Basic Tests To Verify Main MCB Board Operation

This page tells how to verify basic operation of the Magni robot. These tests can be used to regression test hardware and firmware changes or new production boards installed in the Magni robot. If you have Magni Silver then the robot will have a few blue LEDs on top that will be helpful but not required to do these tests.

Power Supply And Status LED Indications

There is a line of 4 power supply indicator LEDs and a ‘STAT’ or status led that are in a row to the lower left of the board. The 4 power supply leds should all be on and the status LED default state is to be on almost all the time but have very brief ‘dropout’blink that form a blink every 4 to 6 seconds. See the firmware_upgrade page for the expected blink rates of released firmware.

Revision 5.0 main control boards and after have the leds in a horizontal line with the ‘STAT’ led to the right. On version 4.9 and other early production units the LEDs are vertical with ‘STAT’ at the top of the line of leds.

If the ‘STAT’ led is off or does not blink there is something wrong with the onboard microprocessor subsystem on the main board.

Starting with version 5.2 of the main control board, MCB, there is an onboard 3.3V power supply and a blue led up near the top and a bit below the large white ‘MAIN’ 4-pin power jack. This led has the label 3.3V and must be on.

The /diagnostics ROS topic

When the robot is running quite a few pieces of diagnostic information can be viewed by looking at the ROS topic the motor node publishes. If you run the following command for a few seconds they use Control-C to stop it you can browse back and see many things helpful for diagnostic work.

rostopic echo /diagnostics       

After you have run this for a couple seconds and stopped it with control-C here are a few items that are valuable to know about for diagnostics

The Electronic Circuit Breaker, ECB’, LEDS

Starting with main board version 5.0 there are two LEDs that indicate the ECB circuit involved is active and passing power. The switch board switches must be able to control the two ECB circuits as discussed below.

On the lower left of the main board a blue LED will be ON if the Main ECB has been enabled due to the main power switch being set to the out position. The main switch is black and is to the left on the little switch board.

On the lower right of the main board a blue LED will be ON if the ESTOP switch is set to the out position AND the main power switch is also in the out position.

Serial Communications LEDS

Starting with version 5.2 of the main control board, MCB, there are two leds that show if serial communications are active between the host processor (Raspberry Pi) and the MCB. Both of these leds are located in the middle of the MCB and very high up near the white power jacks at the top of the PC board.

The lower blue LED is the SOUT led and will blink rapidly when the MCB processor is active even if there is no host processor. This LED shows the signal seen by the host processor so the level shifter must work for this to be seen.

The upper blue LED is the SIN led and will blink when the host processor is actively sending commands and queries to the MCB. This is the most important led to be blinking. It indicates of the ROS node called /motor_node is actively controlling the MCB.

Wifi HotSpot Verification

If no LAN cable is attached and if the robot has not been configured to look for a WiFi OR if no WiFi can be seen then the Magni software will create a HotSpot that you can connect to with your laptop.

If you have Magni Silver with the Sonar board then as the robot is powered up the LED2 (right LED on Sonar board as seen from the front) will light with dim blue light. After 6 or so seconds that LED will turn off. After about 16 or so seconds if WiFi is able to come up LED2 will start to blink brightly about once per second indicating that the WiFi HotSpot is up. We are working on enhancements to be available by mid 2020 which will indicate AP mode active or that the wifi specified by pifi utility is not available and perhaps more states on this led.

Starting with main control board version 5.2 there will also be a wifi led on the right visible from the front of the magni. This led is opposite from the sonar board led so it is off when the sonar board led is on and so on.

At this time if you have on your smartphone some sort of WiFi network scanner you will see a ubiquityrobotics WiFi with last 4 digits being a unique hex value.

You will also see this HotSpot show up on your laptop and will be able to connect. Read HERE for more.

I2C Bus Devices

The I2C bus on the host CPU needs to be able to communicate to a few devices on the MCB. There is an I2C excpander at addr 0x20 and RealTime clock chip at address 0x6F. If there is a OLED display loaded on P2 it is at 0x3c. We should stop the motor node then run i2cdetect which is part of i2c-tools package.

sudo systemctl stop magni-base.service
sudo i2cdetect -y 1

The above command will output 8 lines each with 16 possible hex addresses. We want to note that it detected 20 as well as 6f. If an OLED display is loaded you may also see 3c. After this test you may restart magni-base service

sudo systemctl start magni-base.service

Basic Movement Tests:

and verify that the last ‘Firmware version’ line in the log is the expected firmware version.

Distance and Low Speed Movement Tests:

Enter keyboard movement using:

rosrun teleop_twist_keyboard  

Press the ‘z’ key about 12 times until the ‘speed’ value shows about 0.15 meters per second; the ‘turn’ value will show about 0.3

At this point the robot will not move because when teleop is first entered it is in same state as if the ‘k’ was hit.

We need a second window open that we will call the ‘tf’ window; in that window type:

Also as setup have a second window open and in that type:

rosrun tf tf_echo odom base_link  

This command will continually update the robot position. There will be one line that shows the translation and 3 values that are for X,Y,Z in meters. The line will look like this if the robot was powered up in it’s current position:

Translation: [0.000, 0.000, 0.100]   at first where X and Y are 0.000.

Now we will do a few tests so make sure the robot has room to move forward about 1 meter and could have room to rotate fully. Because these tests are not precisely timed the distances and rotations will be only near the expected vaues.

RaspiCam Camera Test:

There is a very simple way to test the RaspiCam camera on the robot. This test will generate a jpeg still picture in about 6 seconds just to check the camera functionality.

raspistill -o testpicture.jpg

To verify the camera is operating properly the testpicture.jpg file needs to be moved to your laptop or other computer that has a jpeg picture viewer. If it is too difficult to move the picture using ftp or some other linux operation, the next best thing is to look at the file size. This can be done in the line below and the reply shows the 1543213 as the size in bytes for the jpeg image file.

ls -l testpicture.jpg

-rw-rw-r-- 1 ubuntu ubuntu 1543213 Aug 4 08:18 testpicture.jpg

Sonar Board Test:

If you have installed and enabled the sonar board using the install guide viewed HERE then you can verify sonar operation in realtime once the robot has been started.

The sonar node publishes a sensor_msgs/Range message for each sonar reading. Using rostopic echo /sonars you can view all the sensor readings in one topic where the frame_id of sonar_3 would be for the front facing sonar 3. Using the table that will follow you can place boxes in front of sensors to gain confidence that each sensor is showing the distance to that object. A thin bar may not be seen properly and you may get mixed messages for what is behind it or may see the bar so use large objects for this test.

There is one separate topic for each sensor as seen in the table that follows.

Topic Direction
/pi_sonar/sonar_0 Far right
/pi_sonar/sonar_1 45 degrees to the left
/pi_sonar/sonar_2 45 degrees to the right
/pi_sonar/sonar_3 Front
/pi_sonar/sonar_4 Far left

Rviz can visualize these messages as cones. There are launch files to do this in: (the source package, not the binary packages)

The move_basic node uses the messages published by the sonar node to determine proximity to obstacles.

ESTOP Testing:

(Assumes rev 5.0 or later board. If not exception will be noted)

Max Speed Limit Test:

Here we look to verify the max speed limit value will cause the robot to not exceed the default 1 meter per second setting. We will again use teleop_twist_keyboard so just keep it active OR start it like this if not running yet

rosrun teleop_twist_keyboard

Place the robot on ‘blocks’ for the front wheel so the drive wheels do not touch the floor. Normally we put a block of wood or a small stack of books under the front of the robot and it raises it up so the wheels do not touch the floor. Put a piece of tape on the outside of a wheel so while testing we can count revolutions to get the actual speed.


In the teleop window press the k key once to be in “stop” mode then press the z key several times until the “speed” value shows a value just under 1.0 meters per second. If you go too far the , (comma) key backs the speed value down.

In the teleop window press the i key repeatedly at a fast rate (3 or 4 times a second) and the wheels spin.

Verify the speed is going at 1 meter per second by watching the wheels turn 10 times in about 14 seconds. The wheels have a circumference of just near 0.64 meters. This is not a scientific test, it is looking for things being far off of the expected speed.

Deadman Timer Testing:

The robot is designed to return to zero speed if it loses touch with constant host velocity commands.

RESULT: The robot will return to stopped state with wheels actively locked.

sudo systemctl start magni-base.service

RESULT: Robot should be operational after the motor node starts (takes 15 or more seconds to start).

For re-connect of serial it will start back up in a second or less.