As I'm first trying with the course provided examples (Neil's codes) I'll run the Python script to read the sensor through a FTDI interface.

After installing both the "TKinter" and "serial" packages for Python 2.7 (the installation depends on each system, in my case Macports) and attemping to run the script I got:

            $python hello.mag.45.py 
             
             
            Traceback (most recent call last):
            File "hello.mag.45.py", line 18, in 
            import serial
            File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/serial/__init__.py",
            line 13, in 
            from serial.serialutil import *
            File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/serial/serialutil.py",
            line 10, in 
            import io
            File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/io.py",
            line 51, in 
            import _io
            ImportError:
            dlopen(/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_io.so,
            2): Symbol not found:
            __PyCodecInfo_GetIncrementalDecoder
            Referenced from:
            /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_io.so
            Expected in: flat namespace
            in
            /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_io.so 
              

During all the previous interactions with AVR IC's we've found different issues, such as signature failures or the chip no being recognized at all. So, to prevent this I first tested the hall sensor board running:

 
              $ avrdude -c usbasp -p t45 
               
               
              avrdude: warning: cannot set sck period. please check for usbasp
              firmware update.
              avrdude: avr device initialized and ready to accept instructions

              reading | ################################################## |
              100% 0.01s

              avrdude: device signature = 0x1e9206 (probably t45)

              avrdude: safemode: fuses ok (e:ff, h:df, l:62)

              avrdude done.  thank you.  
              

So, by checking the backwards the fuses on the online fuse calculator I verified that the IC's fuses have the same settings as the C code, specially the clock (in this case Int. RC Osc. 8MHz) since in many forums I've found that the clock is the one of the main cause of signature issues.

So, once the clock is verified I compiled the C code with the Makefile and uploaded the .hex file using:

              
              $ avrdude -P usb -c usbasp -p t45 -U flash:w:main.c.hex
              
              
              avrdude: warning: cannot set sck period. please check for usbasp
              firmware update.
              avrdude: AVR device initialized and ready to accept instructions

              Reading | ################################################## |
              100% 0.00s

              avrdude: Device signature = 0x1e9206 (probably t45)
              avrdude: NOTE: "flash" memory has been specified, an erase cycle
              will be performed
              To disable this feature, specify the -D option.
              avrdude: erasing chip
              avrdude: warning: cannot set sck period. please check for
              usbasp firmware update.
              avrdude: reading input file "main.c.hex"
              avrdude: input file main.c.hex auto detected as Intel Hex
              avrdude: writing flash (660 bytes):

              Writing |
              ################################################## | 100%
              0.58s

              avrdude: 660 bytes of flash written
              avrdude: verifying flash memory against main.c.hex:
              avrdude: load data flash data from input file main.c.hex:
              avrdude: input file main.c.hex auto detected as Intel Hex
              avrdude: input file main.c.hex contains 660 bytes
              avrdude: reading on-chip flash data:

              Reading |
              ################################################## | 100%
              0.43s

              avrdude: verifying ...
              avrdude: 660 bytes of flash verified

              avrdude: safemode: Fuses OK (E:FF, H:DF, L:62)

              avrdude done.  Thank you
              

NOTE: I'm not doing anything yet with the "...cannot set sck perdiod ..." warning, but here might be some guidance on how to solve it. Also note that this warning might be only related with my out-of-date usbasp programmer.

So, with my classmates we decided that each one of us should have many sensor boards to work with, so each one chose one of the already available boards on the class. My chosen sensor (to mill on the board) is the magnetic field sensor. So, my board's links of interest are:

• A photograph of the complete board
• The board components
• Inner milling traces
• Border milling traces
• C code
• Makefile
• Python script
• Java script
• And a couple of videos (link 1, link 2)