diff --git a/litedram/modules.py b/litedram/modules.py index 8c0ceb4..dee3145 100644 --- a/litedram/modules.py +++ b/litedram/modules.py @@ -535,6 +535,46 @@ class M12L16161A(SDRModule): technology_timings = _TechnologyTimings(tREFI=64e6/4096, tWTR=(2, None), tCCD=(1, None), tRRD=(None, 10)) speedgrade_timings = {"default": _SpeedgradeTimings(tRP=15, tRCD=15, tWR=15, tRFC=(None, 55), tFAW=None, tRAS=40)} +class W9825G6KH6(SDRModule): + """ + Winbond W9825G6KH-6 chip on Mister SDRAM XS board v2.2 + This is the smallest and cheapest module. + running it at 100MHz (1:2 if system clock is 50MHz) + works well on my SoCKit and all 32MB test error free + I get a number of data errors if I run it at 50MHz, + so this defaults to 1:2. If you want to use a higher + system clock (eg 100MHz), you might want to consider + using 1:1 clocking, because the -6 speedgrade + can be clocked up to 166MHz (CL3) or 133MHz (CL2) + Nevertheless I could not get it to work flawlessly + at 1:1 rate, so currently it only runs well at + 50 MHz and 1:2 rate. + """ + # geometry + nbanks = 4 + nrows = 8192 + ncols = 512 + + @staticmethod + def clock_cycles_to_ns(cycles, clk_freq, sdram_rate) -> float: + d = { + "1:1" : 1, + "1:2" : 2, + "1:4" : 4 + } + return cycles / (d[sdram_rate] * clk_freq) / 1e-9 + + def __init__(self, clk_freq, sdram_rate): + # The datasheet specifies tWr in clock cycles, not in + # ns but to me it looks like litedram expects + # ns for these two parameters, so I have to convert them + # to ns first. + tWr = self.clock_cycles_to_ns(2, clk_freq, sdram_rate) + tRRD = self.clock_cycles_to_ns(2, clk_freq, sdram_rate) + self.technology_timings = _TechnologyTimings(tREFI=64e6/8000, tWTR=(2, None), tCCD=(1, None), tRRD=(None, tRRD)) + self.speedgrade_timings = {"default": _SpeedgradeTimings(tRP=15, tRCD=15, tWR=tWr, tRFC=(None, 60), tFAW=None, tRAS=42)} + super().__init__(clk_freq, sdram_rate) + # DDR ---------------------------------------------------------------------------------------------- class DDRModule(SDRAMModule): memtype = "DDR"