[Jnadke]

they easy way:

drive_L              var      byte
drive_R              var      byte
tempjoystick      var      byte


drive_R = (((2000 + p1_y + p1_x - 127) Min 2000 Max 2254) - 2000)
drive_L = (((2000 + p1_y - p1_x + 127) Min 2000 Max 2254) - 2000)
'single joystick drive code


if p4_sw_aux1 = 1 then
      tempdrive = drive_R
      drive_R = 254-drive_L
      drive_L = 254-tempjoystick
endif

Works like a charm. I used it last year on our robot.

Basically, you want to do the reverse code AFTER you figure out how fast you want each motor to go (assuming you're doing a 2 motor drivetrain, tank-style). It may not be pretty, or efficient, but it's guaranteed to work.

Not only do you have to reverse the drive speeds, but also you must remember to flip the left and right motor values, or you will find that the x-axis will be backwards.