[Episs]

Today I soldered my first BGA chip in self made SMD oven, actually all this I was making past 3 months and testing it to get right soldering profile for BGA chip soldering and here are results


And this is my oven which I bought in local shop for 60$ and throwed out all electronic that was inside and made my own.

To improve heating I added foil and i got heatinh speed of 1.4 C degrees/second

here is electronic I used to control heating process I used Atmega8535, for 220AC switching I used Triac and for temperature measurement PT1000 sensor
+ RS232 com port for data sending to pc.

This is my self made oven tuning software and all heating process visualization soft (red line is oven temperature (actually it could be 10-15 degrees higher because in tests soldering wire Sn63Pb37 melted in 172C but real melting point is 183.


Wen board will be ready I will start to code Nios II processor.

[Xerxes]

Wow! That is really cool. BGA in DIY device...
Did you use 2-layer board?

[Episs]

yes I used 2 layer board and ordered in local PCB house and made 2 boards for 38$, main Idea of making 2 layers was to test how this chip will solder and how will work FPP configuration. I routed just first 2 lines of balls, and configuration pins + Power pins, this is because trace width is 0.25mm and via size is 1mm so it is max I could rout and I have about 50 Free IOs left for conectivity.

currently I soldered DC-DC regulators to get 1.2V and 3.2V and few other things to just see if fpga is working by JTAG, and found several mistakes in board design like didn't connected PLL Power supply VCCA pin and missed few Pull-up resistors in TDI,TCK,TMS lines ( I thought that it will work without them, but it looks like I will need them).

[Episs]

Today I first got my cyclone III to work, by JTAG now I can program it and do other testings like for configuration.
but I think I will need to make one more PCB where I will correct all mistakes I had in this one.
Major mistake was that I left unconnected VCCA1 pin and I had to drill board under fpga and connect VCCA1 pin to 2,6V supply to get fpga to work, and such drilled board don't suit for testing because connection to VCCA1 pin is weak and unstable + I will need to connect also second VCCA2 pin to same 2.6V and I don't want to drill second hole under fpga,

[guru_florida]

I love it! I have thought of doing the same thing with a toaster oven to get BGA. But for now, for my first large scale FPGA board, I went with Fine Pitch version and will probably switch later. Didnt want to bite off more than I could chew at one time.

[Episs]

This is my second fpga PCB that I made to correct all mistakes that was in previous version + this time I used real 0,4mm VIAs to route middle BGA package pins


here you can see how much IOs I could routed out of BGA256 package in just 2 layer PCB - totally have free 110 IO


When I made this board I started to think about this G-code software and looked at older Ideas of using Large Flash memory where to store Step signal information in raw format (like 16-32bit one step speed for each axis) and I found out that previously when I made bit rate calculations I had some mistakes.
for example if we have 40Khz step rate and 4 stepper motors then each second we need information about 160'000 steps so to store each step value in 16bits we will need 2.56Mbit of memory each second and if I have 8Gb Flash memory then i can record 8000/2,56=3125s/60= 52 minutes I think it will be enough for regular CNC part, previous some year ago When I was researching this kind of solution Flash memory densities was about 1Gb and lower + they coasted more, now densities are larger + grater speeds and lower price so it seams advantageous to use Gb flash memory for step signal storage than making this signal hard math Calculations on FPGA, instead all hard math will be made on PC by EpiCNC soft and then raw data will be loaded in FLASH and motion controller will work with flash data.
So I am building New hardware that will have On board 8Gb flash +USB (AT90USB)+FPGA and I will include 5V buffers for Step/dir signals and Also Buffers for quadrature encoder signals as connectors i will use Ethernet RJ45 8 pin connectors because they are cheap, secure, shielded wires available in any electronic, or PC shop,
Totally new PCB will have 8 RJ45 connectors:
4 for step/dir signals, and 4 for Encoder input.
Each Step/Dir RJ45 connector will have 2 step 2dir and 2 inputs + 5V power, and Ground pins so it gets that by one RJ45 2 steppers can be connected

In FPGA side I will have changes too previously I was making cyclone III configuration Out of parallel Flash and CPLD and when I made and soldered that board I saw that this configuration scheme consumes too much PCB space and uses too much FPGA IO pins, actually because of this configuration I was forced to chose FPGA in BGA256 package, now I decided to use Serial type of configuration using SPI flash memory and as FPGA don't support direct SPI flash configuration I will do it by cheap AVR AT90USB chip it will read SPI flash and make proper signals for FPGA to configure it.
AVR chip will do 2 jobs it will handle USB communication and will configure FPGA+ I could implement some other functionality in AVR .
Previously I used FTDI chip and this was only for USB communication, but now using AT90USB I reduced part count by one chip + compared to previous solution this will consume much smaller space and will require just few FPGA IO pins +it will be cheaper, so New fpga will be in 144pin TQFP package (no more BGA chips)

[Xerxes]

Cool looking board!

However, I wonder what kind of data format you are planning. You don't need data for every step. You would need only for example step rate information at 1kHz update frequency. If you use 32 bits, you need 16kB per second for 4 axis.

[Episs]

Cool looking board!

However, I wonder what kind of data format you are planning. You don't need data for every step. You would need only for example step rate information at 1kHz update frequency. If you use 32 bits, you need 16kB per second for 4 axis.

if by data format you mean FAT,NTFS, then I will not use any kind of format, because I am not using Flash cards like SD,MMC, instead I will solder Flash chip and it don't require any data formats like Flash cards.

about step signals I was thinking to use some data compression algorithm to make something like you say that if step rate information is updating at 1Khz frequency and stepping speed is about 30Khz than in order to write 30 equal step speed 16, or 32bit values I will write something like Stepper motor 1 is making 30steps at speed 30Khz, so you won't be sticked to some constant step information update rate.

I have this Idea long time ago and I even wrote ASm code for ATmega128 few years ago in order to compress LTP port receiving step signals, but I found out that PC is sending incorrect signals I saw it by oscilloscope, but I now that Other friend who use Dos based CNC Softs have higher signal Quality so I think it could be possible to make some digital filter for incoming Step signal and then store it in Flash memory for future playbacks so there are lot of possibilities what can be done when you have proper hardware
flash chip write speed is about 3Mbytes/s.

[GuntisK]

I wonder if there is something working...

[will_mo]

Hi everybody,
I'd like to have the VHDL code for PWM MICROSTEPPING CONTROLLER to drive a bipolar stepper motor.I want to use p-fets on the high side H-briges and N-fets on the low side.
I've XILINX SPARTAN XC3S700A.
I'm completly new in FPGA and have a small basic in VHDL.
Please help me to make it happens.