diff options
| author | Nathan Ringo <nathan@remexre.com> | 2024-09-18 14:09:34 -0500 |
|---|---|---|
| committer | Nathan Ringo <nathan@remexre.com> | 2024-09-18 14:09:34 -0500 |
| commit | d202daead0f05ecb60580fa7be2f23df8c4542fc (patch) | |
| tree | 027a67c9245bb21bc82c7e52dfd7d989f4900821 /src | |
| parent | 46457cc330049bb38c0af9a3f671b33b8f534c55 (diff) | |
Fix the UART TX.
Diffstat (limited to 'src')
| -rw-r--r-- | src/TopSim.bs | 9 | ||||
| -rw-r--r-- | src/Uart.bs | 14 |
2 files changed, 14 insertions, 9 deletions
diff --git a/src/TopSim.bs b/src/TopSim.bs index 5ba7232..93fef14 100644 --- a/src/TopSim.bs +++ b/src/TopSim.bs @@ -1,16 +1,23 @@ package TopSim where +import GetPut import Top +import Uart mkTopSim :: Module Empty mkTopSim = module timer :: Reg (Bit 8) <- mkReg 0 + uart <- mkUart 1 + rules when True ==> do timer := timer + 1 - when (timer == 0xff) ==> do + when (timer == 0x00) ==> uart.send.put 0x81 + when (timer == 0x01) ==> uart.send.put 0x18 + when (timer == 0x02) ==> uart.send.put 0x81 + when (timer == 0x40) ==> do $finish -- vim: set ft=haskell : diff --git a/src/Uart.bs b/src/Uart.bs index f66970c..d79f246 100644 --- a/src/Uart.bs +++ b/src/Uart.bs @@ -32,10 +32,9 @@ data TxState Start (Bit 8) | -- | The UART is about to send a data bit. 'Data b n' transitions to -- 'Data (b >> 1) (n - 1)' by sending a data bit. 'Data b 0' transitions to - -- 'Stop' by sending the last data bit. + -- 'Idle' by sending the last data bit. Being in the 'Idle' state for a + -- clock transmits the stop bit. Data (Bit 8) (Bit 3) - | -- | The UART is about to send the stop bit. Transitions to 'Idle'. - Stop deriving (Bits) -- | The TX side of the UART. @@ -55,7 +54,9 @@ mkTxUart baudClock bufferSize = rules "uart_tx": when baudClock.clk rules - "uart_tx_idle": when Idle <- state ==> do + "uart_tx_idle": when Idle <- state, not fifo.notEmpty ==> do + pin := 1 + "uart_tx_idle_to_start": when Idle <- state, fifo.notEmpty ==> do pin := 1 b <- (toGet fifo).get state := Start b @@ -65,12 +66,9 @@ mkTxUart baudClock bufferSize = "uart_tx_data": when Data b n <- state ==> do pin := b[0:0] if n == 0 then - state := Stop + state := Idle else state := Data (b >> 1) (n - 1) - "uart_tx_stop": when Stop <- state ==> do - pin := 1 - state := Idle interface TxUart pin = pin send = toPut fifo |