diff --git a/ChangeLog b/ChangeLog
index 1db0bd4..a2a28bf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2019-04-25  NIIBE Yutaka  <gniibe@fsij.org>
+
+	* contrib/usart.h (BSCARD1, BSCARD2...): New.
+	(BSCARD): Remove.
+
+	* contrib/usart-stm32f103.c (usart_config_baud): Rename
+	from usart_config_brr, changing API.
+
 2019-04-24  NIIBE Yutaka  <gniibe@fsij.org>
 
 	* mcu/sys-stm32l4.c: New.
diff --git a/contrib/usart-stm32f103.c b/contrib/usart-stm32f103.c
index 198c5b7..7b8c464 100644
--- a/contrib/usart-stm32f103.c
+++ b/contrib/usart-stm32f103.c
@@ -156,20 +156,35 @@ static const struct brr_setting brr_table[] = {
   { B230400, (   9 << 4)|12},
   { B460800, (   4 << 4)|14},
   { B921600, (   2 << 4)|7},
-  { BSCARD,  ( 234 << 4)|6},
+  { BSCARD1,  ( 232 << 4)|8},	/*   9677 */
+  { BSCARD2,  ( 116 << 4)|4},	/*  19354 */
+  { BSCARD4,  (  58 << 4)|2},	/*  38709 */
+  { BSCARD8,  (  29 << 4)|1},	/*  77419 */
+  { BSCARD12, (  19 << 4)|6},	/* 116129 */
+  { BSCARD16, (  14 << 4)|9},	/* 154506 */
+  { BSCARD20, (  11 << 4)|10},	/* 193548 */
 };
 
 
-void
-usart_config_brr (uint8_t dev_no, uint16_t brr_value)
+int
+usart_config_baud (uint8_t dev_no, uint8_t baud_spec)
 {
   struct USART *USARTx = get_usart_dev (dev_no);
   uint32_t save_bits;
+  int i;
+
+  for (i = 0; i < NUM_BAUD; i++)
+    if (brr_table[i].baud_spec == baud_spec)
+      break;
+
+  if (i >= NUM_BAUD)
+    return -1;
 
   save_bits = USARTx->CR1 & (USART_CR1_TE | USART_CR1_RE);
   USARTx->CR1 &= ~(USART_CR1_TE | USART_CR1_RE);
-  USARTx->BRR = brr_value;
+  USARTx->BRR = brr_table[i].brr_value;
   USARTx->CR1 |= save_bits;
+  return 0;
 }
 
 static void
diff --git a/contrib/usart.h b/contrib/usart.h
index af59a16..421e36c 100644
--- a/contrib/usart.h
+++ b/contrib/usart.h
@@ -11,7 +11,13 @@
 #define B230400     26
 #define B460800     27
 #define B921600     28
-#define BSCARD      63
+#define BSCARD1     57
+#define BSCARD2     58
+#define BSCARD4     59
+#define BSCARD8     60
+#define BSCARD12    61
+#define BSCARD16    62
+#define BSCARD20    63
 #define MASK_BAUD 0x3f
 
 /* POSIX supports 5, 6.  USB suppots 16 */
@@ -73,7 +79,7 @@ int usart_write (uint8_t dev_no, char *buf, uint16_t buflen);
 const struct usart_stat *usart_stat (uint8_t dev_no);
 int usart_send_break (uint8_t dev_no);
 void usart_config_clken (uint8_t dev_no, int on);
-void usart_config_brr (uint8_t dev_no, uint16_t brr_value);
+int usart_config_baud (uint8_t dev_no, uint8_t baud_spec);
 
 void usart_read_prepare_poll (uint8_t dev_no, chopstx_poll_cond_t *poll_desc);
 int usart_read_ext (uint8_t dev_no, char *buf, uint16_t buflen, uint32_t *timeout_p);