diff --git a/EmbeddedMode.txt b/EmbeddedMode.txt
index 45e7217..51fad41 100644
--- a/EmbeddedMode.txt
+++ b/EmbeddedMode.txt
@@ -45,6 +45,15 @@ character. These sigil characters are:
   !        Error messages
   \        Shell messages
 
+Another feature of output processing in embedded mode is that when
+colourized output is enabled (``opt color true``), colourization is
+always implemented by including ANSI escape codes in the output, even on
+Windows. Normally, colourized output on Windows is implemented by
+changing console text attributes.
+
+Shell messages
+--------------
+
 Shell messages are emitted only when in embedded mode. They provide
 additional information to the front-end and consist of a type identifier
 string immediately following the sigil, then optionally a space and
@@ -58,11 +67,18 @@ arguments. Currently, the following shell messages may be emitted:
 
   ~ The command process has accepted a command and is now executing it.
 
-Another feature of output processing in embedded mode is that when
-colourized output is enabled (``opt color true``), colourization is
-always implemented by including ANSI escape codes in the output, even on
-Windows. Normally, colourized output on Windows is implemented by
-changing console text attributes.
+\power-sample-us <period>
+
+  ~ Indicates that power profiling is enabled. The period argument is a
+    decimal number giving the sample period in microseconds.
+
+\power-samples <data>
+
+  ~ Power data captured from the running device. The data argument is a
+    Base64-encoded string. When decoded, it consists of a sequence of
+    32-bit little-endian unsigned integers. Integers with bit 31 set are
+    MAB values, and those without bit 31 set are current consumption
+    readings, in microamps.
 
 Input processing and interruption
 =================================
diff --git a/drivers/fet_core.c b/drivers/fet_core.c
index d4e13ed..86d6351 100644
--- a/drivers/fet_core.c
+++ b/drivers/fet_core.c
@@ -404,6 +404,7 @@ static void power_init(struct fet_device *dev)
 
 	printc("Power profiling enabled: bufsize = %d bytes, %d us/sample\n",
 		dev->proto.argv[1], dev->proto.argv[0]);
+	printc_shell("power-sample-us %d\n", dev->proto.argv[0]);
 
 	dev->base.power_buf = powerbuf_new(POWERBUF_DEFAULT_SAMPLES,
 		dev->proto.argv[0]);
@@ -447,6 +448,23 @@ static int power_end(struct fet_device *dev)
 	return 0;
 }
 
+static void shell_power(const uint8_t *data, int len)
+{
+	while (len > 0) {
+		int plen = 128;
+		char text[256];
+
+		if (plen > len)
+			plen = len;
+
+		base64_encode(data, plen, text, sizeof(text));
+		printc_shell("power-samples %s\n", text);
+
+		len -= plen;
+		data += plen;
+	}
+}
+
 static int power_poll(struct fet_device *dev)
 {
 	address_t mab;
@@ -467,6 +485,8 @@ static int power_poll(struct fet_device *dev)
 		return -1;
 	}
 
+	shell_power(dev->proto.data, dev->proto.datalen);
+
 	mab = powerbuf_last_mab(dev->base.power_buf);
 	for (i = 0; i + 3 < dev->proto.datalen; i += 4) {
 		uint32_t s = LE_LONG(dev->proto.data, i);
diff --git a/util/util.c b/util/util.c
index 0d59c2b..3c9c8bf 100644
--- a/util/util.c
+++ b/util/util.c
@@ -296,3 +296,41 @@ int delay_ms(unsigned int s)
 	return nanosleep(&ts, NULL);
 }
 #endif
+
+int base64_encode(const uint8_t *src, int len, char *dst, int max_len)
+{
+	static const char basis[] =
+	    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	    "abcdefghijklmnopqrstuvwxyz0123456789+/";
+	int i = 0;
+	int k = 0;
+
+	while ((i < len) && (k + 4) < max_len) {
+		int a = src[i++];
+
+		dst[k++] = basis[a >> 2];
+
+		if (i < len) {
+			int b = src[i++];
+
+			dst[k++] = basis[((a & 3) << 4) | (b & 0xf0) >> 4];
+			if (i < len) {
+				int c = src[i++];
+
+				dst[k++] = basis[((b & 0xf) << 2) |
+						 ((c & 0xc0) >> 6)];
+				dst[k++] = basis[c & 0x3f];
+			} else {
+				dst[k++] = basis[(b & 0xf) << 2];
+				dst[k++] = '=';
+			}
+		} else {
+			dst[k++] = basis[(a & 3) << 4];
+			dst[k++] = '=';
+			dst[k++] = '=';
+		}
+	}
+
+	dst[k] = 0;
+	return i;
+}
diff --git a/util/util.h b/util/util.h
index 97460ea..42a5ccb 100644
--- a/util/util.h
+++ b/util/util.h
@@ -61,6 +61,16 @@ char *expand_tilde(const char *path);
 int delay_s(unsigned int s);
 int delay_ms(unsigned int s);
 
+/* Base64 encode a block without breaking into lines. Returns the number
+ * of source bytes encoded. The output is nul-terminated.
+ */
+static inline int base64_encoded_size(int decoded_size)
+{
+	return ((decoded_size + 2) / 3) * 4;
+}
+
+int base64_encode(const uint8_t *src, int len, char *dst, int max_len);
+
 /* printf format for long long args */
 #ifdef __MINGW32__
 #define LLFMT "I64d"