Controlling robots with microcontrollers simplified

Rules

• Send everything with Radio → “radio send string”, on your team’s radio group.
• Movement commands must be repeated: the car stops by itself if no movement command arrives for 80 ms. Send one every 40 ms.
• NEXT_COLOR and EMERGENCY are sent once per press, not repeatedly.

In MakeCode Blocks

1. From Radio, drag “radio set group” into “on start” and set it to your team’s number (you get it at the start of the session).

In MakeCode Blocks

1. Add Input → “on shake”.
2. Inside it, put Radio → “radio send string” with the text EMERGENCY.
3. Add Basic → “pause (ms)” 200 after it, so one shake sends only one message.

In MakeCode Blocks

1. Create two variables in Variables: last_ab and ab_state. In “on start”, set last_ab to false (Logic).
2. In “forever”, set ab_state to Input → “button A+B is pressed”.
3. Add an “if”: when ab_state is true and last_ab is not true (Logic → “and”, “not”), send the string NEXT_COLOR and pause 150 ms.
4. After the “if”, set last_ab to ab_state.

In MakeCode Blocks

1. In “forever”, below the colour block, add an “if / else if / else”.
2. If button A is pressed, send SL. Else if button B is pressed, send SR. Else, send S.
3. At the very end of “forever”, add “pause (ms)” 40.

In MakeCode Blocks

1. In the “else” branch, set two new variables: pitch to Input → more → “rotation (°) pitch”, and roll to “rotation (°) roll”.
2. If the absolute value of pitch is less than 20 and the absolute value of roll is less than 20 (Math → “absolute of”), send S. The board is held flat.
3. Else, if the absolute value of roll is at least the absolute value of pitch, the tilt is sideways: send L if roll is less than 0, otherwise send R.
4. Otherwise the tilt is forward or back: send F if pitch is less than 0, otherwise send B.

In MakeCode Blocks

1. Create a variable cmd. Wherever you send F, B, L, R, SL, SR or S, also set cmd to the same text.
2. Add a second “forever” block. In it: if cmd = F, show arrow North; if B, South; if L or SL, West; if R or SR, East; otherwise, clear screen.
3. Why a second “forever”? Showing an arrow takes a moment. In its own loop it does not slow down the radio messages. If they paused for more than 80 ms, the car would stop.
4. In “on shake”, after sending EMERGENCY, add Basic → “show icon” with the X icon and a short melody from Music. Choose the “in background” option, so the program does not wait for the music.
5. In the A+B colour branch, add a short tone from Music, also played in the background.

In MakeCode Blocks

1. Open DeepDive Robot.hex in MakeCode (Import → Import File). This is the car’s program.
2. Diagonal: a Mecanum car drives diagonally when only two opposite wheels turn. Create car_forward_left: upper right and lower left motors forward, the other two at speed 0. Create car_forward_right: upper left and lower right motors forward, the other two at speed 0.
3. In the car’s movement chain (where it checks F, B, L…), add: if the command is FL, call car_forward_left; if FR, call car_forward_right.
4. Speed: create a variable speed in the car’s program, set it to 50 at start, and use it instead of the fixed 50 in every motor block.
5. Where the car handles NEXT_COLOR and EMERGENCY, add SPD: each SPD moves speed to the next step (30 → 50 → 80 → 30). It must sit there, before the movement handling, because SPD is sent once and is not a movement.
6. Flash the new program onto the car’s micro:bit.
7. In the controller: when tilted forward and sideways at the same time (pitch below -20 and roll below -20, or pitch below -20 and roll above 20), send FL or FR. Put this check first, before the other tilt checks. Add Input → “on logo pressed” that sends SPD once.