Reading from a USB joystick

alphy

I am writing the code for my school robot
I am very new to Parallax and was wondering how i read from out controller, a USB Joystick.
I am pretty sure that i have to use SERIn and SEROUT, but i could be wrong, any input would be greatly appreciated

Mike Green

You can't use a USB joystick directly with a Stamp. The only way you can use a USB device with a Stamp is with some kind of USB host controller like Parallax's Memory Stick Datalogger or Vinculum's VDIP1 or GHI Electronics' USBwiz.

You use SERIN and SEROUT with the USB host controller and the controller provides the proper signals for the USB device.

alphy

well im going to run it into a laptop then from the laptop to the BASIC Stamp Homework Board we are using.

Mike Green

That's a very different design. You normally would use SERIN / SEROUT to talk to the laptop. You'll have to develop a program on the laptop that will take the joystick information and send it to the Stamp. Keep in mind that the Stamp can only do one thing at a time. When it's not actually executing a SERIN statement, it will miss any data being transmitted from the PC. Usually, this is managed by having the Stamp ask the PC for the data, then waiting for an answer with a SERIN.

alphy

well, my teacher did it a few months ago but he was just instructed specifically and we ow added a motor and changed the design so we need to completely redo it


heres the code



' {$STAMP BS2}
' {$PBASIC 2.5}


'*** PIN Declarations *** 'Rename the Motors to better fit your ROV
MOTOR_0_A PIN 2 'Direction PIN A for motor0
MOTOR_0_B PIN 1 'Direction PIN B for motor0
MOTOR_0_E PIN 0 'Enable PIN for motor0 (use for PWM)

MOTOR_1_A PIN 5 'Direction PIN A for motor1
MOTOR_1_B PIN 4 'Direction PIN A for motor1
MOTOR_1_E PIN 3 'Enable PIN for motor0 (use for PWM)

MOTOR_2_A PIN 8 'Direction PIN A for motor2
MOTOR_2_B PIN 7 'Direction PIN A for motor2
MOTOR_2_E PIN 6 'Enable PIN for motor0 (use for PWM)

'SENSOR PIN 15 'Currently not used

'*** Asign Variables ***
motor0 VAR Byte 'Forward/Backward movement
motor1 VAR Byte 'Left/Right movement
motor2 VAR Byte 'Up/Down movement
y VAR Byte ' FW/BK dir
x VAR Byte ' L/R dir
z VAR Byte ' U/D
y_word VAR Word ' FW/BK dir
x_word VAR Word ' L/R dir



motor0_holder VAR Byte 'Forward/Backward Direction
motor1_holder VAR Byte 'Left/Right direction
motor2_holder VAR Byte 'Up/Down direction

a VAR Word
b VAR Word


repeat VAR Word 'repeat variable
freq VAR Word 'Frequency variable
freq_holder VAR Byte 'Frequency variable

results VAR Word 'store raw sensor input
sensor_data VAR Word 'store calibrated sample



Main:
freq_holder=255 'The begining frequency number
'Communication**************


HIGH 15
PAUSE 1
RCTIME 15,1 , results

sensor_data= -20 * results + 35048

sensor_data = sensor_data / 1000

'sensor_data = results

SEROUT 16, 16780, [noparse][[/noparse]sensor_data]

SERIN 16, 16780, [noparse][[/noparse]x] 'serial input=pin 1, 2400, motor0
SERIN 16, 16780, [noparse][[/noparse]y] 'serial input=pin 1, 2400, motor1
SERIN 16, 16780, [noparse][[/noparse]z] 'serial input=pin 1, 2400, motor2

'Sensor Goes Here***********



'sensor_data = 34
'SEROUT 16, 16780, [noparse][[/noparse]sensor_data]

'Motor Manipulation Here****

'DEBUG SDEC x ,CR
'DEBUG SDEC y , CR

IF x//2=0 THEN
x_Word=x/2
ELSE
x_Word=x/2 * -1
ENDIF

IF y//2=0 THEN
y_Word=y/2
ELSE
y_Word=y/2 * -1
ENDIF

a = x_word + y_word
b = y_word - x_word

'DEBUG SDEC x_word ,CR
'DEBUG SDEC y_word , CR

'DEBUG SDEC a , CR
'DEBUG SDEC b , CR

IF (a < 65409) AND (a > 32767) THEN
a = -127

ENDIF
IF (a > 127) AND (a < 32767) THEN
a=127
ENDIF

IF (b < 65409) AND (b > 32767) THEN
b= -127

ENDIF
IF (b > 127) AND (b < 32767) THEN
b=127
ENDIF
'DEBUG SDEC a , CR
'DEBUG SDEC b , CR

IF a > 32767 THEN 'test for odd number
a = ABS a
a = a * 2
a = a + 1 'makes it odd
ELSE
a = a * 2
ENDIF

IF b > 32767 THEN 'test for odd number
b = ABS b
b = b * 2
b = b + 1 'makes it odd
ELSE
b = b * 2
ENDIF


'DEBUG DEC a , CR
'DEBUG DEC b , CR




motor0_holder = a
motor1_holder = b
motor2_holder = z
'DIRECTION****************** '**** what does "//" do, use help to find out ****
IF motor0_holder//2=0 THEN 'determines if byte is even or odd for motor0
HIGH MOTOR_0_A
LOW MOTOR_0_B
ELSE
LOW MOTOR_0_A
HIGH MOTOR_0_B
ENDIF 'ends the statement

IF motor1_holder//2=0 THEN 'determines if byte is even or odd for motor1
HIGH MOTOR_1_A
LOW MOTOR_1_B
ELSE
LOW MOTOR_1_A
HIGH MOTOR_1_B
ENDIF 'ends statement

IF motor2_holder//2=0 THEN 'determines if byte is even or odd for motor2
HIGH MOTOR_2_A
LOW MOTOR_2_B
ELSE
LOW MOTOR_2_A
HIGH MOTOR_2_B
ENDIF 'ends statement



'SPEED******** 'This loop controls the PWM to the motor
repeat=5 'Sets variable 'repeat' at 1
Repeat_loop: 'Starts main loop
motor0=motor0_holder/10 'The next four lines are equations that takes the byte
motor1=motor1_holder/10 'sent down and divides it by 10, this lowers the
motor2=motor2_holder/10 'resolution but speeds up the loop. Adjust as needed.
freq=freq_holder/10

' The following 3 If test are used to set the Dead band of the
' controller (point the control must pass before it turns on).
' increase number to increase deadband.
IF motor0 > 3 THEN HIGH MOTOR_0_E 'This causes pin 3 to go high, turning on the motor
IF motor1 > 3 THEN HIGH MOTOR_1_E 'This causes pin 4 to go high, turning on the motor
IF motor2 > 3 THEN HIGH MOTOR_2_E 'This causes pin 5 to go high, turning on the motor

Frequency_Loop: 'Starts PWM loop
IF motor0 = 0 THEN 'determines if byte equals zero(0)
LOW MOTOR_0_E 'if byte is 0, set emable pin low, turning off the motor,
'if not 0, pin 3 remains high
ENDIF 'ends statement

IF motor1 = 0 THEN 'determines if byte equals zero(0)
LOW MOTOR_1_E 'if byte is 0, set emable pin low, turning off the motor,
'if not 0, pin 4 remains high
ENDIF 'ends statement

IF motor2 = 0 THEN 'determines if byte equals zero(0)
LOW MOTOR_2_E 'if byte is 0, set emable pin low, turning off the motor,
'if not 0, pin 5 remains high
ENDIF 'ends statement

motor0 = motor0 - 3 'subtracts varialbe by 1 within PWM loop
motor1 = motor1 - 3 'subtracts varialbe by 1 within PWM loop
motor2 = motor2 - 3 'subtracts varialbe by 1 within PWM loop
freq = freq - 3 'subtracts varialbe by 1 within PWM loop

IF freq <>0 THEN
GOTO Frequency_Loop 'as long as freq does not equal zero, the PWM loop repeats
ENDIF
repeat=repeat-1 'subtracts varialbe by 1 after freq=0 and PWM loop stops
IF repeat<> 0 THEN
GOTO Repeat_loop 'as long as repeat does not equal zero, the reapeat loop repeats
ENDIF
GOTO Main 'go back to run again
END 'Ends the program

Mike Green

Do you have a question now?

alphy

yea how would i do that? i dont know how to talk to the joystick

Mike Green

You'll have to talk to your teacher about what was done before.

You're asking for a simple answer for something that would take weeks to teach someone.
So much depends on what tools you have on hand like programming languages, compilers,
etc. You'd be much better off if you had some kind of joystick with just some switches and
variable resistors in it that a Stamp very easily could access directly. USB introduces a whole
other level of complexity.

crgwbr

I have to agree with mike here. USB is a very complex protocol working at speeds up to 480Mbps. The Stamp tops out at about 38.4 Kbps. The best chance you have is connecting it to the USBwiz chip. The FTDI Vinculum would also work, but from what I've heard, the USBwiz has better HID support.But even then, your going to have a lot of work to do for the interface. To be honest, I'm not really sure that one BS2 could do it; you may have to look into using a few SX's or a Prop. Long story short, you can't just plug in the RX and TX lines of the USB connector and expect it to work.

Anyway though, you should certainly try to get the project working.

Regards,
Craig

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alphy

The code up there they used before, and it worked. But i cannot figure out why, like what is port 16?

Mike Green

Port 16 is the programming port on the Stamp and is the serial port used by the DEBUG and DEBUGIN statements. The DEBUG statement is just a special case of the SEROUT statement with a fixed Baud and using port 16. There are some limitations with port 16. For example, anything sent to the Stamp is echoed back to the sender. Also, if the DTR handshake line is toggled off and on (like when the serial port is opened on the PC side), the Stamp will reset.

There must be some kind of program running on the PC that uses the joystick and communicates with the Stamp over the serial port.
Again, you need more information from your teacher.

alphy

Wow, taht was EXTREMELY helpful, thank you
now we just need to igure the rest of it out
is there a way to have parallax access a progrom?
i have a program that does that, just no idea how to use it.

Post Edited (alphy) : 3/29/2008 12:04:01 AM GMT

PJAllen

alphy stated...
i have a program that does that, just no idea how to use it.

And what program would that be?

alphy

a program that the people that run the competition gate us, its called MATE ROV control

Mike Green

You need to ask your teacher for help in finding the manual or documentation for the program.
I don't think we can help you here with that.

alphy

Thanks for all your help, you have been very helpful.