I am new to the ICE40, but I have worked with Spartan3 before. I am trying some of the old projects on my ICEBreaker, in particular a digital pattern generator. This design has a slow part that can run with 12 MHz and a fast part where I try to go as fast as possible (100MHz). The slow part handles the uart communication and the fast part spits out the digital pattern. I managed to run the fast code alone but when I add the slow uart part, I get an error
nextpnr-ice40 -q --freq 12 --up5k --package sg48 --pcf icebreaker.pcf --json patterngen4.json --asc patterngen4.asc ERROR: PLL 'pll_inst' clock input 'CLK$SB_IO_IN' can only drive PLL ERROR: Packing design failed. 0 warnings, 2 error
Does that mean I can run on the ICE40 only with one clock frequency?