Lattice ECP5 LFE5U-25F-6BG256C: Pin N9 is not working

[yodalee]

I am using the ECP5 develop board icesugar-pro and the FPGA is LFE5U-25F-6BG256C. I tried to connect to the SPI-FLASH on this board. According to the schematic, the FLASH_CLK is connected to port N9.

So I set the lpf file as below:

# top.lpf SPI-FLASH
LOCATE COMP "flash_cs"   SITE "N8";
LOCATE COMP "flash_mosi" SITE "T8";
LOCATE COMP "flash_miso" SITE "T7";
LOCATE COMP "flash_io2"  SITE "M7";
LOCATE COMP "flash_io3"  SITE "N7";
LOCATE COMP "flash_clk"  SITE "N9";

IOBUF PORT "flash_cs"   IO_TYPE=LVCMOS33 DRIVE=4;
IOBUF PORT "flash_clk"  IO_TYPE=LVCMOS33 DRIVE=4;
IOBUF PORT "flash_mosi" IO_TYPE=LVCMOS33 DRIVE=4;
IOBUF PORT "flash_miso" IO_TYPE=LVCMOS33 DRIVE=4;
IOBUF PORT "flash_io2"  IO_TYPE=LVCMOS33 DRIVE=4;
IOBUF PORT "flash_io3"  IO_TYPE=LVCMOS33 DRIVE=4;

and compile my project with following command:

nextpnr-ecp5 --25k --package CABGA256 --speed 6 --json top.json --textcfg top_out.config --lpf top.lpf

However I will get this error:

ERROR: IO pin 'flash_clk$tr_io' constrained to pin 'N9', which does not exist for package 'CABGA256'.
ERROR: Packing design failed.

I have check the prjtrellis database, which in the pio.json file of ECP5 LFE5U-25F do have no port N9.

Is this a setting error? or I just cannot use port N9 to communicate with the flash?

[gatecat]

You need to use USRMCLK for this pin, rather than using it as a regular IO.

[yodalee]

Thank for your reply. Here is what I understand after search the keyword of USRMCLK.

1. Just remove the LOCATE COMP and IOBUF PORT definition of flash_clk in lpf file.
2. In top.sv, I can access the clock with USRMCLK module

   
   module top (
   /* SPI-FLASH */
   output logic flash_cs,
   output logic flash_mosi,
   input flash_miso,
   input flash_io2,
   input flash_io3,
   );

logic tristate = 1'b0; USRMCLK u1(.USRMCLKI(flash_clk), .USRMCLKTS(tristate));

Now I can control the clk to flash by adjust the wire tristate.
Am I right?

[gatecat]

Yeah that should work

[yodalee]

Thanks, let me do some testing.