The image above represents the Pin assignments window. Once all the pins and switches have been assigned, minimize the constraint editor, plug in the JTAG download cable into the parallel port of the laptop, connect the power supply to the development board and run ' Fit Design ' (found on the right navigator window of the ispDesignExpert) by double clicking on it. Once the ' Fit Design ' has completed, a JEDEC file by the name of ' statemach.jed ' was created in the same directory as the "statemach.abl'.

The next step involves downloading the design on to the M4-64/32 CPLD on the development board. In order to do this, run the ' ispVM System '. With the power supply connected to the development board and the JTAG download cable connected to the laptop, click on ' Scan ' in the toolbar to automatically detect the CPLD on the development board. Once the M4-64/32 appears on the device list, double click on it to get the device information dialog box. The image below is a capture from the ispVM System:

The Program:

The program describes a six state machine. The possible states are namely U22A, U22B, U22C, U22D, U22E, and U22F.

The first part of the program involves the declaration of the inputs, outputs and nodes. The pin types for the outputs are also declared; where 'com' is for combinational output and 'reg' is for registered output).
The second part of the program lists and defines the possible states. For example:

SEG10n0 = [U22A, U22B, U22C, U22D, U22E, U22F, U22G];

S0 = [1, 0, 0, 0, 0, 0, 0];

means that the S0 state is such that only the U22A pin is active (1) while all the other pins are inactive(0).

The 'Equations' section describes the response of the circuit to inputs. The statement 'running_light.CLK = SelClk;' acts as a counter and allows us to adjust the speed of the outputs through the on-board jumper connections. The second statement 'running_light.AR = (SWINP = =4);) allows us to reset the six state machine to the U22A state and restart the loop. 'SWINP == 4' represents the switch input set [1,0,0] (binary representation of 4); so the machine is reset when Switch 1 is pressed.

The 'State_diagram' section controls the flow of the program. It lists all the possible states and the subsequent arguments of the machine. Typical statements are :

state Seg_A : SEG10n0 = S0;

If S0 then Seg_B;

state Seg_B : SEG10n0 = S1;

The keyword state_diagram indicates the beginning of a state machine description.

The syntax for State_diagram is as follows:

State_diagram state_reg

STATE state_value : [equation;]

[equation;]

...

trans_stmt ; ...

The keyword state_diagram indicates the beginning of a state machine description.

Here, state_reg is the identifier to define the signal, which will determine the state of the machine. state_value is either an expression or a value or a symbol for the current state. trans_stmt consists of statements like 'if-then-else', case or goto to define the next state.

The first statement assigns the state S0 to Seg_A . That is U22 is at the following state:
[1, 0, 0, 0, 0, 0, 0]

(U22A - ON, U22B - OFF, U22C - OFF, U22D - OFF, U22E - OFF, U22F - OFF, U22G - OFF)

The second statement (If S0 then Seg_B) is an argument that implies that if the state machine is at state S0, the next state is that for Seg_B (i.e. S1). The same arguments apply to the rest of the program.

Observations:

-The result of the program was the following loop:

(Using the same SSD identification used in Lab Report 2)

U22A to U22B to U22C to U22D to U22E to U22F to U22A...

Modifications to the program:
Deriving from the previous rolling ball program we can create a program which rolls a ball on the sides of all the 4 seven-segment displays or even a program which rolls several balls, like a snake on the 4 seven-segment displays.
This program rolls the ball on the edges of the 7-segments:

MODULE StateMachine

TITLE 'State machine example'

" Inputs from evaluationkit
!SW1 pin;
!SW2 pin;
!SW3 pin;

" fourth SevSeg from left
!U22A pin istype 'com';
!U22B pin istype 'com';
!U22C pin istype 'com';
!U22D pin istype 'com';
!U22E pin istype 'com';
!U22F pin istype 'com';
!U22G pin istype 'com';
!U23A pin istype 'com';
!U23D pin istype 'com';
!U24A pin istype 'com';
!U24D pin istype 'com';
!U24E pin istype 'com';
!U24F pin istype 'com';
!U26A pin istype 'com';
!U26D pin istype 'com';

" Clock inputs
SelClk pin;

Q1..Q12 node istype 'reg';

" Sets for inputsignals
SWINP = [SW1, SW2, SW3];

" Sets for output signals
ON = [Q1..Q12];
SEGs = [U22A, U22B, U22C, U22D, U26D, U23D, U24D, U24E, U24F, U24A, U23A];

Equations

ON.CLK = SelClk; " Clock for counter
ON.AR = (SWINP == 4)#(ON == 1); " Reset for counter

When ON == 0 then ON := 2;
else ON := ON + ON;

SEGs = [Q1..Q11];
U26A = (ON == 0);

END

You can download the moving snake program from here: snakestate.abl. It shows how to move four lights on the SSDs.