diff --git a/README.md b/README.md
index ace874f..4ced2c1 100644
--- a/README.md
+++ b/README.md
@@ -65,3 +65,13 @@ command:
 ```
 sudo openocd -f interface/ftdi/digilent-hs1.cfg -f interface/ftdi/swd-resistor-hack.cfg -f target/stm32l1.cfg -c "init" -c "reset init" -c "program build/lora.irr.elf verify reset exit"
 ```
+
+Pins
+----
+
+The [pinout guide for the Node151](http://resource.heltec.cn/download/LoRa_Node_151/LoRa_Node_151_Pinout_Diagram.pdf).
+
+The pins PB5-7,9 are used as active low controls for the relays.
+
+The pin PB15 is used as an analog input for an RNG source.  This pin
+should be grounded.
diff --git a/board.c b/board.c
index 5823738..136d592 100644
--- a/board.c
+++ b/board.c
@@ -195,7 +195,7 @@ void BoardInitMcu( void )
 
 	MX_USB_DEVICE_Init();
 
-    AdcInit( &Adc, NC );  // Just initialize ADC
+    AdcInit( &Adc, PB_15 );  // Just initialize ADC
 
 #if defined( SX1261MBXBAS ) || defined( SX1262MBXCAS ) || defined( SX1262MBXDAS )
     SpiInit( &SX126x.Spi, SPI_1, RADIO_MOSI, RADIO_MISO, RADIO_SCLK, NC );
diff --git a/loramac/src/boards/board.h b/loramac/src/boards/board.h
index 5bd8914..14e3336 100644
--- a/loramac/src/boards/board.h
+++ b/loramac/src/boards/board.h
@@ -23,6 +23,8 @@
 #ifndef __BOARD_H__
 #define __BOARD_H__
 
+#include <adc.h>
+
 #ifdef __cplusplus
 extern "C"
 {
@@ -125,6 +127,8 @@ uint8_t GetBoardPowerSource( void );
  */
 Version_t BoardGetVersion( void );
 
+extern Adc_t Adc;
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/main.c b/main.c
index 6984274..2ff4fb2 100644
--- a/main.c
+++ b/main.c
@@ -26,15 +26,19 @@
 
 #include <usbd_cdc_if.h>
 
-#include <strobe_rng_init.h>
-
 #include <string.h>
 
+/* LoRaMac headers */
 #include <board.h>
-#include <misc.h>
+#include <adc.h>
 #include <radio.h>
 #include <delay.h>
 
+/* lora-irr headers */
+#include <misc.h>
+#include <strobe_rng_init.h>
+
+
 char *
 findeol(char *pos, size_t len)
 {
@@ -202,6 +206,27 @@ radio_seed_rng(void)
 #endif
 }
 
+static void
+analog_seed_rng(void)
+{
+#if 1
+	uint16_t v;
+	int i;
+
+	for (i = 0; i < 256 / 2; i++) {
+		/*
+		 * Capture some ADC data.  If pin is floating, 0xfff
+		 * happens frequently, if pin is grounded, 0 happens
+		 * frequently, filter these values out.
+		 */
+		do {
+			v = AdcReadChannel(&Adc, ADC_CHANNEL_21);
+		} while (v == 0 || v == 0xfff);
+		strobe_seed_prng((uint8_t *)&v, sizeof v);
+	}
+#endif
+}
+
 int
 main(void)
 {
@@ -213,6 +238,8 @@ main(void)
 
 	Radio.Init(&revents);
 
+	analog_seed_rng();
+
 	radio_seed_rng();
 
 	strobe_rng_save();