Since the launch of LEGO MINDSTORMS in 1998, three generations of MINDSTORMS products have been on the market:
- 1998: LEGO MINDSTORMS (RCX)
- 2006: LEGO MINDSTORMS NXT
- 2013: LEGO MINDSTORMS EV3
Several LEGO sets have been released for each generation, but the Programmable Brick (Figure 1) is what makes each generation unique. Here’s an incomplete list of LEGO MINDSTORMS sets released since 1998.
- LEGO MINDSTORMS (RCX)
- 1998 – LEGO MINDSTORMS Robotics Invention System
- 1998 – LEGO MINDSTORMS Education Set
- 1999 – LEGO MINDSTORMS Robotics Invention System 1.5
- 2001 – LEGO MINDSTORMS Robotics Invention System 2.0
- LEGO MINDSTORMS NXT (See full article on NXT versions)
- 2006 – LEGO MINDSTORMS NXT Education Set (9797)
- 2006 – LEGO MINDSTORMS NXT (8527)
- 2009 – LEGO MINDSTORMS NXT 2.0 (8547)
- LEGO MINDSTORMS EV3 (See full article on EV3 versions)
- 2013 – LEGO MINDSTORMS EV3 (31313)
- 2013 – LEGO MINDSTORMS Education EV3 Core Set (45544)
All versions of LEGO MINDSTORMS NXT sets contain NXT bricks with the same functionality. NXT bricks found “NXT 2.0” sets have exactly the same specs as NXT bricks from other sets. Likewise, all versions of LEGO MINDSTORMS EV3 contain the same EV3 brick. So despite the large number of LEGO MINDSTORMS sets that have been made, only three versions of LEGO MINDSTORMS exist: RCX, NXT, and EV3. This article does not aim to introduce MINDSTORMS NXT and EV3 from the start, but it discusses some of the differences between NXT and EV3, as well as compatibility between the two systems.
EV3 brick and NXT brick compared
LEGO MINDSTORMS EV3 is the latest generation of LEGO MINDSTORMS, released in 2013. LEGO has stopped selling the NXT system in retail stores, but NXT products and support may continue to be available through educational channels for a while.
In general, LEGO MINDSTORMS EV3 is more powerful than LEGO MINDSTORMS NXT. If you do not have any LEGO MINDSTORMS sets yet, I recommend to go for EV3, so you’ll have the latest, most powerful LEGO robotics system to date.
EV3 Brick features
The main difference between the NXT system (the Programmable brick, motors and sensors) and the EV3 system is the brick itself. The EV3 brick features a more powerful processor, 4 motor ports (instead of 3), a micro SD card slot, a USB host port and a Linux operating system. In addition, it has a slightly larger screen, more buttons, and it is possible to control the EV3 brick using both iOS and Android devices, as opposed to Android only for the NXT. See this article for a list of technical specifications of both bricks.
Why a micro SD card slot, a USB host port and Linux?
On first thought, you may wonder why you would need these features. First, the micro SD card slot can be used to add extra storage to the brick by means of a micro SD card. Additionally, the USB port can be used to link up to four EV3 bricks so that you can control up to 16 motors and 16 sensors on one robot.
Although the general user will not notice on the outside, the brick runs a Linux based operating system. Basically, this means that your robot almost resembles a full computer, a bit like the Raspberry Pi! This means that you can add other devices to the USB port on the brick, such as a WiFi dongle for wireless connectivity (Figure 2), a USB keyboard for extra input, or a USB webcam for object detection.
Note that while the possibilities are endless in theory, we’ll have to wait for people in the LEGO MINDSTORMS community to develop specialised software for such devices, so that the rest of us can use them on our robots. For example, before you can use your USB keyboard as a ‘sensor’ inside the LEGO MINDSTORMS EV3 software, someone will have to create a custom sensor block that tells your robot which buttons on the keyboard are being pressed.
EV3 Motors and EV3 Sensors
Both versions of the EV3 set come with a variety of sensors (see details; coming soon). If you have an NXT set, you’ll recognize some of the new sensors. The EV3 Touch sensor, EV3 Color Sensor, EV3 Ultrasonic Sensor (Education set only), closely resemble their NXT counterparts. New sensors for the EV3 system include a gyroscope (Education set only) and an Infrared Proximity Sensor with Remote Control (Home edition only). Figure 3 shows the complete family of EV3 electronic components.
Both versions of the EV3 set contain two Large motors. They are comparable to NXT motors in terms of speed and torque, although their shape is slightly different to make building easier. In addition, both sets have one Medium motor, comparable to the Power Functions Medium motor. As is the case for NXT, all three motors have rotation sensors for position and speed control.
The cable connectors in the NXT sets and EV3 sets are the same, so that many of the EV3 and NXT devices can be used together. Some combinations are compatible, others are not, as discussed in the next. You can see a demonstration of two possible configurations in the following video.
Most NXT accessories can be used with the EV3 brick
You can connect all official LEGO NXT motors and official LEGO NXT sensors to the EV3 brick. For example, you can have a configuration with an NXT Touch Sensor, an EV3 Touch Sensor, an NXT motor and a Medium EV3 motor, all connected to the EV3 brick, as shown in Figure 4. You use the NXT devices in the EV3 software as if they are EV3 components, as demonstrated in the video.
You can also connect some unofficial NXT Sensors to the EV3 brick, such as some sensors from HiTechnic, Mindsensors and Dexter Industries. However, these companies will have to create programming blocks to facilitate the use of these sensors in the LEGO MINDSTORMS EV3 software, which has not yet been done for all sensors. If in doubt, contact the manufacturer of the sensor. If you have a very old version of the NXT Touch sensor, it may not be compatible with the EV3 without some modifications (see the comments by Philo below).
EV3 sensors CANNOT be used with the NXT brick, but EV3 motors CAN be used with the NXT
It is not possible to connect the new EV3 sensors to the NXT brick. However, you can use both Large and Medium EV3 motors with the NXT brick as if they are normal NXT motors. Figure 5 illustrates this (see video above for a sample program).
The NXT and EV3 rechargeable batteries are not compatible
Both the NXT and EV3 can be powered with 6 standard AA batteries. Alternatively, they can be powered with a LEGO rechargeable battery. The LEGO EV3 battery and LEGO NXT battery have a different shape, as shown in Figure 6, so you cannot use them interchangeably.
The EV3 brick is programmed with new programming software. Although the software is different than the NXT programming software, existing NXT users will recognize many of the features of the EV3 software. You can still program the robot’s actions using drag and drop programming blocks, as shown in Figure 7.
It is also possible to use the EV3 software to program your NXT bricks. If you have both NXT and EV3 bricks, this allows you to program both using just one application. Note that this does not give your NXT brick additional features. For example, you still cannot use EV3 sensors on the NXT brick. It just helps keeping all your programs in one place. The EV3 software (home edition) will be a free download from the LEGO MINDSTORMS website [click here], so you can use it even if you do not have an EV3 set.
Questions & Updates
Feel free to post questions in the comments below. I’ll try to answer your questions and add them to the article if necessary. If you find any errors, please let me know.
All text and illustrations in this article (c) Laurens Valk 2013