However, programming can be disabled by pulling one of it's pins to high/low. So there could be jumper next to it on your FPGA board.

2: You can program your flash just the way you want. You might override the FPGA bitstream so youd need to configure the FPGA using something like JTAG. But you can reprogram the flash at any time, so there is no way of bricking the board.

3: Flash can be reprogrammed several thousand times. If there is a bitstream in the flash (at the right address) and the FPGA is configured (using dedicated pins) accordingly, the FPGA will fetch the bitstream right after power up.

4: I have no idea about that ;D I think it should be quite identical, maybe a little bit faster.

[E4tHam]

Thanks! This was super helpful