diff --git a/ubb-patgen/README b/ubb-patgen/README
index 5d74f19..22eee31 100644
--- a/ubb-patgen/README
+++ b/ubb-patgen/README
@@ -153,6 +153,10 @@ send the pattern immediately.
 Likewise, -t 1 waits for CLK to become 1. -t cannot be used with
 the -C option.
 
+The trigger can also be a sequence, e.g., -t 01 would first wait
+for CLK to become zero (if it isn't already), then wait for it to
+become one.
+
 ubb-patgen usually starts the pattern about 2-10 us after the
 trigger, but this can be delayed by other system activity. An
 extra delay can be added with the option -w, e.g.,
@@ -164,4 +168,5 @@ The trigger signal can be debounced with the option -d, e.g.,
 # ubb-patgen -t 0 -d 100us 0f0
 
 This accepts the trigger only after it has been zero for at least
-100 microseconds.
+100 microseconds. If the trigger is a sequence, debouncing is
+applied at each step.
diff --git a/ubb-patgen/ubb-patgen.c b/ubb-patgen/ubb-patgen.c
index 863d534..6309119 100644
--- a/ubb-patgen/ubb-patgen.c
+++ b/ubb-patgen/ubb-patgen.c
@@ -354,7 +354,7 @@ static void wait_shifted(const struct mmcclk *clk)
 }
 
 
-static void wait_trigger(int trigger, int debounce,
+static void wait_trigger(const char *trigger, int debounce,
     const struct timespec *debounce_ns)
 {
 	struct timespec end, now;
@@ -363,10 +363,11 @@ static void wait_trigger(int trigger, int debounce,
 	 * @@@ could also try to use POSIX per-process timers here. May be
 	 * slightly cleaner but could increase deviations.
 	 */
-	while (1) {
-		while (PIN(UBB_CLK) != trigger);
+	while (*trigger) {
+		while (PIN(UBB_CLK) != *trigger-'0');
 		if (!debounce)
-			return;
+			goto next;
+again:
 		if (clock_gettime(CLOCK_REALTIME, &end)) {
 			perror("clock_gettime");
 			exit(1);
@@ -377,24 +378,27 @@ static void wait_trigger(int trigger, int debounce,
 			end.tv_nsec -= 1000000000;
 			end.tv_sec++;
 		}
-		while (PIN(UBB_CLK) == trigger) {
+		while (PIN(UBB_CLK) == *trigger-'0') {
 			if (clock_gettime(CLOCK_REALTIME, &now)) {
 				perror("clock_gettime");
 				exit(1);
 			}
 			if (now.tv_sec > end.tv_sec)
-				return;
+				goto next;
 			if (now.tv_sec == end.tv_sec &&
 			    now.tv_nsec >= end.tv_nsec)
-				return;
+				goto next;
 		}
+		goto again;
+next:
+		trigger++;
 	}
 }
 
 
 static void mmc_buffer(const struct mmcclk *clk,
     uint8_t first, unsigned long buf, int nibbles, uint32_t mask,
-    int trigger, int debounce, const struct timespec *debounce_ns,
+    const char *trigger, int debounce, const struct timespec *debounce_ns,
     const struct timespec *wait_ns)
 {
 	/*
@@ -442,7 +446,7 @@ static void mmc_buffer(const struct mmcclk *clk,
 
 	realtimize();
 
-	if (trigger != -1)
+	if (trigger)
 		wait_trigger(trigger, debounce, debounce_ns);
 	if (wait_ns->tv_sec || wait_ns->tv_nsec)
 		if (nanosleep(wait_ns, NULL))
@@ -476,7 +480,7 @@ static void mmc_buffer(const struct mmcclk *clk,
 
 static void send_buffer(const struct mmcclk *clk,
     const uint8_t *buf, int nibbles, uint32_t mask,
-    int trigger, int debounce, const struct timespec *debounce_ns,
+    const char *trigger, int debounce, const struct timespec *debounce_ns,
     const struct timespec *wait_ns)
 {
 	unsigned long phys;
@@ -493,7 +497,7 @@ static void send_buffer(const struct mmcclk *clk,
 
 
 static void dma_pattern(const struct mmcclk *clk,
-    const char *pattern, uint32_t mask, int trigger,
+    const char *pattern, uint32_t mask, const char *trigger,
     int debounce, const struct timespec *debounce_ns,
     const struct timespec *wait_ns)
 {
@@ -511,7 +515,7 @@ static void dma_pattern(const struct mmcclk *clk,
 		exit(1);
 	}
 
-	if (trigger != -1) {
+	if (trigger) {
 		PDFUNC = UBB_CLK;
 		IN(UBB_CLK);
 	}
@@ -676,7 +680,7 @@ static void usage(const char *name)
 "usage: %s\n"
 "       %s [-q] -f freq_hz|-i interval_s\n"
 "       %s [-q] [-f freq_hz|-i interval_s] -c [active_s]\n"
-"       %s [-q] [-f freq_hz|-i interval_s] [-C|-t 0|1 [-d debounce_s]]\n"
+"       %s [-q] [-f freq_hz|-i interval_s] [-C|-t 0|1... [-d debounce_s]]\n"
 "         [-w wait_s] [-m mask] [-p] file|pattern\n\n"
 "  -c          output bus clock on CLK without sending a pattern\n"
 "  -C          temporarily output bus clock on CLK (for debugging)\n"
@@ -688,7 +692,7 @@ static void usage(const char *name)
 "  -p          force interpretation of argument as pattern (and not file)\n"
 "  -q          quiet. Don't pretty-print frequencies; don't report clock\n"
 "              differences.\n"
-"  -t 0|1      start pattern when trigger/CLK becomes 0 or 1 respectively\n"
+"  -t 0|1...   start pattern when trigger/CLK has passed through the sequence\n"
 "              (default: start pattern immediately)\n"
 "  -w wait_s   wait between trigger and sending the pattern\n\n"
 "  active_s    keep running that many seconds after setting the clock\n"
@@ -719,7 +723,7 @@ int main(int argc, char **argv)
 	int active_rel;
 	int keep_clk = 1;
 	uint8_t mask = 0xf;
-	int trigger = -1;
+	const char *trigger = NULL;
 	struct timespec debounce_ns;
 	int debounce = 0, debounce_rel;
 	struct timespec wait_ns = { 0, 0 };
@@ -727,6 +731,7 @@ int main(int argc, char **argv)
 	char *end;
 	int c;
 	unsigned long tmp;
+	const char *p;
 
 	while ((c = getopt(argc, argv, "cCd:f:i:m:pqt:w:")) != EOF)
 		switch (c) {
@@ -769,12 +774,12 @@ int main(int argc, char **argv)
 			quiet = 1;
 			break;
 		case 't':
-			if (!strcmp(optarg, "0"))
-				trigger = 0;
-			else if (!strcmp(optarg, "1"))
-				trigger = 1;
-			else
+			trigger = optarg;
+			if (!*trigger)
 				usage(*argv);
+			for (p = trigger; *p; p++)
+				if (*p != '0' && *p != '1')
+					usage(*argv);
 			break;
 		case 'w':
 			if (!duration_timespec(optarg,
@@ -789,14 +794,14 @@ int main(int argc, char **argv)
 
 	if (clkout && clk_only)
 		usage(*argv);
-	if ((clkout || clk_only) && trigger != -1)
+	if ((clkout || clk_only) && trigger)
 		usage(*argv);
 
 	switch (argc-optind) {
 	case 0:
 		if (clk_only)
 			break;
-		if (clkout || force_pattern || trigger != -1)
+		if (clkout || force_pattern || trigger)
 			usage(*argv);
 
 		ubb_open(UBB_ALL);
@@ -857,7 +862,7 @@ int main(int argc, char **argv)
 			perror("nanosleep");
 	if (pattern) {
 		mmcclk_stop();
-		ubb_close(mask << 10 | (trigger == -1 ? 0 : UBB_CLK));
+		ubb_close(mask << 10 | (trigger ? UBB_CLK : 0));
 	} else if (keep_clk) {
 		ubb_close(UBB_CLK);
 	} else {