Re: ISP programming of PROM in slave serial mode. is it poss
There are 3 classical ways to configure your FPGA:
1) You use a cable from your PC to the FPGA, and run a software on your PC to send data through the cable.
2) You use a microcontroller on your board, with an adequate firmware to send data to the FPGA.
3)You use a "boot-PROM" on your board, connected to the FPGA, that configures the FPGA automatically at power-up (FPGA vendors have such special boot-PROMs in their catalogs).
So for 3rd option, you must have to configure it at very first boot up. and that must be by ISP or JTAG. Is there any problem to have a single JTAG (4-pins) connection routing to PROM?
You can program your PROM thru' JTAG and connect your FPGA to this flash in serial or in master mode.
If you don't want then don't connect all devices in a JTAG chain.
Sachin