diff --git a/hw/bsp/at32f402_405/family.c b/hw/bsp/at32f402_405/family.c
index 56d4a7bea..aa1a5b484 100644
--- a/hw/bsp/at32f402_405/family.c
+++ b/hw/bsp/at32f402_405/family.c
@@ -220,7 +220,7 @@ int board_uart_write(void const *buf, int len)
   #else
     (void) buf;
     (void) len;
-    return 0;
+    return -1;
   #endif
 }
 
diff --git a/hw/bsp/at32f403a_407/family.c b/hw/bsp/at32f403a_407/family.c
index 942e15872..cf15ba83a 100644
--- a/hw/bsp/at32f403a_407/family.c
+++ b/hw/bsp/at32f403a_407/family.c
@@ -238,7 +238,7 @@ int board_uart_write(void const *buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/at32f413/family.c b/hw/bsp/at32f413/family.c
index d9af0ae4d..69591b2ba 100644
--- a/hw/bsp/at32f413/family.c
+++ b/hw/bsp/at32f413/family.c
@@ -238,7 +238,7 @@ int board_uart_write(void const *buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/at32f415/family.c b/hw/bsp/at32f415/family.c
index ca205d480..132e0db31 100644
--- a/hw/bsp/at32f415/family.c
+++ b/hw/bsp/at32f415/family.c
@@ -212,7 +212,7 @@ int board_uart_write(void const *buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/at32f423/family.c b/hw/bsp/at32f423/family.c
index 9f13dba07..79ac3fcca 100644
--- a/hw/bsp/at32f423/family.c
+++ b/hw/bsp/at32f423/family.c
@@ -239,7 +239,7 @@ int board_uart_write(void const *buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/at32f425/family.c b/hw/bsp/at32f425/family.c
index 1629ad7c0..75e53b1f7 100644
--- a/hw/bsp/at32f425/family.c
+++ b/hw/bsp/at32f425/family.c
@@ -220,7 +220,7 @@ int board_uart_write(void const *buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/at32f435_437/family.c b/hw/bsp/at32f435_437/family.c
index 59a4fe120..80e200363 100644
--- a/hw/bsp/at32f435_437/family.c
+++ b/hw/bsp/at32f435_437/family.c
@@ -265,7 +265,7 @@ int board_uart_write(void const *buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/at32f45x/family.c b/hw/bsp/at32f45x/family.c
index 27eae861f..42b688b87 100644
--- a/hw/bsp/at32f45x/family.c
+++ b/hw/bsp/at32f45x/family.c
@@ -216,7 +216,7 @@ int board_uart_write(void const *buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/ch32v20x/family.c b/hw/bsp/ch32v20x/family.c
index 221f62107..76024cfde 100644
--- a/hw/bsp/ch32v20x/family.c
+++ b/hw/bsp/ch32v20x/family.c
@@ -220,6 +220,6 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
diff --git a/hw/bsp/ft9xx/family.c b/hw/bsp/ft9xx/family.c
index 5ee134eb0..a1c50e1b7 100644
--- a/hw/bsp/ft9xx/family.c
+++ b/hw/bsp/ft9xx/family.c
@@ -232,10 +232,11 @@ int board_uart_write(void const *buf, int len)
             break;
         }
     }
+    return count;
 #else
     (void) buf; (void) len;
+    return -1;
 #endif
-    return count;
 }
 
 // Get current milliseconds
diff --git a/hw/bsp/gd32vf103/family.c b/hw/bsp/gd32vf103/family.c
index c1dc82bda..8f82b3ada 100644
--- a/hw/bsp/gd32vf103/family.c
+++ b/hw/bsp/gd32vf103/family.c
@@ -174,7 +174,7 @@ int board_uart_write(void const* buf, int len) {
 #else
   (void)buf;
   (void)len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/kinetis_k/family.c b/hw/bsp/kinetis_k/family.c
index 8efab2762..a5af83931 100644
--- a/hw/bsp/kinetis_k/family.c
+++ b/hw/bsp/kinetis_k/family.c
@@ -140,7 +140,7 @@ int board_uart_write(void const *buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/mm32/family.c b/hw/bsp/mm32/family.c
index 14a17f6c5..1538181dc 100644
--- a/hw/bsp/mm32/family.c
+++ b/hw/bsp/mm32/family.c
@@ -167,7 +167,7 @@ int board_uart_write(void const* buf, int len) {
   #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
   #endif
 }
 
diff --git a/hw/bsp/pic32mz/family.c b/hw/bsp/pic32mz/family.c
index 5805e653f..98038b4f7 100644
--- a/hw/bsp/pic32mz/family.c
+++ b/hw/bsp/pic32mz/family.c
@@ -102,7 +102,9 @@ TU_ATTR_WEAK int board_uart_read(uint8_t * buf, int len)
 TU_ATTR_WEAK int board_uart_write(void const * buf, int len)
 {
   (void) buf;
-  return len;
+  (void) len;
+
+  return -1;
 }
 
 #if CFG_TUSB_OS  == OPT_OS_NONE
diff --git a/hw/bsp/rp2040/family.c b/hw/bsp/rp2040/family.c
index a4642face..55feec159 100644
--- a/hw/bsp/rp2040/family.c
+++ b/hw/bsp/rp2040/family.c
@@ -282,7 +282,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32c0/family.c b/hw/bsp/stm32c0/family.c
index 72af3ce7f..ac37045fb 100644
--- a/hw/bsp/stm32c0/family.c
+++ b/hw/bsp/stm32c0/family.c
@@ -193,7 +193,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32f0/family.c b/hw/bsp/stm32f0/family.c
index f413163e5..c77ef4008 100644
--- a/hw/bsp/stm32f0/family.c
+++ b/hw/bsp/stm32f0/family.c
@@ -206,7 +206,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32f1/family.c b/hw/bsp/stm32f1/family.c
index 74e0f53f2..abde44d21 100644
--- a/hw/bsp/stm32f1/family.c
+++ b/hw/bsp/stm32f1/family.c
@@ -246,7 +246,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32f2/family.c b/hw/bsp/stm32f2/family.c
index 051a026c5..260e5e067 100644
--- a/hw/bsp/stm32f2/family.c
+++ b/hw/bsp/stm32f2/family.c
@@ -210,7 +210,7 @@ int board_uart_write(void const* buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32f3/family.c b/hw/bsp/stm32f3/family.c
index 0864d0fad..35e1852e8 100644
--- a/hw/bsp/stm32f3/family.c
+++ b/hw/bsp/stm32f3/family.c
@@ -222,7 +222,7 @@ int board_uart_write(void const* buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32f4/family.c b/hw/bsp/stm32f4/family.c
index f4ef99150..4eea5c7a8 100644
--- a/hw/bsp/stm32f4/family.c
+++ b/hw/bsp/stm32f4/family.c
@@ -295,7 +295,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32f7/family.c b/hw/bsp/stm32f7/family.c
index 078e372d8..7a322591b 100644
--- a/hw/bsp/stm32f7/family.c
+++ b/hw/bsp/stm32f7/family.c
@@ -357,7 +357,7 @@ int board_uart_write(const void *buf, int len) {
 #else
   (void)buf;
   (void)len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32g0/family.c b/hw/bsp/stm32g0/family.c
index d0ff8bac2..cb674ccc9 100644
--- a/hw/bsp/stm32g0/family.c
+++ b/hw/bsp/stm32g0/family.c
@@ -206,7 +206,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32g4/family.c b/hw/bsp/stm32g4/family.c
index 98739ffd5..433f74e2a 100644
--- a/hw/bsp/stm32g4/family.c
+++ b/hw/bsp/stm32g4/family.c
@@ -236,7 +236,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32h5/family.c b/hw/bsp/stm32h5/family.c
index 8298dfaab..f52f94f32 100644
--- a/hw/bsp/stm32h5/family.c
+++ b/hw/bsp/stm32h5/family.c
@@ -238,7 +238,7 @@ int board_uart_write(void const* buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32h7/family.c b/hw/bsp/stm32h7/family.c
index b32f73754..5173c5401 100644
--- a/hw/bsp/stm32h7/family.c
+++ b/hw/bsp/stm32h7/family.c
@@ -328,7 +328,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32h7rs/family.c b/hw/bsp/stm32h7rs/family.c
index 7ae9e5532..b0841c947 100644
--- a/hw/bsp/stm32h7rs/family.c
+++ b/hw/bsp/stm32h7rs/family.c
@@ -490,7 +490,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32l0/family.c b/hw/bsp/stm32l0/family.c
index 930fa2d66..a4a0ebbfe 100644
--- a/hw/bsp/stm32l0/family.c
+++ b/hw/bsp/stm32l0/family.c
@@ -176,7 +176,7 @@ int board_uart_write(void const* buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32l4/family.c b/hw/bsp/stm32l4/family.c
index 7a8acb3de..96de82bd5 100644
--- a/hw/bsp/stm32l4/family.c
+++ b/hw/bsp/stm32l4/family.c
@@ -264,7 +264,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32n6/family.c b/hw/bsp/stm32n6/family.c
index 95578af04..80de20c6a 100644
--- a/hw/bsp/stm32n6/family.c
+++ b/hw/bsp/stm32n6/family.c
@@ -388,7 +388,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32u0/family.c b/hw/bsp/stm32u0/family.c
index 5cf6e1eb2..7bd99fba6 100644
--- a/hw/bsp/stm32u0/family.c
+++ b/hw/bsp/stm32u0/family.c
@@ -199,7 +199,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32u5/family.c b/hw/bsp/stm32u5/family.c
index 41e354351..7969b1c70 100644
--- a/hw/bsp/stm32u5/family.c
+++ b/hw/bsp/stm32u5/family.c
@@ -304,7 +304,7 @@ int board_uart_write(void const *buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/stm32wb/family.c b/hw/bsp/stm32wb/family.c
index d97be2115..1f1da2271 100644
--- a/hw/bsp/stm32wb/family.c
+++ b/hw/bsp/stm32wb/family.c
@@ -196,7 +196,7 @@ int board_uart_write(void const* buf, int len) {
   return count;
 #else
   (void) buf; (void) len;
-  return 0;
+  return -1;
 #endif
 }
 
diff --git a/hw/bsp/xmc4000/family.c b/hw/bsp/xmc4000/family.c
index 1325b784b..7e224d092 100644
--- a/hw/bsp/xmc4000/family.c
+++ b/hw/bsp/xmc4000/family.c
@@ -150,7 +150,7 @@ int board_uart_write(void const* buf, int len) {
 #else
   (void) buf;
   (void) len;
-  return 0;
+  return -1;
 #endif
 }