1 files changed, 39 insertions, 33 deletions

diff --git a/examples/host/cdc_msc_hid/src/cdc_app.c b/examples/host/cdc_msc_hid/src/cdc_app.c
index 4c2c5e807..20033981e 100644
--- a/examples/host/cdc_msc_hid/src/cdc_app.c
+++ b/examples/host/cdc_msc_hid/src/cdc_app.c
@@ -28,11 +28,13 @@
 #include "bsp/board_api.h"
 #include "app.h"
 
-static size_t get_console_inputs(uint8_t* buf, size_t bufsize) {
+static size_t console_read(uint8_t *buf, size_t bufsize) {
   size_t count = 0;
   while (count < bufsize) {
-    int ch = board_getchar();
-    if (ch <= 0) { break; }
+    const int ch = board_getchar();
+    if (ch < 0) {
+      break;
+    }
     buf[count] = (uint8_t) ch;
     count++;
   }
@@ -40,46 +42,50 @@ static size_t get_console_inputs(uint8_t* buf, size_t bufsize) {
   return count;
 }
 
+static size_t console_write(const uint8_t *buf, size_t bufsize) {
+  // Use board_uart_write directly for non-blocking behavior.
+  // board_putchar -> sys_write has a blocking retry loop that causes UART RX overrun.
+  int wr = board_uart_write(buf, (int) bufsize);
+  return (wr > 0) ? (size_t) wr : 0;
+}
+
+// forward from console to usbh
+static void console_to_usbh(uint8_t idx) {
+  uint8_t buf[64];
+  size_t  count = console_read(buf, sizeof(buf));
+  if (count > 0) {
+    tuh_cdc_write(idx, buf, count);
+  }
+}
+
 void cdc_app_task(void) {
-  uint8_t buf[64 + 1]; // +1 for extra null character
-  uint32_t const bufsize = sizeof(buf) - 1;
+  const uint8_t idx = 0;
+
+  // Bidirectional forwarding: console <-> host cdc interfaces
+  if (!tuh_cdc_mounted(idx)) {
+    return;
+  }
 
-  uint32_t count = get_console_inputs(buf, bufsize);
-  buf[count] = 0;
+  // usbh -> uart
+  uint8_t  buf[64];
+  uint32_t count = tuh_cdc_read(idx, buf, sizeof(buf));
+  uint32_t wr    = 0;
 
-  // loop over all mounted interfaces
-  for (uint8_t idx = 0; idx < CFG_TUH_CDC; idx++) {
-    if (tuh_cdc_mounted(idx)) {
-      // console --> cdc interfaces
-      if (count > 0) {
-        tuh_cdc_write(idx, buf, count);
-        tuh_cdc_write_flush(idx);
-      }
+  do {
+    // uart write is slow, while waiting forward uart -> usbh else uart rx can be overflow
+    if (count) {
+      wr += console_write(buf + wr, count - wr);
     }
-  }
+    console_to_usbh(idx);
+  } while (wr < count);
+
+  tuh_cdc_write_flush(idx);
 }
 
 //--------------------------------------------------------------------+
 // TinyUSB callbacks
 //--------------------------------------------------------------------+
 
-// Invoked when received new data
-void tuh_cdc_rx_cb(uint8_t idx) {
-  uint8_t buf[64 + 1]; // +1 for extra null character
-  uint32_t const bufsize = sizeof(buf) - 1;
-
-  // forward cdc interfaces -> console
-  const uint32_t count = tuh_cdc_read(idx, buf, bufsize);
-  if (count) {
-    buf[count] = 0;
-    printf("%s", (char*) buf);
-
-    #ifndef __ICCARM__     // TODO IAR doesn't support stream control ?
-    fflush(stdout);// flush right away, else nanolib will wait for newline
-    #endif
-  }
-}
-
 // Invoked when a device with CDC interface is mounted
 // idx is index of cdc interface in the internal pool.
 void tuh_cdc_mount_cb(uint8_t idx) {