update uart read for lpc18/43 for testing

1 files changed, 4 insertions, 2 deletions

diff --git a/hw/bsp/board.c b/hw/bsp/board.c
index e208624ba..a22b462d9 100644
--- a/hw/bsp/board.c
+++ b/hw/bsp/board.c
@@ -103,7 +103,8 @@ TU_ATTR_USED int sys_write (int fhdl, const void *buf, size_t count)
 TU_ATTR_USED int sys_read (int fhdl, char *buf, size_t count)
 {
   (void) fhdl;
-  return SEGGER_RTT_Read(0, buf, count);
+  int rd = (int) SEGGER_RTT_Read(0, buf, count);
+  return (rd > 0) ? rd : -1;
 }
 #endif
 
@@ -143,7 +144,8 @@ TU_ATTR_USED int sys_write (int fhdl, const void *buf, size_t count)
 TU_ATTR_USED int sys_read (int fhdl, char *buf, size_t count)
 {
   (void) fhdl;
-  return board_uart_read((uint8_t*) buf, (int) count);
+  int rd = board_uart_read((uint8_t*) buf, (int) count);
+  return (rd > 0) ? rd : -1;
 }
 
 #endif