diff --git a/sw/src/userspace/puzzlecmd.cpp b/sw/src/userspace/puzzlecmd.cpp
index e30a034..2704aeb 100644
--- a/sw/src/userspace/puzzlecmd.cpp
+++ b/sw/src/userspace/puzzlecmd.cpp
@@ -26,6 +26,7 @@ std::string trigger_mode_to_string(puzzlefw::TriggerMode mode)
     switch (mode) {
         case TriggerMode::TRIG_AUTO: return "auto";
         case TriggerMode::TRIG_EXTERNAL: return "external";
+        case TriggerMode::TRIG_EXTERNAL_ONCE: return "external-once";
         default: return "none";
     }
 }
@@ -206,6 +207,7 @@ int main(int argc, char **argv)
         OPT_CLEAR_DMA, OPT_CLEAR_TIMESTAMP, OPT_CLEAR_RANGE,
         OPT_ACQUISITION_ON, OPT_ACQUISITION_OFF, OPT_CHANNELS,
         OPT_TRIGGER_NONE, OPT_TRIGGER_AUTO, OPT_TRIGGER_EXT,
+        OPT_TRIGGER_EXT_ONCE,
         OPT_TRIGGER_CHANNEL, OPT_TRIGGER_RISING, OPT_TRIGGER_FALLING,
         OPT_TRIGGER_DELAY, OPT_TRIGGER,
         OPT_RECORD_LEN, OPT_DIVISOR, OPT_AVERAGE, OPT_DECIMATE, OPT_SHIFT,
@@ -226,6 +228,7 @@ int main(int argc, char **argv)
         {"trigger-none",      0, 0, OPT_TRIGGER_NONE},
         {"trigger-auto",      0, 0, OPT_TRIGGER_AUTO},
         {"trigger-ext",       0, 0, OPT_TRIGGER_EXT},
+        {"trigger-ext-once",  0, 0, OPT_TRIGGER_EXT_ONCE},
         {"trigger-channel",   1, 0, OPT_TRIGGER_CHANNEL},
         {"trigger-rising",    0, 0, OPT_TRIGGER_RISING},
         {"trigger-falling",   0, 0, OPT_TRIGGER_FALLING},
@@ -264,6 +267,7 @@ int main(int argc, char **argv)
         "  --trigger-none        Disable triggering.\n"
         "  --trigger-auto        Enable continuous triggering.\n"
         "  --trigger-ext         Enable external trigger.\n"
+        "  --trigger-ext-once    Enable external trigger once.\n"
         "  --trigger-channel N   Select trigger input channel (range 0 to 3)."
         "\n"
         "  --trigger-rising      Trigger on rising edge.\n"
@@ -359,6 +363,9 @@ int main(int argc, char **argv)
             case OPT_TRIGGER_EXT:
                 args.trigger_mode = puzzlefw::TRIG_EXTERNAL;
                 break;
+            case OPT_TRIGGER_EXT_ONCE:
+                args.trigger_mode = puzzlefw::TRIG_EXTERNAL_ONCE;
+                break;
             case OPT_TRIGGER_CHANNEL:
                 args.trigger_channel = parse_int(optarg, ok);
                 if (!ok
diff --git a/sw/src/userspace/puzzlefw.hpp b/sw/src/userspace/puzzlefw.hpp
index e7ce952..4556169 100644
--- a/sw/src/userspace/puzzlefw.hpp
+++ b/sw/src/userspace/puzzlefw.hpp
@@ -88,9 +88,10 @@ static inline void sync_dma()
 
 /** Trigger modes. */
 enum TriggerMode {
-    TRIG_NONE = 0,      // trigger disabled, manual trigger only
-    TRIG_AUTO = 1,      // continuous triggering
-    TRIG_EXTERNAL = 2   // external triggering
+    TRIG_NONE = 0,          // trigger disabled, manual trigger only
+    TRIG_AUTO = 1,          // continuous triggering
+    TRIG_EXTERNAL = 2,      // external triggering
+    TRIG_EXTERNAL_ONCE = 3  // external trigger once
 };
 
 
@@ -267,6 +268,9 @@ public:
         if ((v & 0x02) != 0) {
             return TRIG_EXTERNAL;
         }
+        if ((v & 0x04) != 0) {
+            return TRIG_EXTERNAL_ONCE;
+        }
         return TRIG_NONE;
     }
 
@@ -274,13 +278,16 @@ public:
     void set_trigger_mode(TriggerMode mode)
     {
         uint32_t v = read_reg(REG_TRIGGER_MODE);
-        v &= 0xfc;
+        v &= 0xf0;
         if (mode == TRIG_AUTO) {
             v |= 0x01;
         }
         if (mode == TRIG_EXTERNAL) {
             v |= 0x02;
         }
+        if (mode == TRIG_EXTERNAL_ONCE) {
+            v |= 0x04;
+        }
         write_reg(REG_TRIGGER_MODE, v);
     }