Robot lego nxt brick reset
This is your choice, but many commands sent to the brick only return a status byte 0 for success, or an error message. In the case of a status byte, the reply telegram is not useful. To ask for a reply, the first byte must be 0; means that the NXT must not send a reply. The second byte of a telegram is always the command number. The subsequent bytes depend on the command sent.
Its command number is 3. Then two parameters must be provided: Hence, a tone frequency of Hz for a duration of two seconds corresponds to the following bytes. We concatenate the two parts to get a complete message, and get a list of the characters corresponding to the numbers given those characters may not be viewable on your computer system with this line of code. You should hear a tone now. Because we asked for a reply the first byte was zero , we need to read it.
Again, the reply is composed of text the characters of which may not be easily viewable. Let us convert them to a list of numbers. The bytes returned are, in order: The command PlayTone does not return other information; some direct commands may return more complex telegrams.
As an example, we send the command GetBatteryLevel. This command has number 11 and requires no parameters no extra information. If a reply is asked for but it is pointless to send this command and not ask for a reply , it returns the status of the command 0 for success followed by two bytes indicating the voltage of the batteries on the NXT in millivolts.
Let us assemble the telegram, concatenate the telegram length, convert this to a list of characters, and send them. The first two bytes are the reply length 5 bytes ; 2 and 11 indicate that this is a reply for a GetBatteryLevel command; 0 indicates that the command was successful; and finally, and 27 indicate the battery voltage, which we convert to a number with fromUWORD , defined above.
Because it is more convenient to think in terms of numbers sent to the brick rather than characters, we expand the command SerialWrite contained in the package SerialIO to include the possibility of sending individual integers between 0 and bytes , and also to send a list of bytes. With this expansion, a whole message composed of bytes can be sent in one call to SerialWrite. For example, the following instructions assemble again the PlayTone command this time without a reply.
The above shows how any command can be sent to the NXT brick and its reply read. Afterward, it is simply a question of assembling a telegram in the right order with the right information, and—if asked for—reading the reply and segmenting it into the correct information.
To that end, the documentation provided by the LEGO Group [ 2 ], particularly the appendix 2 is quite complete. To make things simpler, we coded all the direct commands in a package called Math4NXT. First get the package Math4NXT. Since it uses the package SerialIO in the background, also install this package in a path that is searched by Mathematica e.
Then load Math4NXT using the following instruction. Since we did not place the package Math4NXT in a folder searched by Mathematica , we provided its path in the Needs instruction. Then open the serial port if this was not already done as before.
All the direct commands begin with the letters NXT. By default, the command returns the answer using named strings e. You can extract one piece of information as usual. This format can be changed, for example to raw i.
Alternatively, the bytes sent and received can be displayed in a separate window using the option. The Messages window opens automatically when the option is used.
The direct commands have many limitations. For one, due to the nature of the COM port, messages cannot be longer than bytes. This is a big limitation when dealing with files that can be much longer. Also, the LEGO sensors all work in very different ways; some sensors are passive, not requiring power, while others are active, and still others are programmable, like the I2C sensors.
To make use of the commands more uniformly and to avoid the length limitation, we programmed higher-level commands that deal internally with these difficulties. One example is the command M4NFileNames that lists all the files present on the brick optionally with the file size. Likewise, to facilitate the use of sensors, a command is provided that informs Mathematica of the sensor types connected. Afterward, reading the sensor is done according to the type of sensor connected.
To set the sensor type, use M4NSetSensor. After this, reading the sensor is done with a universal command, M4NReadSensor. To keep in line with the convention of direct commands, the first sensor is on the NXT input port 0.
Hence, if you connect the ultrasound sensor on the third sensor input, you can issue the following two commands. The ultrasound sensor is a complex sensor aimed at detecting the distance of obstacles in front of it in centimeters. It is equipped with a microprocessor that follows the I2C protocol. It must first be powered up and time given to it to boot up before a reading can be made.
Using the option , you see that much more exchange of information is needed to initialize an ultrasound sensor than to initialize a touch sensor. Yet, all these transactions are completely invisible with the M4N commands. The new LEGO motors contain tacho counters that keep track of the number of degrees of rotation executed. However, the direct command can only stop a motor once a target number of degrees is reached, so that in effect, the motor overturns. PID control of a motor is a more effective way of controlling rotation.
It sets a target number of degrees and adjusts the power of the motor so that it slows down when the target is almost reached using integral and derivative; see [ 4 , 5 ]. This controller is located on the NXT brick; the computer sends a target movement, and the controller takes control of the motor, adjusting the power until the target number of degrees is reached. The controller program is called MotorControl Get the program MotorControl To do so, import the contents of the file into Mathematica and download this to the NXT.
Once set this step may take a few minutes over Bluetooth as the controller is 37 kilobytes long , start the controller.
Here are the instructions to do so; the first part checks that the file is not already on the brick. Finally, inform your program of what type of motors you have and to which port they are connected using M4NSetMotor. Therefore, you do not have to worry about these technicalities and can rely on M4NSetMotor alone. Now that the controller is up and running, you can send orders to it using commands related to motors.
Once a motor is controlled by the PID controller, you should not send other instructions to it. The following instructions check that motor MOTORA is free before a movement, during the movement 10 complete turns , and six seconds after the movement began.
At the level of the program, a robot has a certain configuration, defined by what sensors are connected to the input and what motors are connected to the output. We showed two commands earlier that can be used to define the sensors and the motors.
We created a general command, M4NInitialize , whose purpose is to set all these items in one command. In addition, it can also be used to set the volume level and give a name to the brick if you have many bricks, a good habit is to rename them by the COM port to which they are connected. In addition, M4NInitialize checks that the firmware version on the NXT is compatible with this package and checks that the battery has enough charge it returns a warning if not. It is also possible to give the path of the folder containing the controller MotorControl For example, to get the current state of the touch sensors, you can follow these steps.
The ShowSensor function creates a panel with a title containing On or Off , based on the sensor value. This function uses some options for aesthetic purposes only. As a last example, we create a joystick that controls two motors.
We first define an extended ClickPane that responds to more events than the regular ClickPane function. The following shows a panel with a red dot the top of the joystick.
It constantly sets the motor power to be proportional to the position of the joystick. In addition, if the joystick is released, it returns to the center with an exponential function implemented by the variable mult. Finally, if you click the pane anywhere, the joystick instantly returns to the center with a beep.
To illustrate a simple example of an autonomous robot, we program the line-follower robot. The line should be dark on a light background or vice versa; the contrast along the edge is the important factor. To achieve this, you need a robot equipped in the front with a light detector see, for example, the assembly instructions given on p. In a first phase, we need to calibrate the sensor so that the readings on light and dark surfaces are known. Use the following to average readings while you move the robot over a white surface.
The mean of the above two values is the critical value. For a robot that follows the left edge of a dark line, for readings lighter than the mean, we want the robot to steer to the right and for readings darker than the mean, we want the robot to steer to the left.
Sam thing happened to me! It just turned off and didn't work! Can I just ask what did you do to fix it? I know this has nothing to do with roborealm That is not unexpected. If any failure happens when uploading firmware to any robot problems arise Unfortunately that does not help you much with your issues.
Have you tried to reinstall the firmware? Does the NXT respond at all in this mode? Then try the download again.