FabLab Academy 2012

Manchester Lab

David Forgham-Bailey

Week  11: input devices

The assignment this week was to measure something - add a sensor to a microcontroller board and read it.

I decided to make all the example boards to investigate the different sensors, and evaluate which whould be appropriate for my final project.

When starting to mill the boards with the Modela the results were very poor - part of the first board was not milled.

I decided to change the bit - I also ended up refitting the sacrificial base plate.
Below shows a comparison of the bits under a microscope -
1/64th  End Mill bits - under microscope to show worn tool:

mill_bit_1         mill_bit_2

Completed boards: button/temp/mic/light/load/TxRx


Each board was programmed by compiling the c file using -

'sudo make -f hello.button.45 make'     (substitute button with: temp/mic/light/load/load/txrx)

and the board programmed by connecting the fabisp board -

'sudo make -f hello.button.45 make program-usbtiny'     (substitute button with: temp/mic/light/load/load/txrx)

The Fabisp was then disconnected and the FTDI cable was used to connect the board to my computer via the usb.
To find out the FTDI port address type: 'ls /dev' in terminal - FTFAZYNF

To read the output using Python Ptinker type:
'python term.py /dev/tty.usbserial-FTFAZYNF 9600' - or -
'python rx.py /dev/tty.usbserial-FTFAZYNF 9600'  -  in terminal

 Button: term.py/ rx.py - should read 'd' when pressed/ 'u' when not pressed: not always accurate with spurious characters being output...

button  button_2

Temp: reading 181.6 at room temp/ 993.9 when touched with finger:

temp  temp_2

Mic: showing response to whistle (single tone):


Light: showing response 381.1 to ambient light/  808.4 to shade

light  light_2

Step (TxRx): showing response 6234 open/ 32806 touched

step  step_2

although each board gave an output the value od the result was not calibrated.