diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7e4221d..463aec2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,8 +12,13 @@ set_property(GLOBAL PROPERTY CXX_STANDARD 17)
 add_compile_options(-Wall)
 
 add_library(robomaster
+    src/message.c
+    src/messages/sdk_connection.c
+    src/messages/led.c
+    src/messages/sdk_mode.c
+    src/messages/set_wheel_speed.c
     src/robomaster.c
-    src/crc.c
+    src/robomastersh.c
 )
 
 target_include_directories(robomaster
@@ -23,10 +28,10 @@ target_include_directories(robomaster
     include
 )
 
-#add_executable(robomastersh
-#    src/robomastersh.c
-#)
-#
-#target_link_libraries(robomastersh
-#    robomaster
-#)
+add_executable(robomastersh
+    src/robomastersh.c
+)
+
+target_link_libraries(robomastersh
+    robomaster
+)
diff --git a/include/led.h b/include/led.h
new file mode 100644
index 0000000..2c13e5f
--- /dev/null
+++ b/include/led.h
@@ -0,0 +1,39 @@
+#pragma once
+
+#include "message.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
+static const uint8_t SET_SYSTEM_LED_CMDID = 0x33;
+
+enum LEDCOMP {
+    LEDCOMP_BOTTOM_BACK = 0x1,
+    LEDCOMP_BOTTOM_FRONT = 0x2,
+    LEDCOMP_BOTTOM_LEFT = 0x4,
+    LEDCOMP_BOTTOM_RIGHT = 0x8,
+    LEDCOMP_BOTTOM_ALL = 0xf,
+    LEDCOMP_TOP_LEFT = 0x10,
+    LEDCOMP_TOP_RIGHT = 0x20,
+    LEDCOMP_TOP_ALL = 0x30,
+    LEDCOMP_ALL = 0x3f
+};
+
+enum LEDEFFECT {
+    LEDEFFECT_OFF = 0,
+    LEDEFFECT_ON = 1,
+    LEDEFFECT_BREATH = 2,
+    LEDEFFECT_FLASH = 3,
+    LEDEFFECT_SCROLLING = 4
+};
+
+void set_system_led (
+		Client session,
+		uint8_t red,
+		uint8_t green,
+		uint8_t blue,
+		enum LEDCOMP comp,
+		uint16_t led_mask,
+		enum LEDEFFECT effect,
+		uint16_t t1,
+		uint16_t t2 );
diff --git a/include/message.h b/include/message.h
new file mode 100644
index 0000000..4d94dbb
--- /dev/null
+++ b/include/message.h
@@ -0,0 +1,167 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#define PACKED __attribute__((__packed__))
+
+struct PACKED Header {
+
+    // The preamble marks the start of a message and is always 0x55
+    uint8_t preamble;
+
+    // The length of the message includes the preamble and CRC16 at the end
+    union {
+        uint16_t length;
+        struct {
+            uint8_t length_l;
+            uint8_t length_h;
+        };
+    };
+
+    // This is a CRC8 checksum for the preamble and length together
+    uint8_t crc;
+
+    // hostbyte of the message sender
+    uint8_t sender;
+
+    // hostbyte of the message receiver
+    uint8_t receiver;
+
+    // Each message has a sequence ID
+    // The Robomaster will respond with the same ID for each request
+    // The value of the sequence ID doesn't matter to the Robomaster
+    // Repeating sequence IDs are acceptable
+    int16_t seq_id;
+
+    // The message attribute flags designate if a response is needed or if the
+    // message is a response.
+    union {
+        uint8_t attribute;
+        struct {
+            uint8_t reserved : 6;
+            bool ack_needed : 1;
+            bool is_ack : 1;
+        };
+    };
+
+    // Each command has a cmdset and cmdid that together make a cmd key
+    uint8_t cmdset;
+    uint8_t cmdid;
+
+};
+
+struct PACKED Footer {
+    uint16_t crc;
+};
+
+struct PACKED SetSystemLedReq {
+
+    struct Header header;
+
+    // Which LEDs on which component to control
+    uint32_t comp_mask;
+    uint16_t led_mask;
+
+    struct {
+        // off, on, flashing, etc.
+        uint8_t effect_mode : 4;
+	// Always 7
+        uint8_t control_mode : 4;
+    };
+
+    // RGB values for the LED color
+    uint8_t red;
+    uint8_t green;
+    uint8_t blue;
+
+    // Always 0
+    uint8_t loop;
+
+    // These time intervals have different meaning depending on effect
+    uint16_t t1;
+    uint16_t t2;
+
+    struct Footer footer;
+
+};
+
+struct PACKED SetSystemLedResp {
+    struct Header header;
+    uint8_t retcode;
+    struct Footer footer;
+};
+
+struct PACKED SetWheelSpeedReq
+{
+    struct Header header;
+    int16_t wheel_speed[4];
+    struct Footer footer;
+};
+
+struct PACKED SetWheelSpeedResp
+{
+    struct Header header;
+    int8_t retcode;
+    struct Footer footer;
+};
+
+struct PACKED SetSdkModeReq {
+    struct Header header;
+    uint8_t enable;
+    struct Footer footer;
+};
+
+struct PACKED SetSdkModeResp {
+    struct Header header;
+    uint8_t retcode;
+    struct Footer footer;
+};
+
+struct PACKED SetSdkConnectionReq {
+    struct Header header;
+    uint8_t control;
+    uint8_t host;
+    uint8_t connection;
+    uint8_t protocol;
+    uint32_t ip_address;
+    uint16_t port;
+    struct Footer footer;
+};
+
+struct PACKED SetSdkConnectionResp {
+    struct Header header;
+    uint8_t retcode;
+    uint8_t state;
+    uint32_t config_ip;
+    struct Footer footer;
+};
+
+union Request {
+    struct Header header;
+    struct SetSdkConnectionReq sdkconn;
+    struct SetSdkModeReq sdkmode;
+    struct SetSystemLedReq led;
+    struct SetWheelSpeedReq wheel;
+};
+union Response {
+    struct Header header;
+    struct SetSdkConnectionResp sdkconn;
+    struct SetSdkModeReq sdkmode;
+    struct SetSystemLedResp led;
+    struct SetWheelSpeedResp wheel;
+};
+union Message {
+    struct Header header;
+    union Request req;
+    union Response resp;
+};
+
+enum MESSAGEERR {
+    MESSAGEERR_NONE,
+    MESSAGEERR_HEADERCRC,
+    MESSAGEERR_FOOTERCRC
+};
+
+enum MESSAGEERR
+message_validate(const union Message* message);
diff --git a/include/robomaster.h b/include/robomaster.h
index 96729e0..503ecea 100644
--- a/include/robomaster.h
+++ b/include/robomaster.h
@@ -1,17 +1,22 @@
 #pragma once
 
-#include <stdlib.h>
-#include <stddef.h>
-#include <inttypes.h>
-#include <stdbool.h>
-
 // Public stuff
-struct Message;
 struct Client;
 typedef struct Client* Client;
-typedef struct Message* Message;
 
-Client client_new(void* buffer, size_t size);
+#include "message.h"
+#include "led.h"
+#include "sdk_connection.h"
+#include "sdk_mode.h"
+#include "wheel.h"
+
+// SIMPLE
+// Create a client
+// Connect to a drone
+// Send messages
+// Poll for responses
+
+Client client_new();
 void client_connect(Client client);
-Message poll_message(Client client);
+void poll_message(Client client, union Message* message);
 
diff --git a/include/sdk_connection.h b/include/sdk_connection.h
new file mode 100644
index 0000000..e755332
--- /dev/null
+++ b/include/sdk_connection.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include "message.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
+static const uint8_t SET_SDK_CONNECTION_CMDID = 0xD4;
+
+enum CONNECTION {
+    CONNECTION_WIFI_AP = 0,
+    CONNECTION_WIFI_STA = 1,
+    CONNECTION_USB_RNDIS = 2
+};
+
+void
+set_sdk_connection(
+		Client session,
+		enum CONNECTION connection_type,
+		uint32_t ip_address,
+		uint16_t port );
diff --git a/include/sdk_mode.h b/include/sdk_mode.h
new file mode 100644
index 0000000..58fd44c
--- /dev/null
+++ b/include/sdk_mode.h
@@ -0,0 +1,11 @@
+#pragma once
+
+#include "message.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
+static const uint8_t SET_SDK_MODE_CMDID = 0xd1;
+
+void
+set_sdk_mode(Client session, bool enable);
diff --git a/include/wheel.h b/include/wheel.h
new file mode 100644
index 0000000..ff4caca
--- /dev/null
+++ b/include/wheel.h
@@ -0,0 +1,16 @@
+#pragma once
+
+#include "message.h"
+
+#include <stdbool.h>
+#include <stdint.h>
+
+static const uint8_t SET_WHEEL_SPEED_CMDID = 0x20;
+
+void
+set_wheel_speed (
+		Client session,
+		int16_t w1,
+		int16_t w2,
+		int16_t w3,
+		int16_t w4 );
diff --git a/src/client.c b/src/client.c
deleted file mode 100644
index 5c8f7ab..0000000
--- a/src/client.c
+++ /dev/null
@@ -1,16 +0,0 @@
-#include "robomaster.h"
-#include "client.h"
-
-Client session_new(void* buffer, size_t size) {
-    struct Client* session = malloc(sizeof(struct Client));
-    if(!buffer)
-        session->buffer = malloc(sizeof(struct Header));
-    else
-        session->buffer = buffer;
-    session->size = 0;
-    session->seq = 0;
-    session->max_size = size;
-    // TODO: Make this configurable
-    session->hostbyte = host2byte(DEFAULT_CLIENT_HOST, DEFAULT_CLIENT_INDEX);
-    return session;
-}
diff --git a/src/client.h b/src/client.h
index 5507151..6aba128 100644
--- a/src/client.h
+++ b/src/client.h
@@ -1,13 +1,9 @@
 #pragma once
 
-#include "connection.h"
+#include <stdint.h>
 
 struct Client {
 
-   void* buffer;
-   size_t max_size;
-   size_t size;
-
    uint8_t hostbyte;
 
    int16_t seq;
@@ -16,6 +12,11 @@ struct Client {
 
 };
 
+// Not sure what these are, but they are used for the hostbyte
+static const uint8_t DEFAULT_CLIENT_HOST = 9;
+static const uint8_t DEFAULT_CLIENT_INDEX = 6;
+static const uint8_t DEFAULT_ROBOT_INDEX = 0;
+
 static inline uint8_t host2byte(uint8_t host, uint8_t index) {
     return index * 32 + host;
 }
@@ -25,8 +26,3 @@ static inline void byte2host(uint8_t b, uint8_t* host, uint8_t* index) {
     *index = b >> 5;
 }
 
-// Not sure what these are for, but they are used for the hostbyte
-static const uint8_t DEFAULT_CLIENT_HOST = 9;
-static const uint8_t DEFAULT_CLIENT_INDEX = 6;
-static const uint8_t DEFAULT_ROBOT_INDEX = 0;
-
diff --git a/src/connection.c b/src/connection.c
deleted file mode 100644
index ca75962..0000000
--- a/src/connection.c
+++ /dev/null
@@ -1,78 +0,0 @@
-
-#include "robomaster.h"
-#include "client.h"
-#include "connection.h"
-#include "message.h"
-
-static struct Connection* connection_new()
-{
-    struct Connection* conn = calloc(sizeof(struct Connection));
-
-    // Request a UDP socket
-    conn->sockfd = socket(AF_INET, SOCK_DGRAM, 0);
- 
-    // Make the socket non-blocking
-    int flags = fcntl(conn->sockfd, F_GETFL);
-    fcntl(conn->sockfd, F_SETFL, flags | O_NONBLOCK);
-
-    // Set the address of the drone
-    conn->addrlen = sizeof(conn->remote_addr);
-    conn->dest_addr.sin_family = AF_INET;
-    conn->dest_addr.sin_port = htons(30030);
-    conn->dest_addr.sin_addr.s_addr = inet_addr("192.168.2.1");
-
-    return conn;
-}
-
-void client_connect(Client client) {
-    client->connection = connection_new();
-
-    sendto(client->connection->sockfd, client->buffer, session_size(session), 0, (struct sockaddr*)&client->connection->dest_addr, client->connection->addrlen);
-}
-
-// TODO: Use union to make all messages same size
-void send_message(Client client, Message message, int length) {
-    sendto(client->connection->sockfd, message, length, 0, (struct sockaddr*)&client->connection->dest_addr, client->connection->addrlen);
-}
-
-Message poll_message(Client client) {
-
-    // Poll for messages
-    static const struct timeval timeout = {-1, 0};
-    fd_set read_fds;
-    FD_ZERO(&read_fds);
-    FD_SET(client->connection->sockfd, &read_fds);
-    int result = select(client->connection->sockfd + 1, &read_fds, NULL, NULL, &timeout);
-
-    // Check for socket polling errors
-    if(result < 0) {
-        perror("message polling failed");
-	exit(EXIT_FAILURE);
-    }
-
-    // Skip if nothing was received yet
-    // TODO: Make a static "empty" message or something
-    if (result == 0) {
-        return NULL;
-    }
-
-    // Read a message from the socket
-    // TODO: Use union to make all messages same size
-    // NOTE: This is never freed, so it's a memory leak
-    void* buffer = malloc(1024);
-    int recvb = recvfrom(client->connection->sockfd, buffer, sizeof(client->max_size), 0, (struct sockaddr*)&client->connection->dest_addr, &client->connection->addrlen);
-
-    // Check for socket read errors
-    if(recvb < 0) {
-        perror("reading socket failed");
-	exit(EXIT_FAILURE);
-    }
-
-    // Check for message errors
-    if(message_validate(buffer)) {
-        perror("invalid message");
-	exit(EXIT_FAILURE);
-    }
-
-    return (Message)buffer;
-}
diff --git a/src/connection.h b/src/connection.h
index de824ba..795f627 100644
--- a/src/connection.h
+++ b/src/connection.h
@@ -1,8 +1,74 @@
 #pragma once
 
+#include "message.h"
+#include "client.h"
+#include "crc.h"
+
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/select.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include <fcntl.h>
+
 struct Connection {
     int sockfd;
     socklen_t addrlen;
-    sockaddr_in remote_addr;
+    struct sockaddr_in remote_addr;
 };
 
+inline
+static
+struct Connection*
+connection_new()
+{
+    struct Connection* conn = malloc(sizeof(struct Connection));
+    memset(conn, 0, sizeof(struct Connection));
+
+    // Request a UDP socket
+    conn->sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+ 
+    // Make the socket non-blocking
+    int flags = fcntl(conn->sockfd, F_GETFL);
+    fcntl(conn->sockfd, F_SETFL, flags | O_NONBLOCK);
+
+    // Set the address of the drone
+    conn->addrlen = sizeof(conn->remote_addr);
+    conn->remote_addr.sin_family = AF_INET;
+    conn->remote_addr.sin_port = htons(30030);
+    conn->remote_addr.sin_addr.s_addr = inet_addr("192.168.2.1");
+
+    return conn;
+}
+
+static
+inline
+void
+req_finalize(struct Client* client, uint8_t cmdset, uint8_t cmdid, size_t length, union Request* req) {
+
+    req->header.preamble = 0x55;
+    req->header.length_l = length & 0xFF;
+    req->header.length_h = (length >> 8) & 0x3 | 4;
+    req->header.crc = crc8(req, 3);
+    req->header.seq_id = client->seq++;
+    req->header.sender = client->hostbyte;
+    // TODO: Figure out what this is supposed to be
+    req->header.receiver = host2byte(DEFAULT_CLIENT_HOST, DEFAULT_ROBOT_INDEX);
+    req->header.ack_needed = true;
+    req->header.cmdset = cmdset;
+    req->header.cmdid = cmdid;
+
+    struct Footer* footer = (void*)req + length - sizeof(struct Footer);
+    uint16_t crc = crc16(req, length - sizeof(struct Footer));
+    footer->crc = crc;
+
+}
+
+inline
+static
+void
+req_send(struct Connection* conn, union Request* req, size_t length) {
+    sendto(conn->sockfd, req, length, 0, (struct sockaddr*)&conn->remote_addr, conn->addrlen);
+}
+
diff --git a/src/crc.c b/src/crc.c
deleted file mode 100644
index b6fc2b6..0000000
--- a/src/crc.c
+++ /dev/null
@@ -1,78 +0,0 @@
-#include <inttypes.h>
-#include <stdlib.h>
-
-static const uint8_t CRC8_TABLE[] =
-{
-    0x00, 0x5e, 0xbc, 0xe2, 0x61, 0x3f, 0xdd, 0x83, 0xc2, 0x9c, 0x7e, 0x20,
-    0xa3, 0xfd, 0x1f, 0x41, 0x9d, 0xc3, 0x21, 0x7f, 0xfc, 0xa2, 0x40, 0x1e,
-    0x5f, 0x01, 0xe3, 0xbd, 0x3e, 0x60, 0x82, 0xdc, 0x23, 0x7d, 0x9f, 0xc1,
-    0x42, 0x1c, 0xfe, 0xa0, 0xe1, 0xbf, 0x5d, 0x03, 0x80, 0xde, 0x3c, 0x62,
-    0xbe, 0xe0, 0x02, 0x5c, 0xdf, 0x81, 0x63, 0x3d, 0x7c, 0x22, 0xc0, 0x9e,
-    0x1d, 0x43, 0xa1, 0xff, 0x46, 0x18, 0xfa, 0xa4, 0x27, 0x79, 0x9b, 0xc5,
-    0x84, 0xda, 0x38, 0x66, 0xe5, 0xbb, 0x59, 0x07, 0xdb, 0x85, 0x67, 0x39,
-    0xba, 0xe4, 0x06, 0x58, 0x19, 0x47, 0xa5, 0xfb, 0x78, 0x26, 0xc4, 0x9a,
-    0x65, 0x3b, 0xd9, 0x87, 0x04, 0x5a, 0xb8, 0xe6, 0xa7, 0xf9, 0x1b, 0x45,
-    0xc6, 0x98, 0x7a, 0x24, 0xf8, 0xa6, 0x44, 0x1a, 0x99, 0xc7, 0x25, 0x7b,
-    0x3a, 0x64, 0x86, 0xd8, 0x5b, 0x05, 0xe7, 0xb9, 0x8c, 0xd2, 0x30, 0x6e,
-    0xed, 0xb3, 0x51, 0x0f, 0x4e, 0x10, 0xf2, 0xac, 0x2f, 0x71, 0x93, 0xcd,
-    0x11, 0x4f, 0xad, 0xf3, 0x70, 0x2e, 0xcc, 0x92, 0xd3, 0x8d, 0x6f, 0x31,
-    0xb2, 0xec, 0x0e, 0x50, 0xaf, 0xf1, 0x13, 0x4d, 0xce, 0x90, 0x72, 0x2c,
-    0x6d, 0x33, 0xd1, 0x8f, 0x0c, 0x52, 0xb0, 0xee, 0x32, 0x6c, 0x8e, 0xd0,
-    0x53, 0x0d, 0xef, 0xb1, 0xf0, 0xae, 0x4c, 0x12, 0x91, 0xcf, 0x2d, 0x73,
-    0xca, 0x94, 0x76, 0x28, 0xab, 0xf5, 0x17, 0x49, 0x08, 0x56, 0xb4, 0xea,
-    0x69, 0x37, 0xd5, 0x8b, 0x57, 0x09, 0xeb, 0xb5, 0x36, 0x68, 0x8a, 0xd4,
-    0x95, 0xcb, 0x29, 0x77, 0xf4, 0xaa, 0x48, 0x16, 0xe9, 0xb7, 0x55, 0x0b,
-    0x88, 0xd6, 0x34, 0x6a, 0x2b, 0x75, 0x97, 0xc9, 0x4a, 0x14, 0xf6, 0xa8,
-    0x74, 0x2a, 0xc8, 0x96, 0x15, 0x4b, 0xa9, 0xf7, 0xb6, 0xe8, 0x0a, 0x54,
-    0xd7, 0x89, 0x6b, 0x35
-};
-
-static const uint16_t CRC16_TABLE[] = 
-{
-    0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf, 0x8c48,
-    0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7, 0x1081, 0x0108,
-    0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e, 0x9cc9, 0x8d40, 0xbfdb,
-    0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876, 0x2102, 0x308b, 0x0210, 0x1399,
-    0x6726, 0x76af, 0x4434, 0x55bd, 0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e,
-    0xfae7, 0xc87c, 0xd9f5, 0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e,
-    0x54b5, 0x453c, 0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd,
-    0xc974, 0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
-    0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3, 0x5285,
-    0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a, 0xdecd, 0xcf44,
-    0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72, 0x6306, 0x728f, 0x4014,
-    0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9, 0xef4e, 0xfec7, 0xcc5c, 0xddd5,
-    0xa96a, 0xb8e3, 0x8a78, 0x9bf1, 0x7387, 0x620e, 0x5095, 0x411c, 0x35a3,
-    0x242a, 0x16b1, 0x0738, 0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862,
-    0x9af9, 0x8b70, 0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e,
-    0xf0b7, 0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
-    0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036, 0x18c1,
-    0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e, 0xa50a, 0xb483,
-    0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5, 0x2942, 0x38cb, 0x0a50,
-    0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd, 0xb58b, 0xa402, 0x9699, 0x8710,
-    0xf3af, 0xe226, 0xd0bd, 0xc134, 0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7,
-    0x6e6e, 0x5cf5, 0x4d7c, 0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1,
-    0xa33a, 0xb2b3, 0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72,
-    0x3efb, 0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
-    0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a, 0xe70e,
-    0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1, 0x6b46, 0x7acf,
-    0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9, 0xf78f, 0xe606, 0xd49d,
-    0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330, 0x7bc7, 0x6a4e, 0x58d5, 0x495c,
-    0x3de3, 0x2c6a, 0x1ef1, 0x0f78
-};
-
-uint8_t crc8(const void* block, size_t length)
-{
-    uint8_t crc = 0x77;
-    const uint8_t* bytes = (uint8_t*)block;
-    while(length--) crc = CRC8_TABLE[crc^*bytes++];
-    return crc;
-}
-
-uint16_t crc16(const void* block, size_t length)
-{
-    uint16_t crc = 0x3692;
-    const uint8_t* bytes = (uint8_t*)block;
-    while(length--)
-        crc = ((crc>>8)&0xFF)^CRC16_TABLE[((crc^*bytes++)&0xFF)];
-    return crc;
-}
diff --git a/src/crc.h b/src/crc.h
index a6adbd6..ebe62de 100644
--- a/src/crc.h
+++ b/src/crc.h
@@ -1,4 +1,86 @@
 #pragma once
 
-uint8_t crc8(const void *block, size_t length);
-uint16_t crc16(const void *block, size_t length);
+#include <inttypes.h>
+#include <stdlib.h>
+
+static const uint8_t CRC8_TABLE[] =
+{
+    0x00, 0x5e, 0xbc, 0xe2, 0x61, 0x3f, 0xdd, 0x83, 0xc2, 0x9c, 0x7e, 0x20,
+    0xa3, 0xfd, 0x1f, 0x41, 0x9d, 0xc3, 0x21, 0x7f, 0xfc, 0xa2, 0x40, 0x1e,
+    0x5f, 0x01, 0xe3, 0xbd, 0x3e, 0x60, 0x82, 0xdc, 0x23, 0x7d, 0x9f, 0xc1,
+    0x42, 0x1c, 0xfe, 0xa0, 0xe1, 0xbf, 0x5d, 0x03, 0x80, 0xde, 0x3c, 0x62,
+    0xbe, 0xe0, 0x02, 0x5c, 0xdf, 0x81, 0x63, 0x3d, 0x7c, 0x22, 0xc0, 0x9e,
+    0x1d, 0x43, 0xa1, 0xff, 0x46, 0x18, 0xfa, 0xa4, 0x27, 0x79, 0x9b, 0xc5,
+    0x84, 0xda, 0x38, 0x66, 0xe5, 0xbb, 0x59, 0x07, 0xdb, 0x85, 0x67, 0x39,
+    0xba, 0xe4, 0x06, 0x58, 0x19, 0x47, 0xa5, 0xfb, 0x78, 0x26, 0xc4, 0x9a,
+    0x65, 0x3b, 0xd9, 0x87, 0x04, 0x5a, 0xb8, 0xe6, 0xa7, 0xf9, 0x1b, 0x45,
+    0xc6, 0x98, 0x7a, 0x24, 0xf8, 0xa6, 0x44, 0x1a, 0x99, 0xc7, 0x25, 0x7b,
+    0x3a, 0x64, 0x86, 0xd8, 0x5b, 0x05, 0xe7, 0xb9, 0x8c, 0xd2, 0x30, 0x6e,
+    0xed, 0xb3, 0x51, 0x0f, 0x4e, 0x10, 0xf2, 0xac, 0x2f, 0x71, 0x93, 0xcd,
+    0x11, 0x4f, 0xad, 0xf3, 0x70, 0x2e, 0xcc, 0x92, 0xd3, 0x8d, 0x6f, 0x31,
+    0xb2, 0xec, 0x0e, 0x50, 0xaf, 0xf1, 0x13, 0x4d, 0xce, 0x90, 0x72, 0x2c,
+    0x6d, 0x33, 0xd1, 0x8f, 0x0c, 0x52, 0xb0, 0xee, 0x32, 0x6c, 0x8e, 0xd0,
+    0x53, 0x0d, 0xef, 0xb1, 0xf0, 0xae, 0x4c, 0x12, 0x91, 0xcf, 0x2d, 0x73,
+    0xca, 0x94, 0x76, 0x28, 0xab, 0xf5, 0x17, 0x49, 0x08, 0x56, 0xb4, 0xea,
+    0x69, 0x37, 0xd5, 0x8b, 0x57, 0x09, 0xeb, 0xb5, 0x36, 0x68, 0x8a, 0xd4,
+    0x95, 0xcb, 0x29, 0x77, 0xf4, 0xaa, 0x48, 0x16, 0xe9, 0xb7, 0x55, 0x0b,
+    0x88, 0xd6, 0x34, 0x6a, 0x2b, 0x75, 0x97, 0xc9, 0x4a, 0x14, 0xf6, 0xa8,
+    0x74, 0x2a, 0xc8, 0x96, 0x15, 0x4b, 0xa9, 0xf7, 0xb6, 0xe8, 0x0a, 0x54,
+    0xd7, 0x89, 0x6b, 0x35
+};
+
+static const uint16_t CRC16_TABLE[] = 
+{
+    0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf, 0x8c48,
+    0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7, 0x1081, 0x0108,
+    0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e, 0x9cc9, 0x8d40, 0xbfdb,
+    0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876, 0x2102, 0x308b, 0x0210, 0x1399,
+    0x6726, 0x76af, 0x4434, 0x55bd, 0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e,
+    0xfae7, 0xc87c, 0xd9f5, 0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e,
+    0x54b5, 0x453c, 0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd,
+    0xc974, 0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
+    0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3, 0x5285,
+    0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a, 0xdecd, 0xcf44,
+    0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72, 0x6306, 0x728f, 0x4014,
+    0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9, 0xef4e, 0xfec7, 0xcc5c, 0xddd5,
+    0xa96a, 0xb8e3, 0x8a78, 0x9bf1, 0x7387, 0x620e, 0x5095, 0x411c, 0x35a3,
+    0x242a, 0x16b1, 0x0738, 0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862,
+    0x9af9, 0x8b70, 0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e,
+    0xf0b7, 0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
+    0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036, 0x18c1,
+    0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e, 0xa50a, 0xb483,
+    0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5, 0x2942, 0x38cb, 0x0a50,
+    0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd, 0xb58b, 0xa402, 0x9699, 0x8710,
+    0xf3af, 0xe226, 0xd0bd, 0xc134, 0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7,
+    0x6e6e, 0x5cf5, 0x4d7c, 0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1,
+    0xa33a, 0xb2b3, 0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72,
+    0x3efb, 0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
+    0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a, 0xe70e,
+    0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1, 0x6b46, 0x7acf,
+    0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9, 0xf78f, 0xe606, 0xd49d,
+    0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330, 0x7bc7, 0x6a4e, 0x58d5, 0x495c,
+    0x3de3, 0x2c6a, 0x1ef1, 0x0f78
+};
+
+static
+inline
+uint8_t
+crc8(const void* block, size_t length)
+{
+    uint8_t crc = 0x77;
+    const uint8_t* bytes = (uint8_t*)block;
+    while(length--) crc = CRC8_TABLE[crc^*bytes++];
+    return crc;
+}
+
+static
+inline
+uint16_t
+crc16(const void* block, size_t length)
+{
+    uint16_t crc = 0x3692;
+    const uint8_t* bytes = (uint8_t*)block;
+    while(length--)
+        crc = ((crc>>8)&0xFF)^CRC16_TABLE[((crc^*bytes++)&0xFF)];
+    return crc;
+}
diff --git a/src/led.h b/src/led.h
deleted file mode 100644
index c5be64c..0000000
--- a/src/led.h
+++ /dev/null
@@ -1,78 +0,0 @@
-#pragma once
-
-#include "robomaster.h"
-#include "message.h"
-
-static const uint8_t SET_SYSTEM_LED_CMDID = 0x33;
-
-enum LEDCOMP {
-    LEDCOMP_BOTTOM_BACK = 0x1,
-    LEDCOMP_BOTTOM_FRONT = 0x2,
-    LEDCOMP_BOTTOM_LEFT = 0x4,
-    LEDCOMP_BOTTOM_RIGHT = 0x8,
-    LEDCOMP_BOTTOM_ALL = 0xf,
-    LEDCOMP_TOP_LEFT = 0x10,
-    LEDCOMP_TOP_RIGHT = 0x20,
-    LEDCOMP_TOP_ALL = 0x30,
-    LEDCOMP_ALL = 0x3f
-};
-
-enum LEDEFFECT {
-    LEDEFFECT_OFF = 0,
-    LEDEFFECT_ON = 1,
-    LEDEFFECT_BREATH = 2,
-    LEDEFFECT_FLASH = 3,
-    LEDEFFECT_SCROLLING = 4
-};
-
-struct PACKED SetSystemLedReq {
-
-    // Which LEDs on which component to control
-    uint32_t comp_mask;
-    uint16_t led_mask;
-
-    struct {
-        // off, on, flashing, etc.
-        uint8_t effect_mode : 4;
-	// Always 7
-        uint8_t control_mode : 4;
-    };
-
-    // RGB values for the LED color
-    uint8_t red;
-    uint8_t green;
-    uint8_t blue;
-
-    // Always 0
-    uint8_t loop;
-
-    // These time intervals have different meaning depending on effect
-    uint16_t t1;
-    uint16_t t2;
-};
-
-struct PACKED SetSystemLedResp {
-    uint8_t retcode;
-};
-
-static
-inline
-const Message
-set_system_led_new (
-		Client session,
-		uint8_t red,
-		uint8_t green,
-		uint8_t blue,
-		enum LEDCOMP comp,
-		uint16_t led_mask,
-		enum LEDEFFECT effect,
-		uint16_t t1,
-		uint16_t t2 ) {
-    const struct SetSystemLedReq msg = {
-        comp, led_mask,
-	{ effect, 7 },
-	red, green, blue,
-	0, t1, t2
-    };
-    return message_new(session, 0x3F, SET_SYSTEM_LED_CMDID, sizeof(msg), &msg);
-}
diff --git a/src/message.c b/src/message.c
new file mode 100644
index 0000000..0c9cb64
--- /dev/null
+++ b/src/message.c
@@ -0,0 +1,16 @@
+#include "message.h"
+#include "crc.h"
+
+enum MESSAGEERR
+message_validate(const union Message* message) {
+
+    uint16_t length = (message->header.length_h & 0x3) * 0xFF + message->header.length_l;
+
+    if(message->header.crc != crc8(message, 3))
+        return MESSAGEERR_HEADERCRC;
+
+    if(message->header.crc != crc16(message, length - sizeof(struct Footer)))
+        return MESSAGEERR_FOOTERCRC;
+
+}
+
diff --git a/src/message.h b/src/message.h
deleted file mode 100644
index 612fb8f..0000000
--- a/src/message.h
+++ /dev/null
@@ -1,117 +0,0 @@
-#pragma once
-
-#include "client.h"
-
-#define PACKED __attribute__((__packed__))
-
-struct PACKED Header {
-
-  // The preamble marks the start of a message and is always 0x55
-  uint8_t preamble;
-
-  // The length of the message includes the preamble and CRC16 at the end
-  union {
-      uint16_t length;
-      struct {
-          uint8_t length_l;
-	  uint8_t length_h;
-      };
-  };
-
-  // This is a CRC8 checksum for the preamble and length together
-  uint8_t crc;
-
-  // hostbyte of the message sender
-  uint8_t sender;
-
-  // hostbyte of the message receiver
-  uint8_t receiver;
-
-  // Each message has a sequence ID
-  // The Robomaster will respond with the same ID for each request
-  // The value of the sequence ID doesn't matter to the Robomaster
-  // Repeating sequence IDs are acceptable
-  union {
-      int16_t seq_id;
-      struct {
-          uint8_t seq_id_l;
-	  uint8_t seq_id_h;
-      };
-  };
-
-  // The message attribute flags designate if a response is needed or if the
-  // message is a response.
-  union {
-    uint8_t attribute;
-    struct {
-      uint8_t reserved : 6;
-      bool ack_needed : 1;
-      bool is_ack : 1;
-    };
-  };
-
-  // Each command has a cmdset and cmdid that together make a cmd key
-  uint8_t cmdset;
-  uint8_t cmdid;
-
-};
-
-struct PACKED Message {
-  struct Header header;
-  uint8_t body[];
-};
-
-struct PACKED Footer {
-  uint16_t crc;
-};
-
-static
-inline
-struct Message*
-message_new(struct Client* session, uint8_t cmdset, uint8_t cmdid, size_t length, const void* body) {
-
-    struct Message* message = session->buffer + session->size;
-    memcpy((void*)message->body, body, length);
-    length += sizeof(struct Header) + sizeof(struct Footer);
-    session->size += length;
-    int16_t seq = session->seq++;
-
-    message->header.preamble = 0x55;
-    message->header.length_l = length & 0xFF;
-    message->header.length_h = (length >> 8) & 0x3 | 4;
-    message->header.crc = crc8(message, 3);
-    message->header.seq_id = seq;
-    message->header.sender = session->hostbyte;
-    message->header.receiver = host2byte(DEFAULT_CLIENT_HOST, DEFAULT_ROBOT_INDEX);
-    message->header.ack_needed = true;
-    message->header.cmdset = cmdset;
-    message->header.cmdid = cmdid;
-
-    struct Footer* footer = (void*)message + length - sizeof(struct Footer);
-    uint16_t crc = crc16(message, length - sizeof(struct Footer));
-    footer->crc = crc;
-
-    return message;
-
-}
-
-enum MESSAGEERR {
-    MESSAGEERR_NONE,
-    MESSAGEERR_HEADERCRC,
-    MESSAGEERR_FOOTERCRC
-}
-
-static
-inline
-enum MESSAGEERR
-message_validate(const struct Message* message) {
-
-    uint16_t length = (message->header->length_h[2] & 0x3) * 0xFF + message->header->length_l[1];
-
-    if(message->header.crc != crc8(message, 3))
-        return MESSAGEERR_HEADERCRC;
-
-    if(message->header.crc != crc16(message, length - sizeof(struct Footer)))
-        return MESSAGEERR_FOOTERCRC;
-
-}
diff --git a/src/messages/led.c b/src/messages/led.c
new file mode 100644
index 0000000..3d6cbdb
--- /dev/null
+++ b/src/messages/led.c
@@ -0,0 +1,33 @@
+#include "message.h"
+#include "connection.h"
+#include "robomaster.h"
+
+void
+set_system_led (
+		Client session,
+		uint8_t red,
+		uint8_t green,
+		uint8_t blue,
+		enum LEDCOMP comp,
+		uint16_t led_mask,
+		enum LEDEFFECT effect,
+		uint16_t t1,
+		uint16_t t2 ) {
+
+    union Request req = {0};
+
+    req.led.comp_mask = comp;
+    req.led.led_mask = led_mask;
+    req.led.effect_mode = effect;
+    req.led.control_mode = 7;
+    req.led.red = red;
+    req.led.green = green;
+    req.led.blue = blue;
+    req.led.loop = 0;
+    req.led.t1 = t1;
+    req.led.t2 = t2;
+
+    req_finalize(session, 0x3F, SET_SYSTEM_LED_CMDID, sizeof(struct SetSystemLedReq), &req);
+    req_send(session->connection, &req, sizeof(struct SetSystemLedReq));
+
+}
diff --git a/src/messages/sdk_connection.c b/src/messages/sdk_connection.c
new file mode 100644
index 0000000..5fc3b01
--- /dev/null
+++ b/src/messages/sdk_connection.c
@@ -0,0 +1,21 @@
+#include "message.h"
+#include "connection.h"
+#include "robomaster.h"
+
+void
+set_sdk_connection(
+		Client session,
+		enum CONNECTION connection_type,
+		uint32_t ip_address,
+		uint16_t port ) {
+
+    union Request req = {0};
+    req.sdkconn.control = 0;
+    req.sdkconn.host = session->hostbyte;
+    req.sdkconn.connection = connection_type;
+    req.sdkconn.protocol = 0;
+    req.sdkconn.ip_address = ip_address;
+    req.sdkconn.port = port;
+    req_finalize(session, 0x3F, SET_SDK_CONNECTION_CMDID, sizeof(struct SetSdkConnectionReq), &req);
+    req_send(session->connection, &req, sizeof(struct SetSdkConnectionReq));
+}
diff --git a/src/messages/sdk_mode.c b/src/messages/sdk_mode.c
new file mode 100644
index 0000000..cef1fdc
--- /dev/null
+++ b/src/messages/sdk_mode.c
@@ -0,0 +1,13 @@
+#include "message.h"
+#include "connection.h"
+#include "robomaster.h"
+
+void
+set_sdk_mode(
+		Client session,
+		bool enable ) {
+    union Request req = {0};
+    req.sdkmode.enable = enable;
+    req_finalize(session, 0x3F, SET_SDK_MODE_CMDID, sizeof(struct SetSdkModeReq), &req);
+    req_send(session->connection, &req, sizeof(struct SetSdkModeReq));
+}
diff --git a/src/messages/set_wheel_speed.c b/src/messages/set_wheel_speed.c
new file mode 100644
index 0000000..c601eff
--- /dev/null
+++ b/src/messages/set_wheel_speed.c
@@ -0,0 +1,19 @@
+#include "message.h"
+#include "connection.h"
+#include "robomaster.h"
+
+void
+set_wheel_speed (
+		Client session,
+		int16_t w1,
+		int16_t w2,
+		int16_t w3,
+		int16_t w4 ) {
+    union Request req = {0};
+    req.wheel.wheel_speed[0] = w1;
+    req.wheel.wheel_speed[1] = w2;
+    req.wheel.wheel_speed[2] = w3;
+    req.wheel.wheel_speed[3] = w4;
+    req_finalize(session, 0x3F, SET_WHEEL_SPEED_CMDID, sizeof(struct SetWheelSpeedReq), &req);
+    req_send(session->connection, &req, sizeof(struct SetWheelSpeedReq));
+}
diff --git a/src/robomaster.c b/src/robomaster.c
new file mode 100644
index 0000000..743921a
--- /dev/null
+++ b/src/robomaster.c
@@ -0,0 +1,65 @@
+#include "robomaster.h"
+
+#include "client.h"
+#include "message.h"
+#include "connection.h"
+
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/select.h>
+#include <netinet/in.h>
+#include <string.h>
+#include <stdio.h>
+
+Client client_new() {
+    struct Client* client = malloc(sizeof(struct Client));
+    memset(client, 0, sizeof(struct Client));
+    // TODO: Make this configurable
+    client->hostbyte = host2byte(DEFAULT_CLIENT_HOST, DEFAULT_CLIENT_INDEX);
+    return client;
+}
+
+void client_connect(Client client) {
+    client->connection = connection_new();
+
+    set_sdk_connection(client, CONNECTION_WIFI_AP, 0, 10010);
+}
+
+void poll_message(Client client, union Message* resp) {
+
+    // Poll for messages
+    static struct timeval timeout = {-1, 0};
+    fd_set read_fds;
+    FD_ZERO(&read_fds);
+    FD_SET(client->connection->sockfd, &read_fds);
+    int result = select(client->connection->sockfd + 1, &read_fds, NULL, NULL, &timeout);
+
+    // Check for socket polling errors
+    if(result < 0) {
+        perror("message polling failed");
+	exit(EXIT_FAILURE);
+    }
+
+    // Skip if nothing was received yet
+    // TODO: Make a static "empty" message or something
+    if (result == 0) {
+        return;
+    }
+
+    // Read a message from the socket
+    // TODO: Use union to make all messages same size
+    int recvb = recvfrom(client->connection->sockfd, resp, sizeof(union Message), 0, (struct sockaddr*)&client->connection->remote_addr, &client->connection->addrlen);
+
+    // Check for socket read errors
+    if(recvb < 0) {
+        perror("reading socket failed");
+	exit(EXIT_FAILURE);
+    }
+
+    // Check for message errors
+    if(message_validate(resp)) {
+        perror("invalid message");
+	exit(EXIT_FAILURE);
+    }
+
+}
diff --git a/src/robomastersh.c b/src/robomastersh.c
index 5c35d6f..593fbea 100644
--- a/src/robomastersh.c
+++ b/src/robomastersh.c
@@ -1,50 +1,9 @@
 #include "robomaster.h"
 
-#include <arpa/inet.h>
-#include <stdio.h>
-#include <assert.h>
-
-uint8_t buffer[1024] = {0};
-uint8_t recvbuff[1024] = {0};
-
 int main(int argc, char* argv[])
 {
-    Client session = session_new(buffer, sizeof(buffer));
-    struct SetSdkConnectionReq req = {0};
-    req.control = 0;
-    req.host = 0;
-    req.connection = CONNECTION_WIFI_AP;
-    req.protocol = 0;
-    req.ip_address = 0;
-    req.port = 10010;
-    const Message msg = set_sdk_connection_req_new(session, &req);
-
-    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
-    struct sockaddr_in dest_addr = {0};
-    socklen_t addrlen = sizeof(dest_addr);
-    dest_addr.sin_family = AF_INET;
-    dest_addr.sin_port = htons(30030);
-    dest_addr.sin_addr.s_addr = inet_addr("192.168.2.1");
-    sendto(sockfd, buffer, session_size(session), 0, (struct sockaddr*)&dest_addr, addrlen);
-
-    int recvb = recvfrom(sockfd, &recvbuff, sizeof(recvbuff), 0, (struct sockaddr*)&dest_addr, &addrlen);
-    struct Message* resp = (struct Message*)recvbuff;
-
-    // check length
-    uint16_t resplen = (recvbuff[2] & 0x3) * 0xFF + recvbuff[1];
-    if(recvb != resplen)
-        fprintf(stderr, "expected length %d got %d", recvb, resplen);
-
-    // check header crc
-    uint8_t expected_crc8 = crc8(resp, 3);
-    if(resp->header.crc != expected_crc8)
-        fprintf(stderr, "expected crc8 %d got %d", resp->header.crc, expected_crc8);
-
-    // check footer crc
-    uint16_t expected_crc16 = crc16(recvbuff, recvb - 2);
-    uint16_t actual_crc16 = *(uint16_t*)(recvbuff + recvb - 2);
-    if(actual_crc16 != expected_crc16)
-        fprintf(stderr, "expected crc16 %d got %d", actual_crc16, expected_crc16);
+    Client client = client_new();
+    client_connect(client);
 
     return 0;
 }
diff --git a/src/sdk_connection.h b/src/sdk_connection.h
deleted file mode 100644
index 04b1401..0000000
--- a/src/sdk_connection.h
+++ /dev/null
@@ -1,47 +0,0 @@
-#pragma once
-
-#include "robomaster.h"
-#include "message.h"
-
-static const uint8_t SET_SDK_CONNECTION_CMDID = 0xD4;
-
-enum CONNECTION {
-    CONNECTION_WIFI_AP = 0,
-    CONNECTION_WIFI_STA = 1,
-    CONNECTION_USB_RNDIS = 2
-};
-
-struct PACKED SetSdkConnectionReq {
-    uint8_t control;
-    uint8_t host;
-    uint8_t connection;
-    uint8_t protocol;
-    uint32_t ip_address;
-    uint16_t port;
-};
-
-struct PACKED SetSdkConnectionResp {
-    uint8_t retcode;
-    uint8_t state;
-    uint32_t config_ip;
-};
-
-static
-inline
-const Message
-set_sdk_connection_new(
-		Client session,
-		enum CONNECTION connection_type,
-		uint32_t ip_address,
-		uint16_t port ) {
-
-    const struct SetSdkConnectionReq msg = {
-        0,
-	session->hostbyte,
-	connection_type,
-	0,
-	ip_address,
-	port
-    };
-    return message_new(session, 0x3F, SET_SDK_CONNECTION_CMDID, sizeof(msg), &msg);
-}
diff --git a/src/sdk_mode.h b/src/sdk_mode.h
deleted file mode 100644
index 6ddf932..0000000
--- a/src/sdk_mode.h
+++ /dev/null
@@ -1,24 +0,0 @@
-#pragma once
-
-#include "robomaster.h"
-#include "message.h"
-
-static const uint8_t SET_SDK_MODE_CMDID = 0xd1;
-
-struct PACKED SetSdkModeReq {
-    uint8_t enable;
-};
-
-struct PACKED SetSdkModeResp {
-    uint8_t retcode;
-};
-
-static
-inline
-const Message
-set_sdk_mode_new(
-		Client session,
-		bool enable ) {
-    const struct SetSdkModeReq msg = { enable };
-    return message_new(session, 0x3F, SET_SDK_MODE_CMDID, sizeof(msg), &msg);
-}
diff --git a/src/set_wheel_speed.h b/src/set_wheel_speed.h
deleted file mode 100644
index a106a70..0000000
--- a/src/set_wheel_speed.h
+++ /dev/null
@@ -1,24 +0,0 @@
-#pragma once
-
-#include "robomaster.h"
-#include "message.h"
-
-static const uint8_t SET_WHEEL_SPEED_CMDID = 0x20;
-
-struct PACKED SetWheelSpeedReq
-{
-    int16_t wheel_speed[4];
-};
-
-static
-inline
-const Message
-set_wheel_speed_new (
-		Client session,
-		int16_t w1,
-		int16_t w2,
-		int16_t w3,
-		int16_t w4 ) {
-    const struct SetWheelSpeedReq msg = { {w1, w2, w3, w4} };
-    return message_new(session, 0x3F, SET_WHEEL_SPEED_CMDID, sizeof(msg), &msg);
-}