diff --git a/Makefile b/Makefile
index c647653..d56c8a4 100644
--- a/Makefile
+++ b/Makefile
@@ -68,6 +68,14 @@ NEXTPNR_FLAGS=--um5g-85k --freq 12
 OPENOCD_JTAG_CONFIG=openocd/ecp5-evn.cfg
 OPENOCD_DEVICE_CONFIG=openocd/LFE5UM5G-85F.cfg
 
+# Colorlight 5A-75B
+#LPF=constraints/colorlight_5A-75B.lpf
+#PLL=pll/pll_ehxplll_25MHz.v
+#PACKAGE=CABGA256
+#NEXTPNR_FLAGS=--25k --freq 25
+#OPENOCD_JTAG_CONFIG=openocd/olimex-arm-usb-tiny-h.cfg
+#OPENOCD_DEVICE_CONFIG=openocd/LFE5U-25F.cfg
+
 synth: chiselwatt.bit
 
 chiselwatt.json: insns.hex $(verilog_files) $(PLL) toplevel.v
diff --git a/constraints/colorlight_5A-75B.lpf b/constraints/colorlight_5A-75B.lpf
new file mode 100644
index 0000000..b3eb74a
--- /dev/null
+++ b/constraints/colorlight_5A-75B.lpf
@@ -0,0 +1,25 @@
+# All the I/Os on this board go through bidirectional level shifters that
+# appear to be hardwired as outputs. To get an input pin for UART RX, we
+# use the button I/O which is also routed to connector J19. The downside is
+# we can't use the button for reset.
+
+LOCATE COMP "clock" SITE "P6";
+IOBUF PORT "clock" IO_TYPE=LVCMOS33;
+
+# We need to assign reset to something to keep the tools happy
+LOCATE COMP "reset" SITE "F1";
+IOBUF PORT "reset" PULLMODE=UP IO_TYPE=LVCMOS33;
+
+LOCATE COMP "io_tx" SITE "F3";
+LOCATE COMP "io_rx" SITE "M13";
+
+IOBUF PORT "io_tx" IO_TYPE=LVCMOS33;
+IOBUF PORT "io_rx" IO_TYPE=LVCMOS33;
+
+LOCATE COMP "io_terminate" SITE "G3";
+LOCATE COMP "io_ledB" SITE "P11";
+LOCATE COMP "io_ledC" SITE "G2";
+
+IOBUF PORT "io_terminate" IO_TYPE=LVCMOS33;
+IOBUF PORT "io_ledB" IO_TYPE=LVCMOS25;
+IOBUF PORT "io_ledC" IO_TYPE=LVCMOS33;
diff --git a/pll/pll_ehxplll_25MHz.v b/pll/pll_ehxplll_25MHz.v
new file mode 100644
index 0000000..f48ddd1
--- /dev/null
+++ b/pll/pll_ehxplll_25MHz.v
@@ -0,0 +1,36 @@
+module pll(
+  input  clki,
+  output clko,
+  output lock
+);
+  (* ICP_CURRENT="12" *) (* LPF_RESISTOR="8" *) (* MFG_ENABLE_FILTEROPAMP="1" *) (* MFG_GMCREF_SEL="2" *)
+
+  EHXPLLL #(
+    .PLLRST_ENA("DISABLED"),
+    .INTFB_WAKE("DISABLED"),
+    .STDBY_ENABLE("DISABLED"),
+    .DPHASE_SOURCE("DISABLED"),
+    .CLKOP_FPHASE(0),
+    .CLKOP_CPHASE(11),
+    .OUTDIVIDER_MUXA("DIVA"),
+    .CLKOP_ENABLE("ENABLED"),
+    .CLKOP_DIV(12),
+    .CLKFB_DIV(10),
+    .CLKI_DIV(5),
+    .FEEDBK_PATH("CLKOP")
+  ) pll_i (
+    .CLKI(clki),
+    .CLKFB(clko),
+    .CLKOP(clko),
+    .LOCK(lock),
+    .RST(1'b0),
+    .STDBY(1'b0),
+    .PHASESEL0(1'b0),
+    .PHASESEL1(1'b0),
+    .PHASEDIR(1'b0),
+    .PHASESTEP(1'b0),
+    .PLLWAKESYNC(1'b0),
+    .ENCLKOP(1'b0)
+  );
+
+endmodule