Part 1

·       Example: Blink it Up: verify and upload, and confirmed the light is blinking.

·       Example4_Serial: change the baud to 9600, verify, and upload.

·       Example4_Serial: switch the serial monitor’s baud speed to 115200 baud, verify, and upload:

after holding the board in hand for 60 seconds, temp increased significantly:

 

·       Example1_MicrophoneOutput:

          switch the serial monitor’s baud speed to 115200 baud, verify, and upload:

         

          Scratch on the board, the sound’s frequency became:

         

 

Part 2

Goal

          Understanding that Artemis can use Bluetooth to communicate with computer in terms of Characteristics; There’re multiple Characteristics, such as float Characteristics and string Characteristics. We can use ble.receive_string(uuid) to receive a known message, but in lots of cases we don’t know if there is a message await us, so it’s better to use ble.start_notify(uuid, notification_handler), which continuously listen to messages from the given uuid.

 

Prelab

Following the instructions in Lab1 course page, running following commands in powershell to get the environment ready:

python -m pip install --user virtualenv

python -m venv FastRobots_ble

For the older computer with both python 2 and 3, use ‘python3’ instead of ‘python’.

 

Once we have the environment, next is activate the Virtual environment by

.\FastRobots_ble\Scripts\activate

And install Juypter Notebook with

          pip install numpy pyyaml colorama nest_asyncio bleak jupyterlab

Then simply put the given codebase into the environment, we are ready to start tasks.

 

·       T1 Send ECHO command

         

·       T2. Programming and use GET_TIME_MILLIS command

  

·       T3. notification handler

After setting up the notification handler, once Artemis send a message, Juypter notebook will immediately receive it and print in on screen; I used 1 if condition to determine incoming characteristic is string or float, another nested if condition for the time stamp and temperature extraction for later tasks.

For example, once CMD.GET_TIME_MILLIS lets the Artemis send the current time “T:215108.0”, Juypter notebook receive and print it.

 

·       T4. Get current time stamps

I implemented a function in ble_arduino to send 100 time stamps. I didn’t choose larger amount of time stamps to avoid running of memory.

And when I sent the commend from python, 100 results are sent back from Artemis:

 

Average data transfer rate = 47.755 strings/s = 334.3 bytes/s

 

·       T5. Get, store, and sent time stamps--SEND_TIME_DATA command

I implemented a function in ble_arduino to send 105 time stamps. I used 15*7 nested loop instead of 105 loop to overcome the Estring size limitation problem: in this case, the length of the Estring tx_estring_value is ensured to be less than 150 before I clear its content;

 

And when I sent the commend from python, 105 results are sent back from Artemis:

Average data recording rate = 52500 strings/s = 420000 bytes/s

 

·       T6. Send time& temperature--GET_TEMP_READINGS

Added a nested if condition to extract time stamp and temperature from the string characteristic. I chose ‘;’ as delimiter because it’s not used in the raw data.

 

Average data recording rate = 3225.8 strings/s = 48387.1 bytes/s

 

·       T7. Compare and Contrast

The first method(sending while reading data) is more than 1000 slower than the second method(recording all before sending data). If the memory of the board is very limited, the first method could be the preferred option; Otherwise, the second method is better since robots’ data are time-sensitive and a faster rate is desired in general.

386kB of RAM means the red board can store 48250 time stamps (assume time is 7 bytes long and delimiter is 1 byte long) or 55143 temperature readings (assume the reading is 6 bytes long and delimiter is 1 byte long).

 

Conclusion, Challenges, and Solutions

1.     When I try to implemented the notification handler, I didn’t realize that the uuid passed into the handler is GATT Characteristic rather than string, and that the way to get the string uuid is to uuid.uuid instead of uuid.uuid(), as .uuid is defined as a property, not a function; after reading forum and asking in Ed, I find these facts, and successfully implemented the notification handler which is able to deal both float and string.

2.     On task 5, my original codes was not able to print out anything except crush the programming and disconnect the board; after printing out values inside the loops, I realized that it’s caused by the 150 transmission length limitation; I resolved that by using a nested loop.

·       Through these tasks, I have successfully built up the Bluetooth connection between Artemis board and computer, enable the GATTCharacteristic data transmission, and found the limitation of Artemis’s transmission speed & storage.