Electronics Production
Making the ISP
I used ATtiny44 microcontroller as programmer for FabISP. I followed this document to program the firmware.
I follow this guide to make a FabISP http://fab.cba.mit.edu/content/archive/projects/fabisp/
This is the PCB board:
I used FlatCam software to open the gerber files. I selected the copper top and profile layers.
To make the FabISP board I chose this 3.175 mm shaft diammeter , 20ยบ angle (according to the manufacturer), 0.5 mm cutting diammeter V-shape mill.
Then I changed some parameter on FlatCam for milling the PCB. 20 degrees angle was configurated, v-tip so close to 0.5 because I need for milling the copper 35 microns.
Then, I saved the changes for generating the paths, g-code file.
Similar configuration for the profile cutting, but I used a standard milling tool.
Tool diammeter and speed was changed for profile cutting. A little gap was configured for easy removing the board.
Next, G-code file was generated!
Then, I used MACH4 for controlling the machine.
It shows the gcode lines and the paths for milling. Then, Cycle Start Gcode button was pressed to start milling!
Milling the PCB
I used a miniCNC router to milling the PCB.
My setup is:
Machine: Generic MiniCNC 3040
Controller: MACH4 (Lifetime Licensed)
Speed: 24000 RPM Spindle
Mill: v-shaped engraving bit 0.5mm
Process start
We use masking tape to fix the pcb on the platform
Finishing the milling
Components used
01 x ATtiny44 SMD
01 x miniUSB connector
02 x resistor 1K ohm
01 x resistor 499 ohm
02 x resistor 49 ohm
01 x resistor 499 ohm
01 x green LED
01 x red LED
01 x USB Type A
01 x jumper 02x03
01 x jumper
02 x zener diode 3.3V
01 x capacitor 100n
Components ready to solder
I have performed several tests to determine a good result.
It is very important that before welding we verify that there are no short circuits and verify The width of the track corresponds to the design.
I chose this board, the FabISP 2017, because I have those components in the Fab Lab inventory, because due to a logistics problem it would take too long to arrive.
Perhaps I would have had to redesign the board to use another type of connector.
Connecting board to the PC
When the board was connected to the PC through USB port, a new devide was detected. It means missing driver.
Then, I downloaded the USBTiny (Adafruit) driver for this device. This is the link: https://learn.adafruit.com/usbtinyisp/drivers
Then, I clicked on the link to download it. (adafruit_drivers_2.5.0.0.exe)
Next, I've installed the drivers.
Then, the FabISP is correctly installed.
Testing the FabISP
I used this FabISP to program a Attiny85 PCB to make a led sequence. I used my old PCB for test purposes.
For programming I used the ISP connector.
The FabISP works!
Problems and solutions
*The PCB board is often not completely flat, this was solved by applying masking tape to fix it better.
*The MACH4 software interface may seem a little complex, however, it only requires configuring some important parameters for its correct operation.
Download
Download files
Takeaways assignment:
- Because I am in another campus of the university, I did this activity alone.
- In this assignment I was able to verify how easy and fast it is to make an ISP-type programmer. However, unlike DIP boards, there are some considerations to be taken when making SMD boards.
- I think it is very important to have a programmer to program microcontrollers in general using ISP in any type of project.
- For me it helps me to make modifications and firmware updates quickly