Write a drive program

On this page you will start from an empty project and write a program for two motors that you drive with a gamepad. By the end, you will have built the Tank Drive example's program yourself. In the example, the right motor's reversed checkbox is also checked.

Probot Blocks screen; the Tank Drive example is loaded and its code shows in Code Preview.

Before you start

Blocks is open and the Probot Blocks tab is selected.
The workspace holds only the six lifecycle blocks. If not, see Start over.
Know the motor driver pins on your robot. This page uses the pins from the examples: left motor 16 and 17, right motor 18 and 19.

To see the finished result, open Pick an example > Tank Drive.

Get to know the lifecycle blocks

The program is split into six blocks. Each block runs at a certain moment in the robot's life. TeleOp (driver control) is the part where you drive the robot with the gamepad.

Block	When it runs	What goes in it
robotInit	Once, when you press Init on the Driver Station	Motor and pin definitions
robotEnd	Once, when you press Stop	Stopping the motors
autonomousInit	Once, when autonomous starts	Getting ready for autonomous
autonomousLoop	About 50 times per second during autonomous	Autonomous moves
teleopInit	Once, when TeleOp starts	Getting ready for TeleOp
teleopLoop	About 50 times per second during TeleOp	Reading the gamepad and driving

Do not wait longer than 2 seconds inside a loop block. The robot counts that as a deadline miss.

Create the right motor's name

Motor names are stored as variables. In the define motor, drive motor and stop motor blocks, the default name is solMotor.

sagMotor comes ready only in the tank drive and arcade drive blocks. You will define the motors before the drive block, so create this name yourself first.

Do not use Turkish letters or spaces in a variable name. Blocks changes these characters in the code: a space becomes _, and a Turkish letter turns into characters like _C4_9F. For example, sağMotor becomes sa_C4_9FMotor, which still compiles but is hard to read.

In the block list, select the Variables category.
In the block panel, press Create variable....
1. In the "New variable name:" box, type sagMotor.
Press OK.

Result: The block panel shows blocks named sagMotor.

Define the motors

Tip

Drop each block inside a lifecycle block so that its notch clicks into place. A block left outside does not go into the code.

In the block list, select the Motor & Drive category.
Drag the define motor block into robotInit. It comes with the name solMotor and pins 16 and 17.
Drag a second define motor block under the first one.
On the second block, press the solMotor ▾ dropdown and select sagMotor.
On the second block, type 18 in RPWM pin and 19 in LPWM pin.
If the right motor turns the wrong way, check the reversed checkbox on the second block.

Result: In Code Preview, the line const uint8_t sagMotor_RPWM = 18; appears.

Stop the motors

From Motor & Drive, drag the stop motor block into robotEnd.
Drag a second stop motor block under it.
On the second block, select sagMotor from the dropdown.

Result: In Code Preview, two setMotor( lines appear inside void robotEnd(). When you press Stop on the Driver Station, both motors stop.

Drive with the gamepad

From Gamepad, drag the read gamepad block into teleopLoop.
From Motor & Drive, drag the tank drive block under read gamepad.
From Gamepad, plug the js left stick ↕ (forward +) block into the left power slot of tank drive.
Plug another js left stick ↕ (forward +) block into the right power slot.
On the block in right power, press the left stick ↕ (forward +) ▾ dropdown and select right stick ↕ (forward +).
1. The 0 blocks that were in the slots drop into the workspace. Drag them to the trash can.

Result: The left stick block is in the left power slot and the right stick block is in the right power slot. On the robot, the left stick drives the left motor and the right stick drives the right motor. When you push a stick all the way forward, the value is +1.

Check the code

In the workspace, drag any block left outside the lifecycle blocks to the trash can.
In the side panel, move the mouse over Code Preview.
With the mouse wheel, scroll Code Preview down to the void teleopLoop() line.

Result: Inside void teleopLoop(), an auto js = ... line and two setMotor( lines appear. The code is ready to upload to the board.

To save it, press Download blocks. To upload it to the board, press Download .ino.

Having trouble?

The block does not show up in the code: The block is not sitting inside a lifecycle block. Drag the block back into a lifecycle block. See Troubleshooting.
The two motors do not turn the same way: Check the reversed checkbox in the define motor block of the motor that turns the wrong way.
The robot keeps drifting a little: Raise the deadzone value in the read gamepad block (at most 0.5).

Next step

Upload the code to the Probot board