Hello All,
I have a question regarding routing an SPI bus through a MAX II CPLD. I am using the set_max_delay to constrain the pin to pin delay on the SPI lines (MISO,MOSI,CLK,CSN), but I have been unable to get the propagation delay below 6-7ns, even when selecting adjacent pins on the package.
For example, here is the timequest report on a test path between two signals (DMAG1 to SPIF2_DI). Note, there is no combinational logic placed between these pins in the VHDL, only an assignment statement (SPIF2_DI <= DMAG1).![]()
Does anyone have any suggestions on how to get this delay down? The SPI clock is 50 MHz, so I really only have a few ns to spare in CPLD propgation delays. The MAX II handbook mentions a fast I/O connection between adjecent LAB and IOE but I am not quite sure how to exploit this.
I have a question regarding routing an SPI bus through a MAX II CPLD. I am using the set_max_delay to constrain the pin to pin delay on the SPI lines (MISO,MOSI,CLK,CSN), but I have been unable to get the propagation delay below 6-7ns, even when selecting adjacent pins on the package.
For example, here is the timequest report on a test path between two signals (DMAG1 to SPIF2_DI). Note, there is no combinational logic placed between these pins in the VHDL, only an assignment statement (SPIF2_DI <= DMAG1).
Does anyone have any suggestions on how to get this delay down? The SPI clock is 50 MHz, so I really only have a few ns to spare in CPLD propgation delays. The MAX II handbook mentions a fast I/O connection between adjecent LAB and IOE but I am not quite sure how to exploit this.