OQArduino Hacking

Entry: Platform for Sound Lab
Date: Fri Aug  3 15:17:32 EDT 2012

I'm thinking about switching to Arduino to make the sound lab more
accessible.  Staapl PIC stuff could be a sidekick, possibly in the
form of pre-programmed synth chips, but should not be placed in a
the critical path.

The idea is to teach:
- Basic uC stuff on Arduino
- Working with a chip API through SPI/I2C.
- Some analog electronics


Entry: Arduino on debian
Date: Fri Aug  3 16:38:41 EDT 2012

apt-get install arduino

Get:1 http://ftp.be.debian.org/debian/ wheezy/main arduino-core all 1:1.0.1+dfsg-4 [717 kB]
Get:2 http://ftp.be.debian.org/debian/ wheezy/main arduino all 1:1.0.1+dfsg-4 [1,123 kB]

Start it once and let it add your user to the dialout group.  After
that, you need to log in again for the changes to take effect.

Edit the configuration file .arduino/preferences.txt and change this line:
serial.port=/dev/ttyACM0


Entry: Makefile
Date: Sat Aug  4 16:03:28 EDT 2012

Next step: I want to know how it works.  Tried this[1] but it doesn't
work with 1.0 arduino version.  Switching to [2] + made some
modifications.

[1] http://www.arduino.cc/playground/Learning/CommandLine
[2] http://www.kerrywong.com/2011/12/17/makefile-for-arduino-1-0/

Entry: avrdude on the Arduino UNO
Date: Sat Aug  4 20:02:54 EDT 2012

This worked for me, copied from [1].

avrdude -F -V -c arduino -p ATMEGA328P -P /dev/ttyACM0 -b 115200 -U flash:w:main.hex 

[1] http://balau82.wordpress.com/2011/03/29/programming-arduino-uno-in-pure-c/


Entry: Resetting using DTR
Date: Sat Aug  4 20:04:45 EDT 2012

stty -F $(AVRDUDE_PORT) hupcl
perl -MDevice::SerialPort -e 'Device::SerialPort->new("$(AVRDUDE_PORT)")->pulse_dtr_on(1000)';


Entry: Next
Date: Sun Aug  5 18:51:28 EDT 2012

So.. I feel a bit comfortable with what's going on after tinkering
with the Makefile.  Next step is probably to read the ATmega328P
datasheet.


Entry: ATmega328P
Date: Sun Aug  5 18:59:03 EDT 2012

- 32 8-bit registers (memory mapped to 00-1F)
- 3 16-bit index registers (using 6 of the 32 8-bit registers)
- call stack is in SRAM, SP in I/O space
- 234 byte I/O space (memory mapped to 20-5F + 60-FF)


( For a procedural forth the 3 indirect registers would be a/b
pointers and datastack.  There is probably enough register space to
make it 16 bit. )

Entry: ATmega328P (Arduino UNO) + avrdude
Date: Mon Aug 13 21:02:40 EDT 2012

Trick is that my UNO has a m328-pu and not a m328p.  Forcing it works:

sudo avrdude -c usbtiny -p m328p -F -U flash:r:test.bin:r


[1] http://arduino.cc/forum/index.php?topic=58670.0


Entry: AVR I/O pins
Date: Fri Aug 17 14:50:42 EDT 2012

AVR I/O pins config is a bit different than PIC's.

From ATmega328P data sheet, table 13-1:

                PUD
DDxn PORTxn (in MCUCR)   I/O  Pull-up Comment
 0     0         X      Input   No    Tri-state (Hi-Z)
 0     1         0      Input  Yes    Pxn will source current if ext. pulled low.
 0     1         1      Input   No    Tri-state (Hi-Z)
 1     0         X     Output   No    Output Low (Sink)
 1     1         X     Output   No    Output High (Source)

Independent of the setting of Data Direction bit DDxn, the port pin
can be read through the PINxn Register bit.