More LED Matrix shenanigans!

It's been about two weeks since my last post.   It took a few nights to wire the sparkfun button pads, and a few more days for various parts, but "we have lift-off"!!   The wiring really got stupid, fortunately I had a ton of leftover cuttoff wire from 3d printers! I used some protoboard which connects to the button pads via header / connector, then i wired up R/G/B/Row/Button connectors.   This literally took me 3 sessions of 2-3 hours each.    be patient, tin EVERY wire and double check each joint!

After wiring it all up, I realized I didn't have anything to connect this to my breadboard!  So i ordered some pre-wired 8 pin connectors, and after a few hours of tinkering (mostly trying different wiring schemes mentioned in the code), I had a few blinky lights!

I'd originally encountered the "Demystifying the TLC5940" ebook and code which got me pretty close, but my row scanning setup was slightly different.   A little more googling lead me to nearly exactly what i needed!
https://github.com/jblang/tlc5940demystified

This guy is using a similar shift register setup to select rows.   He's using a shift register / transistor in one combo device.   I'm using 74HC164 which allows you to shift out w/out the use of a latch pin, and that powers TLC59213 to source the current for the LED's.     I ran the clock of the 164 to the clock of the 59213, adjusted some pins in the code and got what you see above!

Now, this is certainly progress, but its not entirely correct. First off, he's only using a Red/Green matrix, I need one more color!   From what I can tell, in his wiring, he's doing R-G-R-G, etc.   He's also only using 1 TLC5940.  On mine, I'm doing 1-TLC5940 for each color - RRRRRRRRRRRRRRRGGGGGGGGGGGGGGGBBBBBBBBBBBBBB..   I found getting this sorted was just a matter of changing some of the math that selects the pins.   A few more quick changes, and I had both his Plasma and Scoll functions working well!

I've made a fork of the above project on GitHub which can be found here:
https://github.com/billieblaze/tlc5940demystified

Next, I'll be adding some of the Adafruit GFX library functionality and integrating my button row scanning!

Post by Billie 'Blaze' Berzinskas.

Programming Attiny85 from Arduino IDE

Now that I can bootload code onto my ATTiny85's, its almost time to get down to some programming!     I do want to get into AVR C **ALOT** more, but also in the interest of maybe getting some participants in the project, I've opted to stick with the Arduino IDE for now.    This poses several issues, namely how to upload the sketch via the recently installed TinySafeBoot!?

I'd already modifed my attiny cores (arduino/hardware/tiny/boards.txt) to create a custom config for setting the fuses before i burned the bootloader (with atmel studio at the time).    It seemed to me, that I could modify the uploader, since the Arduino enviroment doesn't have "external tools" like Atmel Studio.   Unfortunately, this was not the case with Arduino 1.0.5, so I wound up updating to 1.5.6 beta.   I found some information about jeeLabs doing similar stuff w/ Tiny84 (https://github.com/jscrane/attiny) which got me pretty close.  I also did some heavy reading into the Arduino 1.5 platforms spec (https://code.google.com/p/arduino/wiki/Platforms1).   With this, I was able to generate the following bits to allow me to upload to TinySafeBoot from the Arduino IDE: 

BOARDS.TXT

attiny85at8TSB.name=ATtiny85 @ 8 MHz (internal oscillator; TSB Bootloader)
attiny85at8TSB.build.mcu=attiny85
attiny85at8TSB.build.f_cpu=8000000L
attiny85at8TSB.build.core=tiny
attiny85at8TSB.build.variant=standard
attiny85at8TSB.upload.tool=tsb
attiny85at8TSB.program.tool=avrdude
attiny85at8TSB.program.using=arduino:arduinoisp
attiny85at8TSB.program.maximum_size=8192
attiny85at8TSB.program.speed=19200
attiny85at8TSB.erase.tool=avrdude
attiny85at8TSB.erase.using=arduino:arduinoisp
attiny85at8TSB.erase.maximum_size=8192
attiny85at8TSB.erase.speed=19200
attiny85at8TSB.bootloader.tool=avrdude
attiny85at8TSB.bootloader.using=arduino:arduinoisp
attiny85at8TSB.bootloader.speed=19200
attiny85at8TSB.bootloader.low_fuses=0xC2
attiny85at8TSB.bootloader.high_fuses=0xD5
attiny85at8TSB.bootloader.extended_fuses=0xFE
attiny85at8TSB.bootloader.file=tiny85.hex

PLATFORMS.TXT

tools.tsb.cmd=tsb.exe
tools.tsb.path=c:\users\bblaze\desktop\tsb\
tools.tsb.upload.params.verbose=
tools.tsb.upload.params.quiet=
tools.tsb.upload.pattern="{path}\{cmd}" "{serial.port}" "FW" "{build.path}/{build.project_name}.hex" 

I will establish a programming bus to allow me to program multiple slaves soon.   I'm slightly concerned with the bootloader default ports (B0 / B1) because B0 overlaps the I2C pin that I'll be using to communicate with the master atmega328p.     For now, I'm just disconnecting that one line when I need to bootload.

My friend turned me on to the Arduino MasterReader / SlaveWriter sketch (http://arduino.cc/en/Tutorial/MasterReader#.UxJqzvldU5N)  which uses the wire lib across 2 atmega328p.   This is a good conceptual idea of what'll be going on.  Additionally, this instructable gives some good insight into i2c communication between microcontrollers (http://www.instructables.com/id/I2C_Bus_for_ATtiny_and_ATmega/)

  I've got programming capabilities on both master / slave. I've confirmed connectivity.  I've got the basic communication protocol hashed out in my head.   All the pieces are falling into place!

In the next post, I hope to have hashed out the basic schematic and have some workable sample code across a few slaves.

ATMega / ATtiny experiments - Pt2 - Bootloaders

So, last night i was able to get the aforementioned AVR112 application note code (TWI Bootloader) loaded onto my ATTiny slave.  However, for the life of me, I can't get the code onto the master (albeit a different processor then the example).   I finally gave up on that after spending all night and morning on it.

After work, I started playing with a different one "TinySafeBootloader".    This one seems pretty cool, it's able to reprogram itself, basically updating the bootloader itself!   It can also program mulitple slaves on a single programming bus, by using different passwords for each.   Again, I was able to get it going on my slave (I THINK!).  This time, I compiled the assembler file for my particular target and was able to hack up my attiny arduino files to slightly modify the programming fuses and upload the bootloader.    The difference b/w this one and the AVR note is this one works on any two-wire serial bus.   I programmed the bootloader and attempted to send it a sample program via my FTDI breakout...  Nothing..  It doesn't seem to want to connect.   I changed a few things in my arduino boards file and reloaded several times, same thing..      I really like the things it offers, but I've also seen a few people say they couldn't get it to work.  While the documentation is great as far as WHAT / HOW it does what it does, its certainly lacking the implementation details!  

I'm going to hack on it a little bit longer and hopefully see some progress, otherwise - NEEEXXXTT!     More to follow, stay tuned.

ATmega Master / Multiple ATtiny Slave experiments - pt 1

So, I've got this idea for a totally modular synth / controller / whatever environment.   A master ATMega runs an event driven framework and manages any time sensitive operations.   It delegates tasks to a series of "modules" much like Digitial IO, Analog IO, MIDI, Matrix LED, etc. Rather then connecting the master straight to a shift register chain, or some other peripherals,  the functionality would be controlled by the ATtiny slave.  

Why would I want to do this?  Well, I've got several musical related projects (Midi sequencer, wavetable oscillator, midi controllers) and I'd like to reign in the codebase a little.  Each project has many similarities that could easily be abstracted.  I feel the advantages are huge for a few reasons:  

1) UI and other long running tasks don't tie up the more crucial time sensitive bits
2) Modules could become their own standalone gizmos
3) Modules could be interconnected in almost limitless ways

Proposed Core functionality:

• Event Driven framework or RTOS
• MIDI IO with thru / clock sync / clock gen
• Bootload slaves via I2c
• Allow configuration of slave address / role 

Modules will have an address and a corresponding role.   A simple messaging setup should allow a few bits
to delegate any task and value from the core to the slave.  

Proposed modules for V1:

• Analog In  (rotary pots, audio, cv, etc) 
• Analog Out  (i2c dac, audio / cv) 
• Digital In (button / encoders)
• Digital out (led, trigger, etc)
• RGB LED Matrix 
• I2c text and graphical lcds
• Keypad decoding

Phase 1 - Communicating amongst devices
Initially, I'd planned to use a straight up serial bus from master to slaves and use i2c peripherals on the slaves. I POC'd this a little and talked to some friends and it seems the consensus is to use i2c from master-> slave, then SPI or bitbang i2c out from the attiny slaves.    Seems legit..

Phase 2 - The switch from Arduino to AVR.    
All of my existing work is Arduino.   Its nice to an extent, but as i started to delve deeper, I realized I'm going to need the ability to bootload slaves from the master.  While I could recreate the wheel,  I found that Atmel application note AVR112 pretty much nails the requirement here.  A PC runs an application which executes the update from a host microcontroller to a target over "TWI" (atmels name for i2c) or USI.  

I installed Atmel Studio and was able to send a blink program to my attiny by leveraging the arduinoAsISP application I already had loaded on my Arduino Uno.   I setup an "external tool" in Atmel Studio which would execute:

Command: C:\Program Files (x86)\Arduino\hardware\tools\avr\bin\avrdude.exe
Parameters: -b19200  -C"C:\Program Files (x86)\Arduino\hardware/tools/avr/etc/avrdude.conf" -v -v -v -v -pattiny85 -cstk500v1 -P\\.\COM6  -Uflash:w:"$(TargetDir)$(TargetName).hex":i

Now I can simply F7 to build a debug version of my program, and then run the external tool to send it to the AVR..  COOL..  

Well, cool until I got back to the bootloader end of things.    Having a bootloader in this environment seems like a no-brainer! Shuffling ISP wires, or moving chips back and forth to programming devices doesn't sound very fun!   I WANT CODE!  I managed to get the bootloader slave code into atmel studio from the provided .zip from atmel.  I tried to compile it - ERROR!   Apparently, Atmel doesn't use AVR-GCC as a compiler for their example code because its not really a "commercially viable" compiler or something..    I had to download / install the IAR Embedded Workbench to compile them to .hex, which i will then in turn use AVRDude to upload to my target device.  

Hopefully, I'll at least get the bootloader up and functional tonight and my next post, I'll look at getting the master to progam the slave and load another program (blink and led , followed by some introductory communication)






references:

 midibox (http://www.ucapps.de)