diff --git a/main.c b/main.c
index 0b34d3c..20d3af9 100644
--- a/main.c
+++ b/main.c
@@ -94,35 +94,14 @@ void reset_counters(void) {
 #endif
 }
 
-// For sending two-byte prefixed messages
-void usb_send_push_ex(uint8_t message_prefix, uint8_t message_part_two, uint8_t* message, uint8_t message_length) {
-    usb_send_buffer[0] = message_prefix;
-    usb_send_buffer[1] = message_part_two;
-    usb_send_buffer[2] = message_length + 3;
-    memcpy(&usb_send_buffer[3], message, message_length);
-    ret_code_t ret = app_usbd_cdc_acm_write(&m_app_cdc_acm, usb_send_buffer, message_length + 3);
-    
-    NRF_LOG_INFO("[ex]Writing message of length %d, ret: %d", message_length + 3, ret);
-}
-
-// void usb_transmit_message(uint8_t message_prefix, uint8_t* message, uint8_t message_length) {
-//     usb_send_buffer[0] = message_prefix;
-//     usb_send_buffer[1] = message_length + 2;
-//     memcpy(&usb_send_buffer[2], message, message_length);
-//     ret_code_t ret = app_usbd_cdc_acm_write(&m_app_cdc_acm, usb_send_buffer, message_length + 2);
-    
-//     NRF_LOG_INFO("[0]Writing message of length %d, ret: %d", message_length + 2, ret);
+// #DO NOT USE THIS. IT BREAKS THE PACKET FORMAT. USE 
+// void usb_send_message_1byte(uint8_t message) {
+//     usb_send_buffer[0] = message;
+//     ret_code_t ret = app_usbd_cdc_acm_write(&m_app_cdc_acm, usb_send_buffer, 1);
+//     NRF_LOG_INFO("[push]Writing message of length %d, ret: %d", 1, ret);
 // }
 
-void usb_send_push(void) {
-    ret_code_t ret = app_usbd_cdc_acm_write(&m_app_cdc_acm, usb_send_buffer, usb_send_buffer_offset);
-    
-    NRF_LOG_INFO("[1]Writing message of length %d, ret: %d", usb_send_buffer_offset, ret);
-    
-    usb_send_buffer_offset = 0; // reset.
-}
-
-// For mushing together small messages into a 64-byte packet:
+// 1. For mushing together small messages into a 64-byte packet:
 void usb_send_append_message(uint8_t message_prefix, uint8_t* message, uint8_t message_length) {
     usb_send_buffer[usb_send_buffer_offset] = message_prefix;
     usb_send_buffer[usb_send_buffer_offset + 1] = message_length + 2;
@@ -136,6 +115,28 @@ void usb_send_append_message(uint8_t message_prefix, uint8_t* message, uint8_t m
     }
 }
 
+
+// 2. For pushing all messages queued with usb_send_append_message
+void usb_send_push(void) {
+    ret_code_t ret = app_usbd_cdc_acm_write(&m_app_cdc_acm, usb_send_buffer, usb_send_buffer_offset);
+    
+    NRF_LOG_INFO("[push]Writing message of length %d, ret: %d", usb_send_buffer_offset, ret);
+    
+    usb_send_buffer_offset = 0; // reset.
+}
+
+// 3. For sending two-byte prefixed messages
+void usb_send_push_ex(uint8_t message_prefix, uint8_t message_part_two, uint8_t* message, uint8_t message_length) {
+    usb_send_buffer[0] = message_prefix;
+    usb_send_buffer[1] = message_part_two;
+    usb_send_buffer[2] = message_length + 3;
+    memcpy(&usb_send_buffer[3], message, message_length);
+    ret_code_t ret = app_usbd_cdc_acm_write(&m_app_cdc_acm, usb_send_buffer, message_length + 3);
+    
+    NRF_LOG_INFO("[push ex]Writing message of length %d, ret: %d", message_length + 3, ret);
+}
+
+
 // length is always `READ_SIZE`
 void write_ic_settings(uint8_t* new_packet) {
     switch (SECOND_NIBBLE(new_packet[0])) {
@@ -151,6 +152,8 @@ void write_ic_settings(uint8_t* new_packet) {
                 ads1298_start_rdatac();
                 ads1298_standby();
                 // #TODO: readback registers into m_info.registers to confirm correct write. 
+                uint8_t message[] = {0x00}; // LENGTH OF ZERO.
+                usb_send_push_ex(CTRL_ACK_WRITE_IC_REGISTER, IC_ID_ADS1298, message, strlen(message));
             #endif
         } break;
         default:
@@ -235,7 +238,9 @@ static void process_new_packet(uint8_t* new_packet) {
                 run_throughput_test = true;
             }
             if (SECOND_NIBBLE(new_packet[0]) == TN_MISC_RTT_REQUEST) {
-                // [↓] #TODO [Later]
+                uint8_t message[] = {0x00}; // LENGTH OF ZERO.
+                usb_send_append_message(CTRL_ACK_RTT_REQUEST, message, strlen(message));
+                usb_send_push();
             }
         } break;
         default:
diff --git a/pca10056/blank/config/custom_board.h b/pca10056/blank/config/custom_board.h
index 3609269..d862c26 100644
--- a/pca10056/blank/config/custom_board.h
+++ b/pca10056/blank/config/custom_board.h
@@ -59,7 +59,7 @@
   // some devices have more than 62 bytes worth of registers, so it may
   // need to be split up into pages. 
   #define CTRL_REGISTER_READBACK        0xC8
-  
+  #define CTRL_ACK_WRITE_IC_REGISTER    0xDF
   #define CTRL_ACK_RTT_REQUEST          0xE0
   
   // %%% IC Identifiers %%%