MBC IMU Gyro × EV3 Classroom

Read the IMU gyro with EV3 Classroom in three steps

In EV3 Classroom, the IMU gyro shows up as a LEGO Gyro Sensor. So you do not import a library or add an extension: you read it with the Gyro Sensor blocks. Work through the steps on the left and the blocks on the right grow with you. These block pictures were built in EV3 Classroom 1.5.3 and exported straight from the software, so they look exactly like it.

1

Start: program start + repeat forever

You need to read the sensor again and again. A new project already has the yellow "when program starts" block. Attach "forever" under it and put "wait 0.1 seconds" inside, so it reads every 0.1 seconds.

  1. Open EV3 Classroom and press "New Project".
  2. Drag "forever" from "Control" and attach it under "when program starts".
  3. Drag a "wait 1 seconds" block into forever and change the number to 0.1.
2

Meet the reading blocks (Gyro Sensor)

On the EV3, the IMU gyro shows up as a LEGO Gyro Sensor (not an infrared sensor), so you read it with the Gyro Sensor blocks in "Sensors"; no extension needed. The number at the front of each block is the port: choose 1 (the sensor is in port 1). The blocks mean something different from the stock gyro:

BlockWhat you getRange
"angle"gyro 3D heading (how far it turned)-32768 ~ 32767 degrees (0 at power-on / reset, bigger turning right)
"rate"fused heading (not degrees per second)-32768 ~ 32767 degrees (0 at power-on / reset, bigger turning right)
"reset angle"zero all four headings—

Use blocks of only one mode in a program. Every mode change makes the EV3 pause for about 0.5 seconds.

3

Show it on the EV3 screen

Put the reading block into "write … at line …" from "Display", use "join" from "Operators" to put a name in front (for example ANGLE), and start the program with "clear display". Click a function and the blocks and result change to its example.

Sensor simulator: the left picture is seen from above (heading), the right one from the side (pitch). Drag the sliders and press the buttons, and watch the output change

The simulator is only a picture: values come from the robot's direction and angle on screen, not the sensor's own algorithm. The "Zero" button = the gyro "reset"; the pitch slider and the shaking rates cannot be read in this software (use Pybricks / clev3r).

Block example for each function

Every value EV3 Classroom can read has a small program you can copy (sensor in port 1). Press "Try it" to jump to step 3.

What EV3 Classroom cannot read: the gyro 1D and magnetic headings (Classroom has no "angle and rate" block), the yaw rate, pitch and pitch rate (modes 2, 5 and 6, added in firmware v4.0). For these, use Pybricks or clev3r. Magnetometer trust, face up, raw 9-axis values and the calibration commands cannot be read on the EV3 at all (use Arduino, mBlock or micro:bit).

Things to know

  1. Plug the sensor into port 1. If you use another port, change the port number on the block. Switch the EV3 on first, then plug in the sensor (keep the robot still then); if the number never changes, unplug it and plug it in again.
  2. "rate" is not degrees per second: this gyro puts the fused heading (the heading that does not drift) in "rate". For degrees per second, read mode 2 with Pybricks / clev3r.
  3. Use one mode per program. Each mode change makes the EV3 pause for about 0.5 seconds, and a racing robot can lose control; "reset" needs no mode change.
  4. When the sensor is unplugged: the EV3 cannot read it, the number becomes "not a number" and the screen shows ----. Each reading also waits about 1.2 seconds. The program does not stop, and it works again when you plug the sensor back in.
  5. Direction: turning right makes the heading bigger, left smaller; one turn = 360 and it keeps adding up. If right makes it smaller, the sensor is mounted upside down.
  6. English blocks: EV3 Classroom has only English and Simplified Chinese interfaces; this page uses English.
  7. For complete projects (turning 90°, a square, driving straight …) see the EV3 examples page; the first 5 examples have an EV3 Classroom file to download.