diff --git a/cc2520.h b/cc2520.h
index 01a0b5b..4c2ac02 100644
--- a/cc2520.h
+++ b/cc2520.h
@@ -108,6 +108,7 @@ struct cc2520_gpio_state {
 	unsigned int sfd_irq;
 };
 
+// DEPRECATED
 struct cc2520_state {
 	// Hardware
 	struct cc2520_gpio_state gpios;
@@ -220,8 +221,6 @@ typedef union cc2520_fifopctrl {
     } f;
 } cc2520_fifopctrl_t;
 
-
-
 typedef union cc2520_frmfilt0 {
     u8 value;
     struct {
@@ -261,8 +260,6 @@ typedef union cc2520_rxctrl {
     u8 value;
 } cc2520_rxctrl_t;
 
-
-
 typedef union cc2520_fsctrl {
     u8 value;
 } cc2520_fsctrl_t;
diff --git a/interface.c b/interface.c
index 78204cd..4cc92b3 100644
--- a/interface.c
+++ b/interface.c
@@ -12,6 +12,7 @@
 #include "cc2520.h"
 #include "interface.h"
 #include "radio.h"
+#include "sack.h"
 
 struct cc2520_interface *interface_bottom;
 
@@ -44,6 +45,7 @@ static void cc2520_interface_rx_done(u8 *buf, u8 len);
 static void interface_ioctl_set_channel(struct cc2520_set_channel_data *data);
 static void interface_ioctl_set_address(struct cc2520_set_address_data *data);
 static void interface_ioctl_set_txpower(struct cc2520_set_txpower_data *data);
+static void interface_ioctl_set_ack(struct cc2520_set_ack_data *data);
 
 static long interface_ioctl(struct file *file,
 		 unsigned int ioctl_num,
@@ -156,6 +158,9 @@ static long interface_ioctl(struct file *file,
 		case CC2520_IO_RADIO_SET_TXPOWER:
 			interface_ioctl_set_txpower((struct cc2520_set_txpower_data *) ioctl_param);
 			break;
+		case CC2520_IO_RADIO_SET_ACK:
+			interface_ioctl_set_ack((struct cc2520_set_ack_data*) ioctl_param);
+			break;
 	}
 
 	return 0;
@@ -220,6 +225,21 @@ static void interface_ioctl_set_txpower(struct cc2520_set_txpower_data *data)
 	cc2520_radio_set_txpower(ldata.txpower);
 }
 
+static void interface_ioctl_set_ack(struct cc2520_set_ack_data *data)
+{
+	int result;
+	struct cc2520_set_ack_data ldata;
+	result = copy_from_user(&ldata, data, sizeof(struct cc2520_set_ack_data));
+
+	if (result) {
+		printk(KERN_INFO "[cc2520] - an error occurred setting soft ack\n");
+		return;
+	}
+
+	printk(KERN_INFO "[cc2520] - setting softack timeout\n");
+	cc2520_sack_set_timeout(ldata.timeout);
+}
+
 /////////////////
 // init/free 
 ///////////////////
diff --git a/ioctl.h b/ioctl.h
index 9511da3..4c37474 100644
--- a/ioctl.h
+++ b/ioctl.h
@@ -6,6 +6,7 @@
 #include <inttypes.h>
 typedef uint8_t u8;
 typedef uint16_t u16;
+typedef uint32_t u32;
 typedef uint64_t u64;
 #endif
 
@@ -19,6 +20,10 @@ struct cc2520_set_address_data {
 	u16 pan_id;
 };
 
+struct cc2520_set_ack_data {
+	u32 timeout;
+};
+
 // Possible TX Powers:
 #define CC2520_TXPOWER_5DBM 0xF7
 #define CC2520_TXPOWER_3DBM 0xF2
@@ -39,4 +44,5 @@ struct cc2520_set_txpower_data {
 #define CC2520_IO_RADIO_OFF _IO(BASE, 2)
 #define CC2520_IO_RADIO_SET_CHANNEL _IOW(BASE, 3, struct cc2520_set_channel_data)
 #define CC2520_IO_RADIO_SET_ADDRESS _IOW(BASE, 4, struct cc2520_set_address_data)
-#define CC2520_IO_RADIO_SET_TXPOWER _IOW(BASE, 5, struct cc2520_set_txpower_data)
\ No newline at end of file
+#define CC2520_IO_RADIO_SET_TXPOWER _IOW(BASE, 5, struct cc2520_set_txpower_data)
+#define CC2520_IO_RADIO_SET_ACK _IOW(BASE, 6, struct cc2520_set_ack_data)
\ No newline at end of file
diff --git a/sack.c b/sack.c
index 9fd79d1..514d652 100644
--- a/sack.c
+++ b/sack.c
@@ -14,6 +14,7 @@ static int cc2520_sack_tx(u8 * buf, u8 len);
 static void cc2520_sack_tx_done(u8 status);
 static void cc2520_sack_rx_done(u8 *buf, u8 len);
 static enum hrtimer_restart cc2520_sack_timer_cb(struct hrtimer *timer);
+static void cc2520_sack_start_timer(void);
 
 // Two pieces to software acknowledgements:
 // 1 - Taking packets we're transmitting, setting an ACK flag
@@ -33,7 +34,7 @@ static enum hrtimer_restart cc2520_sack_timer_cb(struct hrtimer *timer);
 static u8 *ack_buf;
 static u8 *cur_tx_buf;
 static struct hrtimer timeout_timer;
-
+static int ack_timeout; //in microseconds
 
 enum cc2520_sack_state_enum {
 	CC2520_SACK_IDLE,
@@ -47,8 +48,6 @@ static spinlock_t sack_sl;
 
 int cc2520_sack_init()
 {
-	ktime_t kt;
-
 	sack_top->tx = cc2520_sack_tx;
 	sack_bottom->tx_done = cc2520_sack_tx_done;
 	sack_bottom->rx_done = cc2520_sack_rx_done;
@@ -63,13 +62,9 @@ int cc2520_sack_init()
 		goto error;
 	}
 
-    // Create a 100uS time period.
-    kt=ktime_set(10,100000);
-
 	hrtimer_init(&timeout_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
     timeout_timer.function = &cc2520_sack_timer_cb; // callback
-    //hrtimer_start(&timeout_timer, kt, HRTIMER_MODE_REL);
-
+    
 	spin_lock_init(&sack_sl);
 	sack_state = CC2520_SACK_IDLE;
 
@@ -102,6 +97,19 @@ void cc2520_sack_free()
 	hrtimer_cancel(&timeout_timer);
 }
 
+void cc2520_sack_set_timeout(int timeout)
+{
+	ack_timeout = timeout;
+}
+
+static void cc2520_sack_start_timer()
+{
+	// Create a 100uS time period.
+    ktime_t kt;
+    kt=ktime_set(10,100000);
+	hrtimer_start(&timeout_timer, kt, HRTIMER_MODE_REL);
+}
+
 static int cc2520_sack_tx(u8 * buf, u8 len)
 {
 	spin_lock(&sack_sl);
@@ -116,7 +124,7 @@ static int cc2520_sack_tx(u8 * buf, u8 len)
 	spin_unlock(&sack_sl);
 
 	memcpy(cur_tx_buf, buf, len);
-	
+
 	return sack_bottom->tx(cur_tx_buf, len);
 }
 
@@ -127,14 +135,16 @@ static void cc2520_sack_tx_done(u8 status)
 		if (cc2520_packet_requires_ack_wait(cur_tx_buf)) {
 			printk(KERN_INFO "[cc2520] - Entering TX wait state.\n");
 			sack_state = CC2520_SACK_TX_WAIT;
-			//spin_unlock(&sack_sl);
+			spin_unlock(&sack_sl);
+
+
+			// Start hr timer.
 		}
-		//else {
-			// do we need to wait for an ACK
+		else {
 			sack_state = CC2520_SACK_IDLE;
 			spin_unlock(&sack_sl);
 			sack_top->tx_done(status);
-		//}
+		}
 	}
 	else if (sack_state == CC2520_SACK_TX_ACK) {
 		sack_state = CC2520_SACK_IDLE;
diff --git a/sack.h b/sack.h
index 1d98ee9..b91ced0 100644
--- a/sack.h
+++ b/sack.h
@@ -8,5 +8,6 @@ extern struct cc2520_interface *sack_bottom;
 
 int cc2520_sack_init(void);
 void cc2520_sack_free(void);
+void cc2520_sack_set_timeout(int timeout);
 
 #endif
\ No newline at end of file