Modular Programming

1. Modular Programming Where the rubber meets the Code

2. The three uses of static

3. Encapsulation Groups together the data and the functions that operate on the data Publishes an interface to the rest of the code Hides the details of the implementation

4. Encapsulation

5. What goes into a header file?

6. What shouldn’t be in a header file?

7. Where do you #include the header file?

9. Module Design by Interface Specification View: The module provides Services to the rest of the code Design Activities: Specify the Services Describe Functionality Name the Services Design the implementation

10. Application Programming Interfaces (API) for the ME218c Master modules • Module: Communications to UI on PC • To avoid hanging up the master during the transmission or reception of messages, this module should implement buffered, interrupt driven transmit and receive. The communications routines for this module will need to be interrupt driven because the UI may send its message at any time. • Char InitializeUICommunications(void); • Do whatever hardware and software initialization necessary to prepare for communications with the UI on SC1. • Void TellUINewUserReady(void); • Should send the message to the UI that a new iButton has been inserted and read. • Unsigned char IsNameReady(void); • Should check to see if a new name is ready from the UI. Return TRUE if a new name is ready, FALSE otherwise. • Unsigned char GetNewName( unsigned char NameSpace[]) • Should copy the name gotten from the UI into the array NameSpace. The copy operation should copy no more than 16 characters, including the terminating NULL. Should return TRUE if there was a new name ready, FALSE otherwise. A Real Example

11. Design the interfaces to modules for Driving the platform Gathering sensor data Produce: Public interface specification What are the details that are being hidden?

12. Mike, Ian, and James // mike, james, and ian // cmpe 118, spring 05 // these functions or for the motor and sensory control of our final project // motor direction defines #define forward 1 #define brake 0 #define backward -1 #define success 1 #define failure 0 // Motor control functions char wheel_left(char direction, char speed); char wheel_right(char direction, char speed); // given a direction and a speed between 0 and 10 it return 0 if failure // and 1 if successful. // The bot can coast by giving a direction of "forward" or "backward" with a speed of 0, // or it can brake by giving any speed with a direction of "brake".

13. // bump sensors char bump_sensors(void); // When called it will return a char where the upper four bits are always 0 then front left, front right, back right, back left. // line sensors char line_sensors(void); // when called it will return a char where the upper four bits are always 0 then forward left, // forward middle, forward right, and middle; // aiming sensors char aim_sensors(void); // when called it will return a char where the top six bits are zero left aiming photo transistor, // and right aiming photo transistor. // firing solenoid char firing(char); // when passed a 1 solenoid is open and it firing, when passed a 0 is closed. Will return 0 for // failure and 1 for success.

14. Thomas, Maria, and Oscar DRIVING void LeftMtrSpeed(uchar speed) void RightMtrSpeed(uchar speed) IR uchar getBroadIR() //Returns IR level for broad sensor uchar getAccurateIR() //Returns IR level for narrow sensor TAPE uchar checkTape() //Returns solid state for tape (could be boolean) TURRET uchar TurnLeft(uchar distance) // Returns status uchar TurnRight(uchar distance) // checks for homeswitch BUMPERS uchar getBumpers() //Returns which bumpers are pressed

15. John and Suraj #ifndef DROID_H #define DROID_H #include "util.h" // types         typedef enum { DIRECTION_LEFT, DIRECTION_RIGHT, DIRECTION_FORWARD, DIRECTION_BACKWARD } Direction; // functions /**      Makes the droid search for a target (tie fighter or death-star beacon) by slowly rotating and scanning in the direction specified.                 @param  a_dir   The direction in which to scan for a target.                 @return false when no target has been detected. */ boolean Droid_scan(Direction a_dir); /**       Makes the droid seek out its nearest target and orient itself such that it is facing the target. From here, the droid may proceed forward and engage the target.                 @return false when no target has been detected.       */ boolean Droid_seek(); /** Makes the droid engage its nearest target by driving forward, while dynamically adjusting its trajectory, until the droid is within point-blank firing range. Next, the droid fires a foam ball at the target.                 @return false when no target has been detected. */ boolean Droid_engage();

16. /** Rotates the droid, in the given direction, by the given number of steps.                 @param  a_dir   The direction in which the droid shall rotate.                 @param  a_numSteps      The number of discrete rotational steps the droid shall undertake in its rotation.                 @return false upon failure. */ boolean Droid_rotate(Direction a_dir, uint a_numSteps); /** Drives the droid, in the given direction, by the given number of steps.          @param  a_dir    The direction in which the droid shall drive.          @param  a_numSteps   The number of discrete translational steps the droid shall undertake in its translation.          @return false upon failure. */ boolean Droid_drive(Direction a_dir, uint a_numSteps); #endif

17. #ifndef SENSORS_H #define SENSORS_H #include "util.h" // types         typedef enum { SENSOR_PRECISION, SENSOR_LEFT, SENSOR_RIGHT, SENSOR_BUMP } Sensor; // functions /**    Initializes all sensors on the droid. */ void Sensors_init(); /**    Initializes the specified sensor on the droid.         @param  a_sensor        The sensor we wish to initialize.  */ void Sensors_initSensor(const Sensor a_sensor); /** Returns the quantified strength of the signal being sensed by the specified sensor.        @param  a_sensor  The sensor whose signal strength we wish to retrieve.*/ uint Sensors_getSensorStrength(const Sensor a_sensor); #endif

18. Mike, Ian, and Dev

20. Hierarchical State Machines (Harel Statecharts)

22. A Possible Top-Level State Diagram

23. Work out State Diagrams to Implement Finding Tape I

26. Implementing Hierarchical State Machines What do you need?

27. State Machine Function Template • If current state is state one • Execute During function for state one • If an event is active • If event is event one • Execute action function for state one : event one • Decide what the next state will be • Endif • If event is event two • Execute action function for state one : event two • Decide what the next state will be • Endif • Repeat the block above as required for each of the • possible events affecting this state. • If next state is different from current state • Execute exit function for state one • Execute entry function for new state • Modify state variable to reflect the new state • Endif • Endif • Return from state machine function

28. /****************************************************************************/**************************************************************************** Module d:\me218b\Lectures\Lecture 29\SMTemplate.c Description This is a template file for implementing state machines. Notes History When Who What/Why -------------- --- -------- 02/18/99 10:19 jec built template from MasterMachine.c 02/14/99 10:34 jec Began Coding ****************************************************************************/ /*----------------------------- Include Files -----------------------------*/ /* include header files for this state machine as well as any machines at the next lower level in the hierarchy that are sub-machines to this machine */ /*----------------------------- Module Defines ----------------------------*/ // define constants for the states and event for this machine /*---------------------------- Module Functions ---------------------------*/ /* prototypes for private functions for this machine, things like entry & exit functions. */ /*---------------------------- Module Variables ---------------------------*/ // everybody needs a state variable, you may need others as well static unsigned char CurrentState;

29. void RunStateMachine(unsigned char CurrentEvent ) { unsigned char NextState = CurrentState; switch ( CurrentState ) { case STATE_ONE : // If current state is state one DuringStateOne(); //Execute During function for state one if ( CurrentEvent != NO_EVENT ) //If an event is active { switch ( CurrentEvent) { case EVENT_ONE : //If event is event one // Execute action function for state one : event one NextState = STATE_TWO;//Decide what the next state will be break; } // If next state is different from current state if ( NextState != CurrentState) { // Execute exit function for current state // Execute entry function for new state CurrentState = NextState; //Modify state variable } } return;

30. /****************************************************************************/**************************************************************************** Function StartStateMachine Parameters None Returns None Description Does any required initialization for this state machine Notes Author J. Edward Carryer, 2/18/99, 10:38AM ****************************************************************************/ void StartStateMachine ( void ) { CurrentState = ENTRY_STATE; // call the (optional) entry function for the ENTRY_STATE // any other initialization necessary to re-start the state machine }