diff --git a/source/communication.cpp b/source/communication.cpp
index ec02a42..b5ee28e 100644
--- a/source/communication.cpp
+++ b/source/communication.cpp
@@ -112,22 +112,23 @@ void updateGenerator(unsigned char *cmd)
     if (EM.assert(USBSerial::read(&cmd[1], 2) == 2, Error::BadParamSize)) {
         unsigned int count = cmd[1] | (cmd[2] << 8);
         if (EM.assert(count <= MAX_SAMPLE_BUFFER_SIZE, Error::BadParam)) {
-            if (run_status == RunStatus::Idle) {
+            if (!DAC::isSigGenRunning()) {
                 Samples::Generator.setSize(count);
                 USBSerial::read(
                     reinterpret_cast<uint8_t *>(Samples::Generator.data()),
                     Samples::Generator.bytesize());
-            } else if (run_status == RunStatus::Running) {
-                int more;
-                do {
-                    chThdSleepMicroseconds(10);
-                    more = DAC::sigGenWantsMore();
-                } while (more == -1);
-
-                // Receive streamed samples in half-buffer chunks.
-                USBSerial::read(reinterpret_cast<uint8_t *>(
-                    more == 0 ? Samples::Generator.data() : Samples::Generator.middata()),
-                    Samples::Generator.bytesize() / 2);
+            } else {
+                const int more = DAC::sigGenWantsMore();
+                if (more == -1) {
+                    USBSerial::write(reinterpret_cast<const uint8_t *>("\0"), 1);
+                } else {
+                    USBSerial::write(reinterpret_cast<const uint8_t *>("\1"), 1);
+
+                    // Receive streamed samples in half-buffer chunks.
+                    USBSerial::read(reinterpret_cast<uint8_t *>(
+                        more == 0 ? Samples::Generator.data() : Samples::Generator.middata()),
+                        Samples::Generator.bytesize() / 2);
+                }
             }
         }
     }
diff --git a/source/periph/dac.cpp b/source/periph/dac.cpp
index 1ff8867..35c2908 100644
--- a/source/periph/dac.cpp
+++ b/source/periph/dac.cpp
@@ -61,7 +61,18 @@ void DAC::start(int channel, dacsample_t *buffer, size_t count)
 
 int DAC::sigGenWantsMore()
 {
-    return dacIsDone;
+    if (dacIsDone != -1) {
+        int tmp = dacIsDone;
+        dacIsDone = -1;
+        return tmp;
+    } else {
+        return -1;
+    }
+}
+
+int DAC::isSigGenRunning()
+{
+    return m_driver[1]->state == DAC_ACTIVE;
 }
 
 void DAC::stop(int channel)
diff --git a/source/periph/dac.hpp b/source/periph/dac.hpp
index 4360c26..7250a52 100644
--- a/source/periph/dac.hpp
+++ b/source/periph/dac.hpp
@@ -24,6 +24,7 @@ public:
     static void stop(int channel);
 
     static int sigGenWantsMore();
+    static int isSigGenRunning();
 
 private:
     static DACDriver *m_driver[2];