diff --git a/swuart/Makefile b/swuart/Makefile
index 4eec199..ce24083 100644
--- a/swuart/Makefile
+++ b/swuart/Makefile
@@ -4,7 +4,7 @@ LDFLAGS = -static
 LDLIBS = -L../libubb -lubb
 
 MAIN = swuart
-OBJS = swuart.o
+OBJS = test.o swuart.o
 
 .PHONY:		all clean spotless
 
diff --git a/swuart/swuart.c b/swuart/swuart.c
index b5f380c..23dfd25 100644
--- a/swuart/swuart.c
+++ b/swuart/swuart.c
@@ -12,17 +12,13 @@
 
 
 #include <stdbool.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <unistd.h>
 #include <string.h>
 
 #include <ubb/ubb.h>
 #include <ubb/regs4740.h>
 
+#include "swuart.h"
 
-#define	RX	UBB_DAT0
-#define	TX	UBB_DAT1
 
 #define	TIMER	7
 
@@ -121,11 +117,7 @@ static void enable_interrupts(void)
 /* ----- Transmit a block -------------------------------------------------- */
 
 
-struct rx_err {
-	unsigned glitch;	/* unstable start bit */
-	unsigned framing;	/* stop bit wasn't "1" */
-	unsigned overflow;	/* buffer overflow */
-} rx_err;
+static struct swuart_err errors;
 
 
 static int trx(uint8_t *out, int out_size, uint8_t *in, int in_size,
@@ -182,11 +174,11 @@ full:
 		rx = (rx >> 1) | (PIN(rx_mask) ? 0x200 : 0);
 		if (!--rx_bits) {
 			if (rx & 1) {
-				rx_err.glitch++;
+				errors.glitch++;
 			} else if (!(rx & 0x200)) {
-				rx_err.framing++;
+				errors.framing++;
 			} else if (in_len == in_size) {
-				rx_err.overflow++;
+				errors.overflow++;
 			} else {
 				*in++ = rx >> 1;
 				in_len++;
@@ -217,6 +209,25 @@ int swuart_trx(void *out, int out_size, void *in, int in_size,
 }
 
 
+/* ----- Access error counters --------------------------------------------- */
+
+
+unsigned swuart_get_errors(struct swuart_err *res)
+{
+	unsigned sum = errors.glitch+errors.framing+errors.overflow;
+
+	if (res)
+		*res = errors;
+	return sum;
+}
+
+
+void swuart_clear_errors(void)
+{
+	memset(&errors, 0, sizeof(errors));
+}
+
+
 /* ----- Open/close the software UART -------------------------------------- */
 
 
@@ -242,35 +253,3 @@ void swuart_close(void)
 {
 	ubb_close(0);
 }
-
-
-/* ----- Main -------------------------------------------------------------- */
-
-
-static void at_exit(void)
-{
-	swuart_close();
-}
-
-
-int main(int argc, char **argv)
-{
-	uint8_t buf[40];
-	int got, i;
-
-	swuart_open(TX, RX, atoi(argv[1]));
-	atexit(at_exit);
-	while (1) {
-		got = swuart_trx(argv[2], strlen(argv[2]), buf, sizeof(buf),
-		    10000, 100);
-		printf("%d (%d %d %d): ", got,
-		    rx_err.glitch, rx_err.framing, rx_err.overflow);
-		for (i = 0; i != got; i++)
-			if (buf[i] >= ' ' && buf[i] <= '~')
-				printf("%c", buf[i]);
-			else
-				printf("\\%02o", buf[i]);
-		printf("\n");
-		usleep(100);
-	}
-}
diff --git a/swuart/swuart.h b/swuart/swuart.h
new file mode 100644
index 0000000..fd126ef
--- /dev/null
+++ b/swuart/swuart.h
@@ -0,0 +1,35 @@
+/*
+ * include/ubb/swuart.h - Software-implemented UART for UBB
+ *
+ * Written 2012 by Werner Almesberger
+ * Copyright 2012 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef UBB_SWUART_H
+#define UBB_SWUART_H
+
+#include <stdint.h>
+
+
+struct swuart_err {
+	unsigned glitch;	/* unstable start bit */
+	unsigned framing;	/* stop bit wasn't "1" */
+	unsigned overflow;	/* buffer overflow */
+};
+
+
+int swuart_trx(void *out, int out_size, void *in, int in_size,
+    int wait_bits, int idle_bits);
+
+unsigned swuart_get_errors(struct swuart_err *res);
+void swuart_clear_errors(void);
+
+int swuart_open(uint32_t tx, uint32_t rx, int bps);
+void swuart_close(void);
+
+#endif /* !UBB_SWUART_H */
diff --git a/swuart/test.c b/swuart/test.c
new file mode 100644
index 0000000..18c8b2e
--- /dev/null
+++ b/swuart/test.c
@@ -0,0 +1,57 @@
+
+/*
+ * swuart/test.c - Software-implemented UART for UBB
+ *
+ * Written 2012 by Werner Almesberger
+ * Copyright 2012 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <ubb/ubb.h>
+
+#include "swuart.h"
+
+
+#define	RX	UBB_DAT0
+#define	TX	UBB_DAT1
+
+
+static void at_exit(void)
+{
+	swuart_close();
+}
+
+
+int main(int argc, char **argv)
+{
+	uint8_t buf[40];
+	struct swuart_err err;
+	int got, i;
+
+	swuart_open(TX, RX, atoi(argv[1]));
+	atexit(at_exit);
+	while (1) {
+		got = swuart_trx(argv[2], strlen(argv[2]), buf, sizeof(buf),
+		    10000, 100);
+		swuart_get_errors(&err);
+		printf("%d (%d %d %d): ", got,
+		    err.glitch, err.framing, err.overflow);
+		for (i = 0; i != got; i++)
+			if (buf[i] >= ' ' && buf[i] <= '~')
+				printf("%c", buf[i]);
+			else
+				printf("\\%02o", buf[i]);
+		printf("\n");
+		usleep(100);
+	}
+}