Source code available at https://github.com/ambrogio-galbusera/gr0g, https://github.com/ambrogio-galbusera/gr0g-ble-android and https://github.com/ambrogio-galbusera/gr0g-ble

In this post I will start to play a little bit with the Gertbot board

Preliminary operations

Besides the "typical" tasks you have to work out when you boot a Rapsberry Pi for the first time (like, for example, expanding the filesystem, updating software components etcetera), there are a couple of other things to make the Gertbot board work properly

Disable serial console and enable UART

The internal serial console must be disabled to free the serial port for the Gertbot (as a matter of fact, Raspberry Pi communicates with the Gertbot board using the UART0, which is typically used as a Linux serial console).

By default the serial port on the Raspberry PI is configured for console input/output

To disable Linux serial console and enable UART, you have two options. The second option is actually less straightforward, but I like to understand what happens behind to scene and maybe someone could be interested as well

run raspi-config, navigate to Interfacing options, then Serial.

When asked if you want to be able to access from a serial console, select No, When asked if you want to enable serial hardware, click Yes

Open /boot/cmdline.txt and edit it to disable boot info being sent to the port.

sudo nano /boot/cmdline.txt

Remove the following string from the kernel command line

console=serial0,115200

Save the file with CTRL-O and CTRL-X to exit nano.

Edit file /boot/ config.txt

sudo nano /boot/config.txt

and append a new line at the end of the file

enable_uart=1

Save the file with CTRL-O and CTRL-X to exit nano.

Disable Bluetooth

Bluetooth may use UART port, so it's a good idea to disable it completely. To accomplish this, edit /boot/config.txt

     sudo nano /boot/config.txt

and append

     dtoverlay=pi3-disable-bt

Reboot the board

sudo reboot

to apply the changes

First application

I created a simple application to test PWM output. I connected a 12 Volt power supply and a fan

Then I downloaded the Python library from

https://www.gertbot.com/gbdownload/rev2.8/python_code.tgz

and untared the file

tar xzvf python_code.tgz

There are many samples included in the tgz file, but I will create a very simple application to get familiar with the library itself

I created a new folder for my application, and here I copied file gertbot.py from the folder where the library archive was extracted. Finally, I created a simple application

In this application, I simply

initialize the output

          gb.set_mode(board,channel,gb.MODE_BRUSH)
          gb.move_brushed(board,channel,gb.MOVE_B)

set the PWM frequency and the duty cycle to vary fan speed

          gb.pwm_brushed(board,channel,freq,dc)

switch off the PWM

          gb.set_mode(board,channel,gb.MODE_OFF)

Here is the result (I hope the fan speed is visible in the video)

Hooray! Another step in this challenge!

As soon as my local warehouse will have a 1/4 inch female Tee available, I will start testing the compressor and the atomizer. In case of delays, I will make the final touches to the box or install the LED

BTW, I created a github repository where I will push all the source code I will develop for this challenge. The repo is here

https://github.com/ambrogio-galbusera/gr0g