simplesoc_ecp5: add blinking LED

examples/simplesoc_ecp5.nix

@@ -14,6 +14,8 @@ let
     IOBUF PORT "clk100" IO_TYPE=LVDS;
     LOCATE COMP "serial_tx" SITE "A11";
     IOBUF PORT "serial_tx" IO_TYPE=LVCMOS33;
+    LOCATE COMP "led" SITE "E16";
+    IOBUF PORT "led" IO_TYPE=LVCMOS25;
     EOF
 
     echo -n "--um-45k --speed 8 --package CABGA381" > $out/device

examples/simplesoc_ecp5.py

@@ -29,6 +29,7 @@ class SimpleWishboneSerial(Elaboratable):
 class Top(Elaboratable):
     def __init__(self, firmware):
         self.clk100 = Signal()
+        self.led = Signal()
         self.serial_tx = Signal()
         self.firmware = firmware
 
@@ -39,6 +40,10 @@ class Top(Elaboratable):
         m.domains += cd_sync
         m.d.comb += cd_sync.clk.eq(self.clk100)
 
+        counter = Signal(27)
+        m.d.sync += counter.eq(counter + 1)
+        m.d.comb += self.led.eq(counter[-1])
+
         m.submodules.cpu = cpu = Minerva(with_icache=False, with_dcache=False, with_muldiv=False)
         m.submodules.ram = ram = wishbone.SRAM(Memory(32, 1024, init=self.firmware))
         m.submodules.uart = uart = SimpleWishboneSerial(self.serial_tx, 100e6)
@@ -73,7 +78,7 @@ def main():
 
     top = Top(firmware)
     output = rtlil.convert(Fragment.get(top, None),
-        ports=(top.clk100, top.serial_tx))
+        ports=(top.clk100, top.led, top.serial_tx))
     with open(args.output_file, "w") as f:
         f.write(output)
 

firmware/memory.x

@@ -1,5 +1,5 @@
 MEMORY
 {
-  FLASH : ORIGIN = 0x80000000, LENGTH = 16M
+  FLASH : ORIGIN = 0x00000000, LENGTH = 16K
-  RAM : ORIGIN = 0x81000000, LENGTH = 16K
+  RAM : ORIGIN = 0x0004000, LENGTH = 16K
 }

firmware/src/main.rs

@@ -11,7 +11,7 @@ fn main() -> ! {
     let foo = "hello world\n";
     loop {
         for c in foo.chars() {
-            let mem = 0x1001_3000 as *mut u8;
+            let mem = 0x00400000 as *mut u8;
             unsafe { *mem = c as u8 }
         }
     }