Pulpissimo Synthesis content

[MikkeN]

Hi, 

I have reviewed Pulpissimo code. There is couple of issues (I try to synthesize it):

1. In pulp_soc.sv (line 861) is instatiation of module jtag_tap_top. However this module is not found. Instead there is module tap_top,
should it be instantiated?

2. In soc_clk_rst_gen.sv there is three instatiations of gf22_FLL
Comment says that it is not supported by FPGA
Is this really synthesizable code?
There is comments regarding that it is behavioral coding.

Best Regards,
MikkeN

[fconti]

1. Might be a recent name change, I saw some merge request with respect to that... will check

2. gf22_fll is just a stub for synthesis in an ASIC technology. For simulation you use a behavioral model ( I believe it’s called generic_fll). For synthesis of any kind you’ll have to provide your own clock generator (FLL or PLL).

[MikkeN]

1. Might be a recent name change, I saw some merge request with respect to that... will check

2. gf22_fll is just a stub for synthesis in an ASIC technology. For simulation you use a behavioral model ( I believe it’s called generic_fll). For synthesis of any kind you’ll have to provide your own clock generator (FLL or PLL).

2. Yes, that is what is also assumed. This FLL is instantiated for Soc_clk_reset_gen module and not bypassed in synthesis like it is in FPGA.
So I will now make blackbox for that.

[fconti]

Rgd point 1: jtag_tap_top.sv is in pulpissimo/rtl/pulpissimo/jtag_tap_top.sv : https://github.com/pulp-platform/pulpiss...tap_top.sv . It instantiates a couple modules taken from the jtag_pulp IP: https://github.com/pulp-platform/jtag_pulp .