PROGB pin and INITB Pin in Spartan 3A XC3S50A

[Sink0]

Please take a look at Marcel Majoor post. It is well explained. The XC3S50AN in special got a 1Mbit flash inside the same package with the fpga. A single boot of the FPGA should use about half of that flash, something like 500Kbit. So you have 500kbit to save non-volatile data. If 500kbit is enought for you, you don't need an external flash. If you need more space (as 128Mbit as you commented) than you need an external flash. TIP: if you ae not sure about the size of the flash you need just leave the footprint on your board conected to the FPGA. Unless you are out of space on your board i belive it is the most reasonable choice considering your doubts. You are not going to pay extra money to leave a footprint over there.

Cya

 

[mrflibble]

Hi mr.flibble,

If i select Spartan 3AN XC3S50AN, i need a External Serial flash? Please confirm. I am in the process of board design.

Regards,
V. Prakash

You could consider reading the datasheet that has been mentioned to you three times now in this thread. Please download it and read page 217 (Internal Master SPI Mode). It answers your very question on flash.

 

[prakashvenugopal]

Hi,

I had seen the chapter 10 of Internal Master SPI. Now i am clear about this.

Thanks,
V. Prakash