Handheld XV-11 LIDAR with STM32F429 and MATLAB
The XV-11 LIDAR unit
Throughout the years though Vacuum Clearner robots have evolved a lot, both in the algorithms gettings better but also in the use of more advanced sensors. Lately the Neato XV-11 All Floor Robotic Vacuum System included a small range (0.2m to 6m) LIDAR with 1 degree precision and a resolution of a couple of centimeters. As this vacuum cleaner only costs around $400 makes it a bargain to get hold of a LIDAR if just you could disassemble the robot and use just the LIDAR.
Luckily for us there was put up a bounty for people “hacking” the XV-11 LIDAR and a new hacking community had begun: xv11hacking – LIDAR Sensor http://xv11hacking.wikispaces.com/LIDAR+Sensor
When spinning the XV-11 LIDAR unit itself spits out quite a lot of data on a UART port at 115200 baud. A full rotation, meaning 360 distance measurements, consists of 1980 bytes and is sent out with a refresh rate of 5 Hz. So it’s quite an amount of data is required to be processed in a relatively short amount of time.
The mechanical design of the XV-11 LIDAR
Compared to the more expensive LIDAR sensors on the market you will for sure not get same resolution and accuracy with the XV-11 LIDAR, though for hobby and lower cost research this LIDAR will do you just fine.
We purchased one of the XV-11 LIDAR units on eBay, sold as a “replacement unit” for the Neato vacuum cleaner. This was only $100 so quite a good deal for us.
We decided to connect the LIDAR to our STM32F429IDISCOVERY board for processing and display, due to the heavy amount of transmitted data and the use of the built-in Touch Display for display of the distance measurements.
Below you will find a video of the project in action.
The source code for the STM32, including the CoIDE project and of course the MATLAB script for display, can be found at our GitHub at: https://www.github.com/TKJElectronics/XV11Lidar_STM32F429
As many have been requesting a very exact description of the connection layout I will here try to explain it in three simple lines, as the connection is very simply.
The XV-11 LIDAR unit contains two cables, one with 2 wires defined as the MOTOR CABLE and one with 4 defined as the DATA CABLE.
- The RED wire in the MOTOR CABLE should be connected to 3.3V for free running (open loop). Otherwise this should be pulsed with 12V.
- The BLACK wire in the MOTOR CABLE should be connected to ground.
- The RED wire in the DATA CABLE should be connected to 5V or 3.3V. Usually it is 5V in most of the units you can find on the market.
- The BLACK wire in the DATA CABLE should be connected to ground.
- The BROWN wire in the DATA CABLE should be connected to GPIOC.10 on the STM32F4 board, as this is the LIDAR RX being connected to the STM32F4 UART TX.
- The ORANGE wire in the DATA CABLE should be connected to GPIOC.11 on the STM32F4 board, as this is the LIDAR TX being connected to the STM32F4 UART RX.
I hope this clears up all the connection questions.
The next steps of this project is to implement and use the XV-11 sensor on either the Balanduino or an Omniwheel robot
Finally the very future plans is to use the LIDAR coupled together with an Optical Flow Sensor on our Quadcopters to make them completely autonomous:
IMU+GPS+Optical Flow+LIDAR = Autonomous navigation in unknown environments
I have a remote controlled lawnmower that I would like to convert to a robotic mower. You can view my mower at:
http://www.instructables.com/member/Bob+Bowie/
I am familiar with BASIC programming and have purchased a Basic Stamp
http://www.mouser.com/ProductDetail/Parallax/555-28188/?qs=vI1DwPFGRq81pc2dsW7JNA%3D%3D&gclid=CjwKEAjw-o6hBRDOmsPSjqakuzYSJADR2V3SAEyuNCxhe0bvRcMNrn1gCwetoimyhB8opYJPzYYQJhoCFRfw_wcB
I am hoping that you might be able to guide me. The steps I envision are:
Step #1-Learn Mode
Capture/Record the Servo commands from the Futaba receiver to the Basic Stamp while sending these same commands to the 2 Astro-flight 208d Reversing Controllers which drive the 2 wheel chair motors.
Step #2-Playback Mode
Place the mower in the same start position and send commands recorded in Step #1 to the 2 Astro-flight 208d Reversing Controllers which drive the 2 wheel chair motors.
I have been able to program the Basic Stamp to send commands to the 208d’s, but wheel slip presents a need to periodically determine location (x,y). Determining location will allow for commands to be sent to the 208d’s to correct location-this is where I need help! Is Lidar the solution?
Specs on the Astro-flight controllers (208d’s) can be viewed at:
http://www.astroflight.com/208d.html
Thank you,
Bob Bowie
Bob, I’m just another visitor, so I don’t speak for TKJ. But I have this lidar sensor and have built outdoor robots. This particular lidar just doesn’t have the intensity to work well in full sunlight. Like the Kinect, it was built for indoor applications. It is also planar – it doesn’t do 3D. For outdoor odometry, you should probably look into the kind of optical flow sensors people are using on multicopters – though it won’t help with obstacle avoidance. Outdoor capable lidar remains too pricey for your application.
@Bob Bowie
@Pondersome
Hi Bob and Pondersome.
I am currently in touch with Bob about discussing which options would be available for his lawnmower. But I completely agree with you Pondersome that this specific inexpensive LIDAR unit won’t work the best in outdoor environments, so I have also already been recommending other solutions such as RTK GPS (expensive though), positional radio-tracking, wires in the edges of the lawn for wireless mapping.
For the optical flow sensor that you are mentioning this unfortunately won’t be to much help as we would like to exactly determine the current position of the mower. But it could be used as a combination with the GPS for more exact result.
Regards Thomas
The optical flow suggestion was just for dead reckoning as an improvement over wheel encoders – it certainly wouldn’t lead to absolute positioning without a known starting position and strong correction.
Thomas, do you have any electrical setup instructions for the XV11 code you posted? I’ve been able to compile and load the software onto the discovery board, but not get any display of lidar readings. Maybe that’s partly because of the bluetooth module you added and which I don’t have. It seems like you are using USART 3 to drive receive of data from the lidar and send forward to the bluetooth module? I noticed in the video that you don’t have the brown receive wire from the lidar connected, but I can’t make out all the connections visually. So I’m assuming your program does not need to send data to the lidar unit. Do you think it should still work without the bluetooth module connected? If not could you give me a hint how to modify it to bypass that? I’m new to the STM32 platform.
I also noticed that the PC10 line which I think is what you defined for the bluetooth serial connection is internally connected to the R2 line of the LCD-RGB interface and was wondering if writing to that is somehow intentional? Any advice you can provide is helpful. Thanks.
Actually, no worries. Persevered and whether it was disabling the serial writes or fixing up the voltage to the lidar sensor, the example now works! Thanks for sharing it.
@Pondersome
So you got it working? What was the problem then.
The UART transmission is not necessary for just displaying the data on the touch display.
Regards Thomas
Great little project!
How are you putting together the code for the Discovery board?
I’ll download the files and see what’t in there …
Cheers!
Chris Arena
Portsmouth, Rhode Island, USA
@Chris Arena
What do you mean with putting together the code.
The project is made within CoIDE where the code can be programmed and debugged with the onboard programmer on the Discovery board.
Regards Thomas
Your program is great, thank you. I have the STM32F429 Board. The UART RX gives me a HardFault while in SyncUp(). Any debug suggestions? What Stack and Heap size do you use?
Make sure that the UART RX data is received correctly and that interrupts are being generated everytime a byte is sent.
Please have in mind that this project is made as a quick prototype why the UART receive buffer might be overflowed if the data is not processed quickly enough.
What power supply are you using for the XV-11? I am trying to power it from another STM32 Discovery Board. But XV-11 keeps rebooting and not transmitting proper serial.
To read the ASCII code correctly I have to shift it by 255 and divide by 2. Do I have a serial hardware or setup problem? Maybe insufficient current supply.
@Blair Kingsland
We are just using a 1-cell LiPo battery which powers the STM32F4 DISCOVERY board and the motor in the XV-11 sensor.
Please be sure that your power source is capable of providing the necessary current without making the motor rotate too fast. If you power the motor directly from a regulated power supply, the voltage should be between 3-4V as the motor will otherwise spin too fast.
USB 5V should supply sufficient current. Motor is powered at 2.96V. Maybe too slow.
Hi! I am wondering if anyone can help me out with the code and wiring for this to hook up to an ardunio uno! Im working on a project of my own with a little robotic vehicle, and would like to implement this! Thanks! You could email me at hcf5034 – at- psu -dot- edu
@Charles
Getting the XV-11 to work with an Arduino Uno might be difficult due to the large amount of data which is transmitted at a 5 Hz rate.
Therefore quite a lot of RAM is needed to store a full 360-degree scan (1980 bytes at least) whereafter you want to process all the data to extract the actual distance measurements. This is a time consuming task, though it is doable but due to the amount of RAM needed I would recommend to do it on at least an Arduino Mega.
nice project. I am currently working on the similar project
but the Lidar should sending out the distance data to the board
but how do you know which data is going into which position?
thank you
@gyuhyong
You are correct that LiDAR data only corresponds to measured distances relative to the robot.
To map the environment you will have to investigate what is known as Simultaneous Location and Mapping (SLAM)
I can recommend you to take a look at this series of video lectures which in great detail go through the theoretical understanding and practical implementation of a LiDAR-based SLAM algorithm.
https://www.youtube.com/playlist?list=PLpUPoM7Rgzi_7YWn14Va2FODh7LzADBSm
Good luck with your project.
I noticed that you have chosen PC10 and PC11 to communicate with Lidar, but also use them to connect bluetooth in your code, aren’t you??
@Jenny
That’s correct. Even though I write that the BROWN cable to the LiDAR, being the LiDAR RX pin, can be connected to the TX pin on the STM32 I did not actually do this.
Instead I decided to share the UART periphiral for both reception of LiDAR data and transmission of parsed data to the Bluetooth module for wireless transmission to the PC.
Hi,
I am currently using a RPLIDAR A1M8 sensor for my project. Unfortunately I see no output on my STM32F429i Discobvery board. Do anyone know which settings I have to make in the code?
Thanks
@Mike28
This project and the code is currently only supporting the XV11 LiDAR.
To add support for the RPLIDAR you will have to change the driver code which decodes the incoming packages. This is currently done in these lines: https://github.com/TKJElectronics/XV11Lidar_STM32F429/blob/master/main.c#L222-L337
While parsing the packages the ‘Distance[360]’ array is continuously updated with the latest distance measurements corresponding to the indexed angle.
As inspiration I suggest you take a look at the following Arduino library for the RPLiDAR: https://github.com/robopeak/rplidar_arduino/tree/master/RPLidarDriver
I need your project file,for example Keil uVision5.
Can you give me,Thank you. ^^
@BoYan
I dont have Keil project files as this project wasn’t made CooCox CoIDE.
For projects like this I would suggest that you use Open Source tools since the majority of the online community prefers this.
Hi, We will make this project with Ydlidar X4. Details and Datasheet are in this website http://ydlidar.com/download . Your codes are worked by us with True Studio. But we don’t leave this part (loop) in serial.c :
int16_t Serial_Buffer_Get(void)
{
if (bufferReadPos != bufferWritePos)
{
return receiveBuffer[bufferReadPos++];
} else {
return -1;
}
}
And we don’t leave this part (loop) in main.c :
void SyncUp(void)
{
uint8_t i;
int16_t ch = 0;
int16_t ch2 = 0;
Serial_Buffer_Clear();
while (ch != XV11_START_BYTE) {
while (Serial_Buffer_Get() != XV11_START_BYTE);
i = XV11_PACKAGE_LENGTH;
while (i > 0) {
ch = Serial_Buffer_Get();
if (ch >= 0) i–;
}
// read the rest
i = XV11_PACKAGE_LENGTH – 1;
while (i > 0) {
ch2 = Serial_Buffer_Get();
if (ch2 >= 0) i–;
}
}
}
We would appreciate if you could help us.
@Jacket
I’m not sure I understand your question or problem? Please clarify what is not working?
we cannot get lidar’s map data from lidar to stm .we cant see map on stm .because we are using another lidar (YDlidar X4 model) how can be embedded the start byte in source code please help us
@suat yıldız
If your LiDAR is using a different communication protocol, you will have to modify the communication driver in our firmware to match your specific LiDAR.
Basically you need to program the driver to read all the incoming distance measurements into the array: Distance[]
This requires that you modify the functions: SyncUp(), LoadPackage() and ParsePackage()
Can we us tf mini
Hi, we bought same equipments for this project. We have XV-11 Lidar and STM32F429 Discovery Board (DISCO). We tried to work code without Bluetooth module.
On STM, only “Pause and Scan” were output and we were unable to retrieve the data from the lidar and we didn’t see mapping. Is it possible to receive data on STM without Bluetooth? We took this project as a graduation project and we really need your help to a great extent. If necessary, we can take the screen shot.
@Volkan Ayhan
Yes, the project should indeed work without the Bluetooth module. The Bluetooth module is only for debugging purposes.
If you do not see the scan the serial data is likely not coming in from the LiDAR. Please try and connect a logic analyzer or oscilloscope to the ORANGE wire of the DATA CABLE (LiDAR TX).
1. If no data is transmitted it might indicate that the LiDAR is not powered correctly. Please ensure that 5V is supplied to the RED wire in the DATA CABLE.
2. If some data is transmitted but no scans show up, the LiDAR might not be spinning fast enough or is spinning too fast. In open-loop mode please ensure that 3.3V or close to 3.3V is supplied to the motor. But it is even better to create a closed-loop speed controller for the motor. Connect the motor through a transistor or MOSFET and adjust the speed using PWM according to the speed feedback value (RPM) sent by the LiDAR.
@Mike28
Hello Mike,
I’m working on the same thing and were you able to achieve the output? Could you please share your code so that I can figure out what’s happening
Hello Mr.
I am struggling with Xiaomi Lidar 2nd edition, STM32F407 (MATLAB, Keil). I can read data but how can I analyze it I have no information about it. Can you help me about this 8 bit data means? How can I plot or at least analyze this 8 bit values? What is the distance, what is the angle?
@Murat
Hi.
I am not sure that the Xiaomi LiDAR uses the same protocol. If it does, I woul recommend you to read the XV11 hacking guide which includes the data protocol: http://blog.tkjelectronics.dk/wp-content/uploads/2014/08/xv11hacking-LIDAR-Sensor.pdf
Regards Thomas
Hello Sir,
I am trying understand these functions – SyncUp(), LoadPackage(), ParsePackage(). What it need to change in this functions to make it works with RPLiDAR? At the moment, I changed start bit and package length values, but what to do with other variables?
Hi,
I am working with the same project using IAR workbench and cubeMX, i have no idea how to plot the data, on LCD board. i am receiving the output which is random. Can you e-mail to my mail ID please.