SOF and POF difference

[Altera_Forum]

Hi,  

 I am new to the fpga and have started working on it. I have a question, what are sof and pof files generated at the end of the compilation. Also why is the sof file wipes off when you power cycle it and the pof does not.  Thanks, Sid

[Altera_Forum]

The answer is in your question... 

SOF is for direct volatile configuration. POF is for non d-volatile programming. That's the difference.  A SOF file programs the FPGA fabric directly (The FPGA's SRAM cells).  The POF file is used to program an external configuration (A FLASH/EEPROM device - not the actual FPGA).  The FPGA firmware will still be erased when you turn off the power to your device. However, in this case it will be able to reload (from the configuration device) once power is turned back on.

[Altera_Forum]

Hello shaiko, 

 According to section 1.7.2 in this document https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/an/an741.pdf the .sof file is used to program qspi. How does it comes together with your answer ?  Thank you! Ran

[Altera_Forum]

--- Quote Start ---  Hello shaiko, How does it comes together with your answer ?  --- Quote End ---   I don't see how it doesn't... Please read 1.7.2 steps# 9 and# 11.   In# 9 you're clearly instructed to program the SOF and not turn off the device afterward. (because doing so will erase it).  SOF stands for SRAM Object File. And SRAM doesn't maintain its contents once power is disconnected...  FLASH memory does maintain its contents once power is disconnected - and this is exactly what the POF is for.

[Altera_Forum]

I answered in your other thread: the .sof first programs the FPGA with the the parallel flash loader to allow the .pof to go through it and program the QSPI.