triyng a uart from scratch... not yet working...

1 files changed, 101 insertions, 0 deletions

diff --git a/src/UART.bs b/src/UART.bs
new file mode 100644
index 0000000..f837949
--- /dev/null
+++ b/src/UART.bs
@@ -0,0 +1,101 @@
+package UART where
+
+import GetPut
+import Util
+
+interface Clock =
+  clk :: Bool
+
+defaultClock :: Clock
+defaultClock =
+  interface Clock
+    clk = True
+
+mkDivider :: Integer -> Clock -> Module Clock
+mkDivider divisor clockIn =
+  module
+    count <- mkReg 0
+
+    rules
+      "increment_divider": when clockIn.clk ==> do
+        if count == fromInteger divisor then do
+          count := 0
+        else
+          count := count + 1
+
+    interface Clock
+      clk = count == 0
+  
+interface ShiftRegister =
+  get :: Get (Bit 1)
+  put :: Put (Bit 1)
+
+mkShiftRegister :: Module ShiftRegister
+mkShiftRegister =
+  module
+    reg :: Reg (Bit 8) <- mkReg 0
+
+    interface ShiftRegister
+      get = interface Get
+              get = return 0
+      put = interface Put
+              put bit = do
+                return ()
+
+-- An 8n1 UART.
+interface UART =
+  -- The RX pin.
+  rxPin :: Bit 1 -> Action
+  -- The TX pin.
+  txPin :: Bit 1
+
+  -- Reads a byte from the UART.
+  rxByte :: Get (Bit 8)
+  -- Writes a byte to the UART.
+  txByte :: Put (Bit 8)
+
+mkUART :: Integer -> Module UART
+mkUART baudDivisor =
+  module
+    baud <- mkDivider baudDivisor defaultClock
+
+    count :: Reg (Bit 4) <- mkReg 0
+    rules
+      "increment_count": when baud.clk ==> do
+        count := count + 1
+
+    let start = 0
+        d0 = 1
+        d1 = 0
+        d2 = 0
+        d3 = 0
+        d4 = 1
+        d5 = 0
+        d6 = 0
+        d7 = 0
+        stop = 1
+
+    interface UART
+      rxPin _bit = when_ baud.clk $ do
+        return () -- TODO
+      txPin = case count of
+                0 -> start
+                1 -> d0
+                2 -> d1
+                3 -> d2
+                4 -> d3
+                5 -> d4
+                6 -> d5
+                7 -> d6
+                8 -> d7
+                9 -> stop
+                _ -> 1
+
+      rxByte = interface Get
+                 get = return 0 when False
+      txByte = interface Put
+                 put _ = do
+                   -- TODO
+                   return ()
+
+-- vim: set ft=haskell :