Before starting on this section you will need to have a working ubuntu partition and all software installed on the initial readme, as well as all the required tools mentioned there as well.
If you do not know how to solder watch the video below on how to solder electrical components.
The goal of this section is to flash the needed firmware onto the Adafruit ItsyBitsy.
In order to run the robot we will be using the source code provided by the lab.
However you do not need to download or compile this code we have already done that for you.
To get the pre-complied code, visit here and download the lastest version of
CURRENT.UF2
In order to program the ItsyBitsy we will be using Adafruits Flashdrive Emulation.
Installing The Firmware
- Plug in the ItsyBitsy to your computer using the micro-usb cable in your kit.
-
Open up 2 File Explorer Windows on Ubuntu.
-
Navigate to the download location of the firmware in one window (Probably your
DownloadsFolder).
-
Double Click the reset button on the ItsyBitsy. This will put it in bootloader mode. The ItsyBitsy should disappear momentarily and then show up as
ITSYM4BOOT.
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Open ITSYM4BOOT in the other window and drag
Current.UF2into it.
-
A replace file nofication will show up click the green replace button.
The ItsyBitsy should then disconnect and not reappear
Congrats! You've flashed the firmware on the ItsyBitsy!
Go ahead and disconnect it from your computer.
If you see
curcuitpython
as the flash drive name instead of
ItsyM4Boot
then DOUBLE CLICK the reset button on the ItsyBitsy.
- Solder header pins onto the ItsyBitsy with headers and place it in the breadboard. Note you only need to solder pins to the long sides of the board don't worry about the back. See pic below for more reference.
Protip: a pair of pliers makes snapping the correct number of header pins much easier.
- Find the 74hc126 line driver and place it in the breadboard.
- Use the double stick tape to attach the barrel jack adapter to the side of the breadboard.
Protip: Apply pressure to the taped objects for at least 30 seconds to ensure a good bond. Cut your tape to exact sizes to ensure neatness.
Then wire the barrel jack termianls to their respective rails on the breadboard.
- Wiring up the Smart Servo Cables
In order to connect the smart servo cables to the breadboard we need to use the double header pins. Take three double header pins and insert them into the smart servo cable.
*Note, you will need to bend the outer pins going into the servo cable a little in order to make it fit. See below pic made using pliers for reference.
Repeat the above for one side of all 3 servo cables.
Use a set of 3 double header pins to add pins to the end of the gripper servo wire.
- Wire up the breadboard following the diagram below and keep mind the following useful information
In the below diagram you can have multiple smart servo wires lined up on the breadboard, all wired to the same ports
LX-224 Pinout
Gripper Server Pinout
Brown = Ground
Red = 5v from USB
Yellow = Servo Pulse
Congrats! You've wired up the board. Get Ready to move on to the next step of provisioning the motors.
This section shows how to individually identify the smart servos to the ItsyBitsy's firmware.
While wiring you probably noticed that all 3 motors got the same signal, power and ground. The smart servo cables can be used to connect multiple smart servos to each other in a chain and still maintain individual functionality, provided they have been provisioned. (Think similar to I2C) However due to wire size chaining more than two smart servos together is not reccomended.
While provisioning motors we cannot have multiple motors connects, so remove all connected motors except for one, then plug in the barrel jack power connector and finally plug the usb cable into your computer.
After plugging in the wire click the reset button on the itsybitsy ONE time. You should see a small red led (next to the reset button) flash slowly (on for a second then off for a second).
Protip: during the process or now your red led on your itsybitsy might go from a slow flash to a solid red or turn off. If this happens reset your board by hitting the reset button.
Open a terminal window and type the following command:
putty -serial /dev/ttyACM0 -sercfg 115200,8,n,1,N
Protip: The command will not work unless all power cables are plugged in and led is slow blinking.
Protip: your itsybitsy may not be on the /dev/ttyACM0 port, if you try to run the putty command and the above conditions are met and you still get an error, then go down to the Extras section 7.3 for a tutorial on how to find which port to use. Scroll back up and continue from here after.
If the command runs successfully a black black window will pop up. This is a serial monitor to that allows us to read and send serial data to the itsybitsy
Inorder to verify communication is working type ID in the window and you should get an reply that looks similar to below.
In order to provision the motors we need to use the ID command, it is a very simple command that has two modes typing
ID
will return the ID of the current motor that is plugged in
and typing
ID X
will set the ID of the current motor to X (X being a number).
Go ahead and provision the Smart servos with ID's 1,2, and 3.
Protip: You might need to reset the board between unplugging one servo and plugging in the next.
Protip: Having a sharpie or any other way of marking the motors is useful to avoid confusion during assembely.
After provisioning you can plug in already provioned motors and check them with the ID command.
If all your motors keep their ID's congrats you have successfuly provisoned all 3 motors. Now onto calibration.
Calibrating the motors is an important step, while these servos are continous, they only have 240 degrees of sensing. This means that your motors can be in a position after assembely where they may not be able to be controlled across their entire range. In order to fix this we try to calibrate the motors and check if they are able to reach their entire measurable range before assembly.
To calibrate.
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Plug in all 3 motors and reboot the firmware.
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Open up putty using the same command as you did earlier.
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Press and hold the calibrate button 10 seconeds then let go. The motors should calibrate and move to a calibrated position. If successful you should see the lines:
Starting the motor motion after calibration
Starting the planner
on the putty terminal. If this is not what you see contact an SA or Kevin.
If you have made this far congrats you now have successfuly built a control board, provisioned your motors and calibrated them. Be careful not to turn the output shaft of the servos during the assembly.
Head back to the main instructions to continue with physcial assembly!
ItsyBitsy GPIO-12 to Servo Pulse
ItsyBitsy GPIO-1 to 74hc126 A (see datasheet)
ItsyBitsy GPIO-0 to LX-224 Serial Pin
ItsyBitsy GPIO-9 to 74HC126 OE
74HC126 Y to LX-224 Serial Pin
ItsyBitsy GPIO-11 to Calibrate Switch pin 1
Calibrate Switch pin 2 to Ground
74HC126 Power to 3.3v
Connect all grounds
Barrel Jack 7.5v to LX-224 Power
Running the following command below will tell you each usb device connected to your computer. Replace /dev/ttyACM0 in the putty command with the port connected to your ItsyBitsy.
ls -al /dev/ttyACM*