From 78a9579e0996d7c9d19916cd6aef4486ca854ebd Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Mon, 25 May 2020 10:46:53 +0200
Subject: [PATCH] cores/uart/RS232PHYTX: fix startbit duration by pre-loading
 phase_accumulator_tx to tuning_word.

---
 litex/soc/cores/uart.py | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/litex/soc/cores/uart.py b/litex/soc/cores/uart.py
index eafbe6c03..011fe5503 100644
--- a/litex/soc/cores/uart.py
+++ b/litex/soc/cores/uart.py
@@ -99,7 +99,8 @@ class RS232PHYTX(Module):
             If(self.sink.valid & ~tx_busy & ~self.sink.ready,
                 tx_reg.eq(self.sink.data),
                 tx_bitcount.eq(0),
-                tx_busy.eq(1)
+                tx_busy.eq(1),
+                pads.tx.eq(0)
             ).Elif(uart_clk_txen & tx_busy,
                 tx_bitcount.eq(tx_bitcount + 1),
                 If(tx_bitcount == 8,
@@ -112,17 +113,13 @@ class RS232PHYTX(Module):
                     pads.tx.eq(tx_reg[0]),
                     tx_reg.eq(Cat(tx_reg[1:], 0))
                 )
-            ).Elif(tx_busy,
-                If(tx_bitcount == 0,
-                    pads.tx.eq(0)
-                )
             )
         ]
         self.sync += [
                 If(tx_busy,
                     Cat(phase_accumulator_tx, uart_clk_txen).eq(phase_accumulator_tx + tuning_word)
                 ).Else(
-                    Cat(phase_accumulator_tx, uart_clk_txen).eq(0)
+                    Cat(phase_accumulator_tx, uart_clk_txen).eq(tuning_word)
                 )
         ]