Note: This work is ongoing see the Benito info page for current info…

Click for larger image.

Compared to the the ftdi boards I have been working on the parts count is pretty high but I am banking on flexibility to make it worth while.

Click for link to positive at 600%

For the prototype I used my usual 1.5 sided board technique where the ground plain is brought to the top of the board and the alignment can be off by a couple of mm. The leds are some super bright ones in a plcc4 package that I have several hundred of. The pads in the eagle library for them are HUGE. I turned over the eagle files to Monty Goodson of bittybot.com who has lots of experience at getting things to be small so hopefully the final board will be a lot smaller.

In the mean time feel free to use the Positive image above to create your own board

The Programming Header

At the moment I have a very AVR centric view of the universe. For that reason the programming header that made the most sense was a combination of a serial connection with the 6 pin isp connection. For target boards based on other processors such as the DS5000 and the LP21xxx the SPI pins can be repurposed and the software adjusted accordingly.

Using the built-in boot-loader

When you get power, usb, crystal, reset and hwb wired you can enter the chips usb boot-loader by holding HWB low during reset. If you have a mac like me and look look at the usb section of your system profiler you should see the following:

device AT90USB162
DFU:Version:    0.00
Bus Power (mA):    500
Speed:    Up to 12 Mb/sec
Manufacturer:    ATMEL
Product ID:    0x2ffa
Serial Number:    1.0.5
Vendor ID:    0x03eb

You can now program the chip using Atmel’s FLIP utility if you are running windblows (sic) or Weston T. Schmidt’s dfu-programmer on sourceforge http://dfu-programmer.sourceforge.net/ DFU stands for Device Firmware Update.

Running dfu-programmer looks like this.

$ dfu-programmer at90usb162 erase
$ dfu-programmer at90usb162 flash --debug 20 USBtoSerial.a90

target: at90usb162
chip_id: 0x2ffa
vendor_id: 0x03eb
command: flash
quiet: false
debug: 20
device_type: AVR
------ command specific below ------
validate: true
hex file: USBtoSerial.a90
Validating...3182 bytes used (25.90%)

$ dfu-programmer at90usb162 start

I made the .a90 file from my modifications to Dean Camera’s sample code (to be described later) with the following voodoo.

avr-objcopy -R .eeprom -O ihex USBtoSerial.elf USBtoSerial.a90

Now on top of the blinking lights on the board an entirely different device is attatched to my usb port.

The “Driverless” Serial Device.

The USB standard is a lot about throwing several thousand dollars down so you can play as a member. Fortunately for the rest of us there are a couple of generalized devices that have generic definitions. one is the HID (human interface device) and the other is a CDC communications device under the CDC a class of devices is defined which looks like a modem (ACM). If a device says its one of these and acts accordingly most well developed operating systems will load a generic driver for them and just work. (and then there is windows which still requires a .inf file to load the generic driver).

Atmel’s Code Samples.

As much as I love Atmel’s processors it is a constant source of irritation that their best tools are only made available on the windows operating system. It was nice to see that the sample code for Atmel was available for avr-gcc and I ran it up only to find myself picking through 5 layers of slashes “”. This is not just a preference, it is bad coding. (to quote an old co-worker of mine “Its Rubbish — Bin it!)

So I ran it up made it work and started looking at alternatives.

This lead me to Dean Camera’s MyUSB library. Though it is still in development it is much easier to understand and work with than Atmel’s Code.

crtusb162.o

When compiling Atmel’s CDC code I wound up with a linker error complaining that crtusb162.o did not exist After recommending AVRMackPack for nearly 6 months I thought I had found my first bug. After rebuilding my own version of the tool chain and digging around I found that it is a known bug and should be fixed in future releases. In the mean time the fix is easy. Either copy it from the avr3 directory into your source or link the avr3 directory to avr35 where the linker should find it.

#cd  /usr/local/AVRMacPack/avr-4/lib/
#ln -s avr3 avr35

Building the Firmware with MyUSB

The firmware linked below under resources implements a USB serial port which produces a 2ms *reset pulse instead of DTR. It is based on the USBtoSerial Demo from version 1.3.2 of the MyUSB library. To build it unpack the MyUSB library into your work area. Then under the MyUSB library directory create a directory called Projects and unpack the Benito firmware into the Projects directory. If you have xcode (v>2.4) and AvrMacPack you can open the project and build it. Other platforms will have to adjust the Makefile to match their environment. the “make program” target defined in the make file uses the dfu-programmer utility so you can program the device using its built in boot-loader.

Results:

By using Dean Camera’s MyUSB library I was able to create a serial programmer which plugs into Linux and OSX and it “just works”. I was then able to produce the reset pulse in firmware and it continued to “Just Work”. You can see it above plugged into a modern device RBBA board running Limor Fried’s AdaBoot. I was able to do this in a very short amount of time and while the hardware is slightly more complicated than the ft232 boards the cost at 100 boards is actually cheaper.

Moving Forward

In the photo below you can see my prototype board (both sides) next to an ft232rl based programmer with a .1uf capacitor “auto reset hack”. The board on the bottom shows a programming connection between an at90USB82 and a phillips Arm chip.

On the Atmel side the next step is to implement an STK500 based programmer using the SPI port on the at90USB162. I expect that this will be a fairly easy adaptation however first I may revisit the DS500x chips that I have and figure out the best way to switch between the programming and communication modes. From there it would also be a no brainer to adapt the firmware for the lpc21xx chip pictured above.

Resources

• Benito board rev 5 Firmware
• Benito board rev 5 Eagle Files (benito5.tgz)
• Eagle Library with at90USB162 (at90USB.lbr)
• Dean Camera’s MyUSB library project page (http://www.fourwalledcubicle.com/wiki/Wikka/MyUSB)
• DFU Programmer (http://dfu-programmer.sourceforge.net/)

I sent my son to his mom’s with one of the USB Serial boards I built along with a breadboard, an RBBA a pile of resistors and an led array. I thought about this arrangement and decided that I would try to build a breadboard attached programmer that would not be dangling off the edge of the board and in the way.

I am wondering if this isn’t the way to go with the seminar kits.

Board Positive (link to rev A board at 600%)

I am considering a rev B. The tx and rx are reversed and I think I should put 3 pin headers on the power rails. I am also thinking about putting the 3.3v on the inner rail and the 5V on the outer rail on the positive side.

I also made a couple of these but I am missing something and this one doesn’t work (yet)

I was so happy with the boards I did the other day that I decided to make some small boards for the ft232 so that aidan would have a programmer for his breadboard RBBA. I made 20 of these boards so if anyone wants one they can order the following parts to the group order.

Link to board image at 600%

Q

Ok so its cool to have a programmer (http://www.dorkbotpdx.org/blog/feurig/dorkbotpdx_arduino_programmer) that you can use standalone but what is the best way to know that the bootloader you just burned works?

A You use it.

I thought I would write this up for a couple of reasons. I recently did some work with getting the arduino to work with different hardware and in the process I learned a bit about modding the arduino environment. In particular I want to add the “Adaboot” bootloader to the arduino environment, use the burn bootloader feature which was added to version 0010, and test the bootloaders as I was burning them.

AdaBoot

The Adaboot bootloader is named after Limor Fried (AKA Lady Ada http://www.ladyada.net/) who made several enhancements to the stock Arduino bootloader. It is well described on the Modern Device Companies page http://moderndevice.com/bootloader.shtml and can be downloaded from wulfden http://www.wulfden.org/freeduino/ADABOOT.shtml. Both sell kits and processors which are preloaded with the adaboot bootloader, The board they sell is a less expensive version of ladyada’s boarduino (at http://www.adafruit.com).
This method works well because just like programming in Arduino language a lot of the gnarley details like fuse and lock settings are handled by the environment. The other nice thing is that you know that the bootloader works within the environment because you just tested it using the environment.

Moving the bootloader into place

When you unzip the archive from wulfden http://www.wulfden.org/freeduino/ADABOOT_7J04b.zip you will find the source code and a premade hex file for the 168 which is named “ATmegaBOOT_168_ng.hex” when you find the bootloader that comes with the arduino for the arduino_ng you will find that its also named “ATmegaBOOT_168_ng.hex” but as you can see from the table on modern device they are most definately not the same. So we are going to name our bootloader adaboot.hex and copy it into the bootloader section on our Arduino installation and then add it to the Arduino IDE.

$ cp ATmegaBOOT_168_ng.hex /Applications/arduino-0010/hardware/bootloaders/atmega168/adaboot.hex
$ cd /Applications/arduino-0010/hardware
$ cp boards.txt boards.txt.stock
$ open boards.txt

On the mac this last command will bring up the boards.txt file in TextEdit. Copying the code from the decimillia we will create a section with our new bootloader. (the board itself is not important as long as it has the same crystal and processor).


##############################################################
dorkbotpdx.name=Dorkbotpdx Arduino Kit

dorkbotpdx.build.mcu=atmega168
dorkbotpdx.build.f_cpu=16000000L
dorkbotpdx.build.core=arduino

When you reload your arduino software the new “board” will show up like this.

Burning it using the IDE

Select the new board.

Select the serial port used by your arduino

(I will blog later about why mine shows up as /dev/tty.usbserial-ARDWAYNO)

Attach your programmer

and select burn bootloader from the tools menu.

If all is well it will tell you its done burning the bootloader. Also you will notice that the led on pin 13 says hello (flashes) when you reset the board.

Testing it using the IDE

Now load up the blink program from the examples and push the “upload to I/O board” button.

You should notice that the led pin on 13 flashes while it uploads

If all is well it will tell you its done.

And so will your board.