CASIO 9750G User Manual

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Connecting the PICAXE 08M and PICAXE 18X

to the Casio 9750G Plus graphics calculator

Introduction to Casio BASIC

Compiled from various web resources

July 2008 © Michael Fenton

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Casio BASIC

PART 1: Creating a Program

To create a new program press then locate the program icon, press , press to create a new program. You will then be asked to enter a name for

your program, also you may create a password at this time (WARNING: if you put a password on your program you will not be able to use the debugger).

PART 2: Variable Basics

A variable is something which holds a value. The most commonly used are the

letters A~Z and r,_. There are others, but they are not covered in this section. To

store a value into a variable you must use the key, like this:

CODE

1->A // Assigns 1 to A

It should look like this:

CODE

1->A~D // Assigns 1 to A B C & D

Variables are the most important aspect of programming.

PART 3: Basic Loops

Loops are used to repeat blocks of code. There are several types of loops in Casio

BASIC: Goto/Lbl, Do/lpWhle, For/Next, and While/WhileEnd. Here is an example of

a Goto/Lbl loop:

CODE

1->A //Assigns 1 to A

Lbl 1

A+1->A //Adds 1 to the variable A and stores new value

Goto 1 //Returns to Lbl 1

This loop will execute infinitely, Adding 1 to A each time (actually it will stop when

the value of A is greater than 99*10^99 because you will get a mem error).

Here is an example of a For loop; note that it does not take as many lines:

CODE

For 1->A to 100 Step 1

//this loop assigns 1 to A then adds 1 to A until it equals 100

Next //Goes back to the start of the loop, adds the step to the

variable.

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Anything between the For and next statement will be executed until the expression

evaluates true (A equals 100). By changing the value of Step you can change how

much A is incremented by.

The While loop checks to see if the expression is true then executes the code. After

the code has been executed it returns to the top, checks the expression, and if it is

false jumps out of the loop and continues with executing the program. This is an

example of a While loop.

CODE

1->A

While 1=1 //1 always equals 1 so the expression always evaluates to

True

A+1->A

WhileEnd

Since the while loop evaluates the expression before executing the code it is

possible that if the expression is false before loop begins (ex: 1=2) then the loop

will never occur, it will just skip right over the code and continue with the program.

Unlike a while loop a Do/LpWhle loop will always execute at least once since it

evaluates the expression after the code has been executed. A Do/LpWhle loop looks

like this.

CODE

1->A

Do //Start of the Do/LpWhle loop

A+1->A

LpWhle A<100 //Loops while A is less than 100

PART 4: Selection Statements

Selection Statements are used to make programs have differing outcomes, instead

to executing the same way every time they are run. A selection statement checks

an expression, sees if it is True or False, then if True executes the rest of the

statement otherwise it skips to below the statement and continues with execution.

There are two types of selection statements on the calculator. They are the If/Else

statement and the => arrow.

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An If/Else statement works like this

CODE

1->A

If A=1 //expression to be evaluated

Then “HI” //result if expression is true

“HOW ARE YOU”

Else “BYE” //result if expression is false

“SEE YOU LATER”

If End //end of statement

Result:

Since A is 1 the statement evaluates to true, therefore

QUOTE (Program Output)

HOW ARE YOU

is printed. If you replaced the first line with 0->A then the if statement would

evaluate to False, and

QUOTE (Program output)

BYE

SEE YOU LATER

would be printed.

An If statement can contain many different things, and can be many lines long,

they are the keystone to making a game, and before going on you should feel

comfortable using them.

The => arrow is also very useful, it is a single line selection statement that takes

up less space but can do less than a normal if/else.

This is the same code as above, except using the => arrow instead of the If

statement.

CODE

1->A

A=1=>”HI”

A=1=>“HOW ARE YOU”

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A<>1=>”BYE” // <> means not equal to

A<>1=>”SEE YOU LATER”

In general, the best time to use a if statement is when you have at least two lines of code to be put inside, otherwise use the => arrow.

PART 5: Advanced Loops

Nesting is when you take one loop and put it inside another. Here is an example:

CODE

0->C

For 1->A To 10 //Step can be omitted instead of using Step 1

For 1->B To 10

A+B+C->C

C // the represents the output sign, it displays whatever is

before it and Pauses until [EXE] is pressed.

By executing this code you will get this output:

QUOTE (Program Output)

1100 //caused by

Now we will go through the code and look at what each line does.

Line 1: 0->C

Assigns the value 0 to the variable C

Line 2: For 1->A To 10

Tells the program that you will be looping until A is equal to 10, adding 1 with each

loop.

Line 3: For 1->B To 10

Tells the program that you will be looping until B is equal to 10, adding 1 with each

loop.

Line 4: A+B+C->C

The current value in A will be added to the current value of B, that value is then

added to the current value of C and then assigned to C.

Line 5: Next

Goes to line 3.

Line 6: Next

Goes to line 2.

Line 7: C

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Displays the final value of C.

As you can see, the second loop executes completely for each iteration (loop) of the

first loop.

Nesting also applies to selection statements, you can nest if or => inside each

other as needed.

Example:

CODE

A<1=>A>0=>”HI”

If A<1

Then if A>0

Then “HI”

End If

Part 6: Logical Operators

As you have just seen, there are times when you will want more than one condition

in a selection or loop, you can nest the statements or you can use a logical

operator: AND OR, NOT.

AND and OR are operators which can be used in selection statements to specify

additional conditions, therefore the code above could be written:

CODE

A<1 and A>0=>”HI”

Instead of:

CODE

A<1=>A>0=>”HI”

The OR operator allows you to specify alternate conditions which are evaluated

independently and if any are true then the entire statement is considered true. This

means you can do this:

CODE

If A=1 Or B=1

Then “TRUE”

End If

When this executes it will print TRUE if A or B equals 1.

The NOT operator can also be used in selection statements, though it is not used

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nearly as often. NOT returns False if the statement is true (or 1) and True if the

statement is False (or 0) so:

CODE

If Not (A=1)

Then “TRUE”

End If

This will print true if A is any number but 1. In this case the Not statement is used as an <> (not equal to) statement, but it has other uses. We will cover more on this later.

Part 7: Input Basics

You might want to get information from the user. The simplest way to get input from the user is to use the ? command.

Syntax: ?->(Variable) Description: this command causes a ? to appear on the screen, execution pauses

until the user enters data and hits , then the data is put into the variable. This is a good way to ask yes or no questions, with the user having to enter 1 for yes and 0 for no.

Another way you can use the ? command is to put a prompt before it: “Continue (1=YES 0=NO)”?->C This causes the text to be displayed with a ? after it and waits for data.

Part 8: Key Input

Sometimes you will want to know what key the user is pressing, to do this you

must use the Getkey command.

Syntax: Getkey->(variable) or if Getkey=(key number)

Description: Getkey returns a different value for each key pressed, if no key is

pressed then it returns 0, here is a simple program used to display the value of a

key.

CODE

Lbl 1

Locate 1,1,Getkey

Goto 1

The only key which does not return a value is AC/On.

Part 9: Advanced Loops

A simple loop:

CODE

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While A<>B

WhileEnd

A nested loop:

CODE

While A<>B

LpWhile A=B

WhileEnd

A nested loop is just a loop inside of a loop, just like a nested if. what most people

have trouble with is the execution of nested loops, if you have programming

experience then you will all ready know this but if your new to field take a look at

the sample below:

CODE

Lbl 1

1->A

1->B

1->C //counter var

1->D //counter var

A+B->A

While D<=5 //loops 5 times

B+A->B

Isz D

WhileEnd

1->D

Isz C

LpWhile C<3 //loops 3 times

A+B

Go through this program and see if you can figure out what the output will be, then

look below for the answer.

if you did not get 610 as the output then you made a common mistake. You do not

understand one of the basics of nested loops:

QUOTE

PRIMARY RULE: an inner loop executes fully for each interation (loop) of an outer loop

The break statement: Break terminates execution of a loop and resumes normal

program flow at the end of that loop.

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CODE

While A=A //endless loop

Isz A

Break

"THIS ISN'T SHOWN, IT ISN'T EVEN LOOKED AT BY THE PROGRAM"

"NEITHER IS THIS"

WhileEnd

"ESCAPE FROM THE LOOP" //Break goes to here

now we will look at how Break works in nested loops

CODE

While A<>B

Break

LpWhile A=A

//Break goes to here

WhileEnd //loops like normal

As you can see, Break only exits the current loop, and when that loop comes around again and if Break isn't executed (if it’s in an If statement) then the loop does not terminate and continues like normal. Get it?

CASIO Basic examples

Example 1:

====SUMDICE===

Lbl 1 “First number”? -> A If Int (A) A Then Goto 1 IfEnd “Second number”? -> B AxB Goto 1

How It Works We have told the program to take the integer of A and test it against the actual value of A. If these two don’t equal, then obviously A is not an integer. The next part of the statement is the Then command, since we said, ‘if they don’t equal, then go to label 1’. If A is an integer, the program will ignore the Then statement.

The ⇑ symbol is in the PRGM (SHIFT VARS) menu and it means ‘stop the program and display this result’

Example 2: Storing data in a list

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The usefulness of the results in the simulation is limited because the outcomes are not stored anywhere, since the variable S is always changing during each loop. This is why it is a good idea to store data in lists (sometimes called arrays), where it can then be analysed later. This is the purpose of this lesson.

In order to store the data in a list, we must first set the dimensions of the list. This

means telling the calculator how many elements there are to be stored. Since we are using the variable C as the number of simulations, this will be used as the dimensions of list 1. Lets set C equal to 5….

C -> 5

Then add the line The commands Dim and List are found in the LIST menu, which is in the OPTN menu. Press OPTN, followed by LIST (F1). Just about any action that relates to lists will be found in this menu.

C -> Dim List 1

A Bit of Extra Help

Enter RUN mode from the Main Menu. Enter this line and press EXE.

C -> Dim List 1

This line says that I want to have 5 ‘empty’ elements in List 1 (they are in fact filled with the value of 0). Press MENU and then enter STAT mode. You will see that there are 5 ‘empty’ elements in List 1.

You will notice that this command has created 5 ‘empty’ elements in list 1. As a rule, whenever you want data to be stored in a list (during the execution of a program), you must first create empty elements using the command described above. This is, if you tried to enter data in position 6, you would receive an error message.

CODE

For 1 -> Z to C Int (6Ran#)+1 -> M Int (6Ran#)+1 -> N M + N -> S S -> List 1[Z] Next

How It Works

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When the program first comes to the For statement, it will set Z to 1 and go through and execute everything on the way to the Next command. This means it will get to

-> List 1[Z]

and send the value of S (which has been set as M+N) to List 1, row Z, which at the moment is 1. After this, the program will move on to the next line, which is the Next command in this case. Once it gets to the Next command, the program will go back to the For command and do it again, except Z will now be set to 2. So then the new value of S will be sent to List 1, row Z, which is now 2. This will continue over and over again until Z=C. Notice how having the command within the For statement utilises the way Z increases by 1 each time.

The maximum number of elements that this particular calculator can

S -> List 1[Z]

handle in 255.

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PICAXE circuits

1. Electrical communications:

TTL-level (High=5V and Low=0V), asynchronous serial half-duplex communication, connects to a PC´s RS-232 COM-port with a MAX232 or equivalent level-converter circuit.

• Baud-rate: 9600 bps

• Parity: none

• Byte-size: 8 bits

• Stop-bits: FROM Casio: 2 bits TO Casio: 1 bit

The Casio-plug is a standard 2.5mm stereo jack with the following pindesignations:

• Sleeve Ground

• Ring Data to Casio

• Tip Data from Casio

2. Casio to Casio cross-over cable

2.5 mm stereo plug 2.5 mm stereo plug

3. Casio to PC RS232 interface

2.5 mm stereo plug from Casio connected to a PC D9 female plug.

BC547C can substitute for BC337 NPN transistors.

LED’s in series with Rx and TX can indicate communication to and from PC

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4. Casio to Picaxe

Place small signal diode 1N4148 (bar toward Picaxe) in series with output TO Casio inside the 3.5mm stereo plug.

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6. Casio 9750G Plus Code: RECEIVE picaxe data into a List:

255 -> Dim List 1 255 -> Dim List 2 1 -> B Lbl 1 "Get readings (1 = YES)"? -> A A = 1 => Goto 2 Goto 1 Lbl 2 Receive (R)

// R x 0.123 -> A convert to degree celcius or whatever units

Getkey -> C If C 1 47 Then Goto 3 IfEnd If B < 256 Then B-1 -> List1[B] A -> List2[B] B+1 -> B IfEnd Lbl 3 ClrText Locate 1,1, B-1 Locate 6,1, A If B = 256 Then Locate 1,2, “LIST FULL!” IfEnd

Goto 2

How It Works

• List 1 and List 2 is created with 255 spaces (rows) assigned to them

• Once the user inputs “1” the Casio displays data values from the PICAXE but

• From the MENU select STATs (2 on main menu)

• press F1 (GRPH) then F6 (SET) to set up the graphing options.

• Go down to graph type and press F6 to get to other graph types then choose

•

The data collected can be transformed to temperature, etc by adding line in blue above (remove // remark symbol)

Students can try to fit a

only puts them into LIST 2 (y axis) if the EXIT button is pressed. List 1 is for plotting the x axis 0 – 255 time intervals.

box (for a box and whisker). Press EXIT back to the list (you should be able to see your data in the list), press F1 to get a box and whisker graph, good for working out mean, upper quartile and range.

or other curve and explain

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7. Casio 9750G Plus Code: SEND keystrokes to picaxe ypod to control CASI

Lbl 1 Getkey -> A

If A > Then Int((A-26); 2.5 +0.2) -> A // ; means divided by Send (A) IfEnd Goto 1

How It Works

•

CASI has an 08M slave that listens for Casio keystrokes

•

CASI 08M interrupts a 14M master with the keystroke

•

CASI turns on a L293D motor controller chip to move CASI in the appropriate direction

•

SRF05 sonar range finder prevents obstacle collisions

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8. Casio 9750G packet encoding:

Modified from article by Erik Grindheim, August ~ October 2001

There are four different types of data packets in use to transfer variables, in addition to the single-byte packets. This section describes the structure of these packets in detail:

Request packet:

Byte no (1-50) ASCII

1-4 :REQ $3A $52 $45 $51 5 6-7 VM (Variable)

8-11 12 A-Z / r / è (The name of the Variable:)

13-49 50

PC (Picture) LT (List) MT (Matrix)

$00 $56 $4D <-- This is the bytes we want...

$50 $43 ( Byte no 12-49 below is based ) $4C $54 ( on Variable transfers, VM. ) $4D $54 ( ) all $FF

$41 - $5A / $CD / $CE all $FF Checksum = $01 + not((sum bytes 1-49)- $3A)

Variable description packet:

Byte no (1-50) ASCII

1-4 :VAL $3A $56 $41 $4C 5 6-7 VM $56 $4D 8 9

10 11 12 A-Z / r / è 13-19 20-27 Variable 28 C or R $43 or $52

29 30-49 50

$00

$00 if the variable is reset/unused: $00 ** if variable is in use (normal): $01 $00 the same value as byte no 9: $00 or $01

all $FF $56 $61 $72 $69 $61 $62 $6C $65

(If the variable has an imaginary part: C-complex. Otherwise: R-real) $0A all $FF Checksum = $01 + not((sum bytes 1-49)- $3A) **note: If bytes 9 and 11 has the HEXvalue 00 this means that the variable has not been used after last "Alpha Memory" reset. Then no Value packet will be transmitted at all. After this packet comes the End packet.

HEX ($)

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Variable packet, Real numbers:

Byte no (1-50)

1 : $3A 2-5 6 7-13 14

The smallest value the Casio accepts is ± 1.00000000000000 × 10 The greatest number the Casio accepts is ± 9.99999999999999 × 10 Zero is stored as + 0.00000000000000 × 10

Or, at a general form: ± I.decimals × 10

In the Value packet, byte no. 6 is containing the integer part I, always from $01 to $09 (except if the variable value is exactly 0,0…). Bytes no. 7 to 13 contain the 14 decimals represented as BCD data. The exponent EE is represented in byte no. 15 and bit 0 of the SignInfoByte (byte no. 14). The sign indicating whether the value is negative or positive is held in bits 6 and 4 of the SignInfoByte.

ASCII

HEX ($)

$00 $01 $00 $01 $00-$09 (BCD 0 and BCD 0-9 (integer part)) $00-$99 (BCD for 14 digits (decimal part)) SignInfoByte. Bit set if...:

bit 7 - Variable has an imaginary part bit 6 & 4 - Value (real part) is negative bit 0 - Absolute value of (real part of) value is 1,0... or more bits 1, 2, 3 and 5 are always 0 / Low Exponent, 00-99 Exp.: Byte: +99 99 \ +01 01 -} byte 14 bit 0 = 1 (High) ** 00 00 /

-01 99 \

-02 98 -} byte 14 bit 0 = 0 (Low)

-99 01 / Checksum = $01 + not((sum bytes 1-15)- $3A) **note: If the variable is (exactly) 0,0 then the exponent is 00 (instead of minus infinite) but this bit (bit 0 in byte

14) is still low because variable value is less than 1.

-99

+99

+EE

+00

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Variable packet, Complex numbers:

Byte no (1-50)

1-15

17-23 24

End packet (aways the same!):

Byte no (1-50)

1-4 :END $3A $45 $4E $44

5-49

50 V $56 (checksum, always the same value for

Checksum calculation:

As an example let’s show how the checksum of the End packet is calculated. This value will always remain the same since nothing in this packet changes from time to time. First we add all the previous 49 bytes. This gives us a sum of $E4 (the excess carry digits are thrown away). Then we subtract $3A and the result is $AA. We invert it (=$55) and add $01. The result is $56, which is the checksum-byte; byte no. 50.

ASCII

HEX ($)

Equal to bytes 1-15 in the 16 bytes long Value packet for real numbers. These bytes only describe the real part of the variable, while the next 10 bytes describe the imaginary part of the complex number: $00-$09 (BCD 0 and BCD 0-9 (integer part))

$00-$99 (BCD for 14 digits (decimal part)) SignInfoByte. Bit set if...:

bit 7 - Always set to 1 (imaginary) bit 6&4 - Value (img. part) is negative bit 0 - Absolute value of (img. part of) value is 1,0... or more bits 1, 2, 3 and 5 are always 0 / Low Exponent for the imaginary part; 00-99 Exp.: Byte: +99 99 \ +01 01 -} byte 24 bit 0 = 1 (High) 00 00 /

-01 99 \

-02 98 -} byte 24 bit 0 = 0 (Low)

-99 01 / Checksum = $01 + not((sum bytes 1-25)- $3A)

HEX ($)

all $FF

all End packets no matter what other packets have been sent)

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$15

$13

$06

9. Casio 9750G RECEIVE() sequence / protocol

• When the command is issued the Casio sends an “attention request” byte, $15

• The external device must reply with a “device present” byte, $13 within 0.5 ~ 1 second or a Com ERROR message is displayed

• The Casio sends a Request packet which consist of 50 bytes.

• The external device receives this and confirms with one byte, $06.

• The Casio confirms that it’s ready for a Variable-description packet with $06

• The external device sends a Variable-description packet consisting of 50

bytes. Byte 12 in this packet (variable name) seems to be totally ignored by the Casio, as the variable is stored under the name indicated in the Request packet anyway. Still it’s recommended to send back the same name/byte as received in the Request packet byte 12.

• The Casio confirms that it’s ready (for a Value packet or an End packet, depending on byte 9 and 11 in the previous packet) with $06

• A Value packet is then sent from the external device. It is still consisting of either 16 or 26 bytes, depending on whether the variable also contains an imaginary part (complex number) or not. If the variable is empty this packet is not sent at all (length: 0 bytes). This means that the actual “Alpha Memory” variable in the Casio is deleted. This will free 10 (real) or 20 (complex) bytes of memory in the Casio. In calculations the deleted variable’s value equals zero (0).

• If a Value packet was sent then the Casio confirms (as usual) with $06 (if the variable is empty there is no Value packet, and this byte is not sent either.)

• To close the communication cycle the external device sends an End packet of 50 bytes. The end packet is always the same; none of the bytes change their value.

Casio PICAXE

Request packet

$06

Variable description packet

Value packet

End packet

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$15

$13

$06

10. Casio 9750G SEND() sequence / protocol

• When the command is issued the Casio sends an “attention request” byte, $15

• The external device must reply with a “device present” byte, $13 within 0.5 ~ 1 second or a Com ERROR message is displayed

• The Casio starts to send the Variable-description packet, which consists of 50 bytes.

• The external device receives this and confirms with $06.

• The Casio sends its Value packet, consisting of either 16 or 26 bytes. Packet

length depends on whether the variable also contains an imaginary part (complex number) or not. If the variable has never been assigned a value since the last reset of “Alpha Memory” this packet will not be sent at all.

• The external device receives this packet and confirms with $06. (If an empty variable is sent, then there is no Value packet, and this byte is not sent either.)

• To close the communication cycle the Casio sends an End packet of 50 bytes. The end packet is always the same; none of the bytes change their value.

Casio PICAXE

Variable description packet

Value packet

End packet

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CASIO 9750G User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual