Introduction
This week's assignment was to assemble and program the Fab Isp. I chose to make brian's circuit, which uses the attiny45 chip instead of attiny44.
fabisp key
board
setting up the Modela with fab modules
The machine n our lab is Roland Modela MDX-20
To set up Modela with fab modules i followed the instructions on the fabacaemy pages. To find the tutorial follow the link here
Milling the board
The next step was to mill the pcb in the machine. I started by doing a test mill on a sacrificial pcb. I noticed the bed of the machine was not flat hence the milling was not even .
milling
first test
I then went on to do my first milling. htis are the parameters keyed in on the fab modules
Fab modules
The first parameters did not work so i keyed in the following parameters
working parameters
I proceeded to mill the board with the roland Modela and a 1/64" bit. To cut out the board i used a 1/32" bit
milled board
cut out board
In order to remove the sediments that were mwde during milling i washed the board with water.
washing
washing
The milled board was now ready for stuffing except for one thing. i needed to remove some copper at the top part of the board. I did this using a scapel.
final
after using the scapel
During soldering i found it helpful to first put solder on all the pads and then start with the smallest parts such as the resistors. The magnifying glass was also helpful since some parts were really tiny.
Soldering
Soldering
Soldering
The stuffed board turned out well and was ready for testing
Stuffed board
Stuffed board
Programming The Board
To program the board i used the MkII programmer and the firmware from the archives.
I first entered the directory that contained the firmware and typed the make command. This command generates a hex file for uploading into the board. (NOTE:During this process i had the solder joint shorted with solder.). I then used the make flash command to erase the chip memory.
I then proceeded to upload the code using the command
avrdude -c avrispmkII -p t45 -u -U flash:w:fts_firmware.hex:i
This command should show you the following results
To disable the reset pin of the attiny45 i used the rstdsbl command
Programming
Testing
To test whether my isp programmer is working i first desoldered the solder joint and plugged the programmer in and typed the command lsusb. This gave me positive results since the device appeared as Multiple Vendors USBtiny device.
Testing
It worked! Now the programmer is ready for use
Problems encountered
- Red light on the programmer when i connected the programmer to the fab isp: This was as a result of forgeting to short the solder joint.
- The device signature not recognised: This was as a result to dry joints and wrong orientetion of the zener diodes. (zener diodes should be reverse biased)
- The device not working as needed after uploading the firmware: Turns out i had used the wrong firmware. I had to use the
make flashcommand to remove it and upload the proper firmware. I also had forgotten to disable the reset pin to ensure the board cannot be reprogrammed again