Updated mBot extention for App Inventor: missing blocks


After updating mBot extension to my app at MIT App Inventor site, I found #when mBot1.connected# block missed. I don’t know who I should report.


Hi BotCoder,

Did you refer to this instruction to build the mBot extension on MIT APP Inventor?


Yes, I am referring to this page.


Please use this program block, it has the same function with the previous one.


I have tried those two extensions, mbot.aix and ranger.aix. None of them shows the program block you suggested to use.

Ref: http://appinventor-en.makeblock.com/


Hi BotCoder,

The success connected C-type block may not be updated on the site properly. Our engineer will update these days.
Here I attach it and you can download first.extensions2.0.2.zip (1.4 MB)



I have updated mBot blocks with the new extensions 2.0.2. After replacing the "when mBot1.connected# with #mBot1.connectedToRobot# block, the app works as expected during the connection with MIT AI Companion. However, the editor fails to compile the app. With the older extension, the app was compiled with success. Please download the attached below. You might be able to investigate why the editor won’t be able to compile.

Thank you.

MBot2_SpeedTester.zip (757.0 KB)


Hi BotCoder,

There is no compiling issue with the file you sent. It install success and run success.

Is there any detailed info about the editor fails issue while compiling? Like any error message? You may take a some pictures for it if there is.


Thank you for checking my app.

I think it is an issue MIT App Inventor has to deal with. I tried the one I sent to you and got it compiled successfully but not the original. Strange.


These extensions have not been updated here - http://appinventor-en.makeblock.com/

I had blocks missing when updating from that site. I found this file (extensions2.0.2.zip) in this post and I now have more blocks. Getting ready to try them out. Thanks for this file, but have the website updated please - http://appinventor-en.makeblock.com/.



Thanks for your reminder, we will urge our engineers to update it asap.


I am not sure how to get the Claw Arm motor to move and the Claw motor to move. I don’t see blocks in MIT App Inventor to make these motors move. I see a “.setStepperMotor” block and a “.setEncoderMotorRotateAtSpeed” block, but neither of these motors are stepper motors or an encoder motor. I am able to make the clawbot from the Ultimate 2.0 kit to move forward, backward, right and left from an MIT App Inventor app I created.

Please instruct how to get the claw arm to move and the claw to open and close.




The three motors on Ultimate 2.0 are encoder motors. Then MegaPi board support the encoder motors in APP inventor.
While if you want to control the claw, since the small motor in the claw is dc motor, it is not supported by APP inventor.


Can you give me example values or value ranges for the “.setEncoderMotorRotateAtSpeed” block? Port, Speed and Angle

Is there a technical guidance documents I can have for the blocks for MIT App inventor that will examples or tell me possible values for all the blocks? If so, I am an educator and have mCore, Orion and MegaPi boards.




Here is an example picture for you:

The Slot means the port on the MegaPi, there are four motor ports on MegaPi, so the slot range is 1~4;
The speed value is same with the speed value on mBlock program, its range is 0~255.
As for the angle, there is no limit for its range, the larger angle you set, the longer time the motor will keep rotating.


So I have tried the values you suggested and “.setEncoderMotorRotateAtSpeed” does not work. I can get motors to work with “.MoveForward”, “.MoveBackward”, “.TurnRight” and “.TurnLeft” so I have the motors connected to the MegaPi correctly and the bluetooth is working when those blocks are inserted. So I am inclined to think this block doesn’t work. I can’t use the other blocks because they make two motors rotate at the same time. I want only one motor to turn at a time. Maybe knowing what is working for me will help you know what I am doing wrong or realize your engineers need to fix this block. Please give some suggestions to try. Thanks.


Maybe we should move these comments (Jan 9 to today) to another thread, named - Getting MegaPi to control motors in MIT App inventor"



We have done the test with the block “setEncoderMotorRotateAtSpee”, it does have the problem.
It will be fixed on the next version extension.