From 724f8db1b1babb9a44d2e9654656fee5750e1e41 Mon Sep 17 00:00:00 2001
From: Paul Mathieu <paul@ponteilla.net>
Date: Sat, 28 Jun 2025 18:21:11 -0700
Subject: [PATCH] mbv: fix async uart2 app. it works!

---
 mbv/apps/async/uart2.cc | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/mbv/apps/async/uart2.cc b/mbv/apps/async/uart2.cc
index f6c9fbb..f00bb60 100644
--- a/mbv/apps/async/uart2.cc
+++ b/mbv/apps/async/uart2.cc
@@ -45,10 +45,15 @@ void StartReceiving() {
 }
 
 void StartSending() {
-    if (tx_ring_buffer.AvailableData() > 0 && sending < 1) {
-        sending += 1;
-        XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(), 1);
+    if (sending > 0) {
+        return;
     }
+    size_t tosend = tx_ring_buffer.ContiguousAvailableData();
+    if (tosend < 1) {
+        return;
+    }
+    sending += 1;
+    XUartLite_Send(uart0, tx_ring_buffer.RawReadPointer(), tosend);
 }
 
 std::byte UartReadByte() {
@@ -91,17 +96,14 @@ void UartWriteCrash(std::span<const std::byte> data) {
     }
     while (XUartLite_IsSending(uart0)) {
     }
+    XUartLite_Send(uart0, nullptr, 0);  // reset buffer before enabling interrupts
     XUartLite_EnableInterrupt(uart0);
 }
 
 void UartEcho() {
     while (1) {
-        gpio0->data = tx_ring_buffer.AvailableData();
-
         std::byte c = UartReadByte();
         UartWriteByte(c);
-
-        //gpio0->data = uart0->Stats.ReceiveOverrunErrors;
     }
 }