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Found and fixed the major architecture issue with the mig 7 used in the arty a7 board.

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mig 7 is completely different from the ddr4 mig in that the internal pll does not general the required clocks. An external mmcm is required to general two inputs clocks and the required user clock.
This commit is contained in:
Ross Thompson 2023-04-15 11:13:28 -05:00
parent c9445384d7
commit d2272c0620
3 changed files with 21 additions and 4 deletions
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2
fpga/constraints/constraints-ArtyA7.xdc
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@ -5,7 +5,7 @@
# clock comes from pin E3 and is 100Mhz
# output of mmcm is /4 => 25Mhz
create_clock -period 25.000 -name mmcm_clkout1 -waveform {0.000 12.500} [get_nets xlnx_ddr3_c0/ui_clk]
#create_clock -period 25.000 -name mmcm_clkout1 -waveform {0.000 12.500} [get_nets xlnx_ddr3_c0/ui_clk]
create_generated_clock -name CLKDiv64_Gen -source [get_pins wallypipelinedsoc/uncore.uncore/sdc.SDC/sd_top/slow_clk_divider/clkMux/I0] -multiply_by 1 -divide_by 2 [get_pins wallypipelinedsoc/uncore.uncore/sdc.SDC/sd_top/slow_clk_divider/clkMux/O]

1
fpga/generator/wally.tcl
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@ -18,6 +18,7 @@ read_ip IP/xlnx_axi_clock_converter.srcs/sources_1/ip/xlnx_axi_clock_converter/x
if {$board=="ArtyA7"} {
read_ip IP/xlnx_ddr3.srcs/sources_1/ip/xlnx_ddr3/xlnx_ddr3.xci
read_ip IP/xlnx_mmcm.srcs/sources_1/ip/xlnx_mmcm/xlnx_mmcm.xci
} else {
read_ip IP/xlnx_ddr4.srcs/sources_1/ip/xlnx_ddr4/xlnx_ddr4.xci
}

22
fpga/src/fpgaTopArtyA7.v
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@ -173,6 +173,8 @@ module fpgaTop
wire ui_clk_sync_rst;
wire CLK208;
wire clk167;
wire clk200;
wire app_sr_active;
wire app_ref_ack;
@ -186,6 +188,20 @@ module fpgaTop
assign cpu_reset = bus_struct_reset;
assign calib = c0_init_calib_complete;
// mmcm
// the ddr3 mig7 requires 2 input clocks
// 1. sys clock which is 167 MHz = ddr3 clock / 4
// 2. a second clock which is 200 MHz
// Wally requires a slower clock. At this point I don't know what speed the atrix 7 will run so I'm initially targetting 25Mhz.
// the mig will output a clock at 1/4 the sys clock or 41Mhz which might work with wally so we may be able to simplify the logic a lot.
xlnx_mmcm xln_mmcm(.clk_out1(clk167),
.clk_out2(clk200),
.clk_out3(CPUCLK),
.reset(reset),
.locked(),
.clk_in1(default_100mhz_clk));
// SD Card Tristate
IOBUF iobufSDCMD(.T(~SDCCmdOE), // iobuf's T is active low
.I(SDCCmdOut),
@ -398,10 +414,10 @@ module fpgaTop
.ddr3_odt(ddr3_odt),
// clocks. I still don't understand why this needs two?
.sys_clk_i(default_100mhz_clk),
.clk_ref_i(default_100mhz_clk),
.sys_clk_i(clk167),
.clk_ref_i(clk200),
.ui_clk(CLK208),
.ui_clk(BUSCLK),
.ui_clk_sync_rst(ui_clk_sync_rst),
.aresetn(~reset),
.sys_rst(reset),