7 ms·

My advisor at Stanford is working on an open-source hardware toolchain to solve these exact problems. The Agile Hardware Center is trying to bring software meth

My advisor at Stanford is working on an open-source hardware toolchain to solve these exact problems. The Agile Hardware Center is trying to bring software methodologies of rapid prototyping and pervasive code sharing/reuse to ASICs, CGRAs, and FPGAs: https://aha.stanford.edu/ https://aha.stanford.edu/

mips_avatar 8y ago
Any tips on getting started with FPGA on custom pcbs?
- phendrenad2 8y ago
  Power requirements are annoying. You need multiple voltages and they need to ramp up in a certain sequence at a certain ramp rate(!). Study reference designs - find a development board that has the same family of FPGA and also has published schematics and board layout (such as Intel and Xilinx official boards). Then just copy their power layout.
- civilitty 8y ago
  What exactly do you mean by "getting started with FPGA on custom PCBs?" Have you made custom PCBs with high density BGAs before? Most non-trivial FPGAs (to me that means you can easily fit a decent softcore processor with space left over for your FPGA logic) will be ball grid arrays and almost impossible to DIY without xray inspection equipment and a reflow oven. You can get what you need for a few hundred $ on eBay if you're patient and lucky but even then, getting to the point where you can solder the chips reliably will take time. If you have the budget for professional assembly, then I would start with a Digilent product that has an available reference design you can copy later. First get used to the FPGA and how it works (they are largely incomparable to a CPU or GPU except for the fact that they both have transistors). Then, design a simpler board with a smaller FPGA and work your way up to the big 500-1k pin chips.
  - specialist 8y ago
    Aside: Have you ever considered a DIY youtube channel? If you, @slededit, others on this thread did something like Louis Rossmann, that'd be fantastic. I've never even seen a dentist's x-ray machine, much less seen it used for DIY design. That'd be amazing to watch. Louis Rossmann https://www.youtube.com/channel/UCl2mFZoRqjw_ELax4Yisf6w https://www.youtube.com/channel/UCl2mFZoRqjw_ELax4Yisf6w (But maybe y'all would dial down the rhetoric from an 11 to a 8 or 9.)
  - slededit 8y ago
    You don't need XRay and your reflow oven can be a toaster oven. I do recommend a cheap microscope and a good pair of tweezers though. With this you can do 0.5mm pitch BGA although that is pushing it. I've made hundreds of prototypes this way. The fear of BGA parts is seriously overblown. The only real expensive part is the finer pitch parts will require tighter tolerances on the PCB which will take you out of the PCB batch services price tier. edit: toaster oven, not toaster
    - jacquesm 8y ago
      Your comment reads as if you equate 'BGA' with 'SMD', a BGA is a ball grid array with up to 1,000 tiny pads that have been pre-dipped in solder. Your toaster isn't going to work.
      - extrapickles 8y ago
        You can use a toaster, but your yield will be poor. Slapping some insulation on the oven and a PID controller will improve things significantly. If you screw up the solder job, you can use a hot air gun to remove the BGA part, reball it (using a stencil, fairly cheap if its a common package), then try reflowing again. If you practice for a few hours on scrap electronics, you can get good enough at it.
      - slededit 8y ago
        BGA is actually easier than leaded SMD parts. The tiny leads tend to bridge easily. With BGA you can be up to half the pitch off and it will center itself. I actually only go for leadless and BGA now because anything else is more of a hassle. It is a bit rude to assume I don't know what a BGA part is.
- moflome 8y ago
  Just had a really good experience using a free online service [0] and using a home made reflow set up. I guess it depends on your end goals of the PCB deployment? [0] https://easyeda.com https://easyeda.com
seanmcdirmid 8y ago
It’s a bit ironic that a decade or two ago, there was a drive to make software development look more like hardware development (as if it were somehow better), but the trend has swung all the way around.
- fjsolwmv 8y ago
  What was this drive?
  - Karrot_Kream 8y ago
    Using contracts, random verification, and formal verification methods to ensure the integrity of software blocks, I believe. There's still dozens of us out there, heh.
    - seanmcdirmid 8y ago
      Not just that, but there was a genuine effort to make programming more like connecting together components on a board.
      - dymk 8y ago
        How was that different than ideas found in object oriented programming?
        Karrot_Kream 8y ago
        There were folks that believe you could instantiate objects graphically, and just connect them together and wire them up. Take a look at Java Spring Beans, which let you describe object instances through XML that either defines an object instance or wires up other instances together.
        test001only 8y ago
        What you are mentioning sounds like LabVIEW (http://www.ni.com/en-gb/shop/labview.html http://www.ni.com/en-gb/shop/labview.html). Incidentally it is widely used in semi-conductor industry.

mips_avatar 8y ago

Any tips on getting started with FPGA on custom pcbs?

phendrenad2 8y ago
Power requirements are annoying. You need multiple voltages and they need to ramp up in a certain sequence at a certain ramp rate(!). Study reference designs - find a development board that has the same family of FPGA and also has published schematics and board layout (such as Intel and Xilinx official boards). Then just copy their power layout.
civilitty 8y ago
What exactly do you mean by "getting started with FPGA on custom PCBs?" Have you made custom PCBs with high density BGAs before? Most non-trivial FPGAs (to me that means you can easily fit a decent softcore processor with space left over for your FPGA logic) will be ball grid arrays and almost impossible to DIY without xray inspection equipment and a reflow oven. You can get what you need for a few hundred $ on eBay if you're patient and lucky but even then, getting to the point where you can solder the chips reliably will take time. If you have the budget for professional assembly, then I would start with a Digilent product that has an available reference design you can copy later. First get used to the FPGA and how it works (they are largely incomparable to a CPU or GPU except for the fact that they both have transistors). Then, design a simpler board with a smaller FPGA and work your way up to the big 500-1k pin chips.
- specialist 8y ago
  Aside: Have you ever considered a DIY youtube channel? If you, @slededit, others on this thread did something like Louis Rossmann, that'd be fantastic. I've never even seen a dentist's x-ray machine, much less seen it used for DIY design. That'd be amazing to watch. Louis Rossmann https://www.youtube.com/channel/UCl2mFZoRqjw_ELax4Yisf6w https://www.youtube.com/channel/UCl2mFZoRqjw_ELax4Yisf6w (But maybe y'all would dial down the rhetoric from an 11 to a 8 or 9.)
- slededit 8y ago
  You don't need XRay and your reflow oven can be a toaster oven. I do recommend a cheap microscope and a good pair of tweezers though. With this you can do 0.5mm pitch BGA although that is pushing it. I've made hundreds of prototypes this way. The fear of BGA parts is seriously overblown. The only real expensive part is the finer pitch parts will require tighter tolerances on the PCB which will take you out of the PCB batch services price tier. edit: toaster oven, not toaster
  - jacquesm 8y ago
    Your comment reads as if you equate 'BGA' with 'SMD', a BGA is a ball grid array with up to 1,000 tiny pads that have been pre-dipped in solder. Your toaster isn't going to work.
    - extrapickles 8y ago
      You can use a toaster, but your yield will be poor. Slapping some insulation on the oven and a PID controller will improve things significantly. If you screw up the solder job, you can use a hot air gun to remove the BGA part, reball it (using a stencil, fairly cheap if its a common package), then try reflowing again. If you practice for a few hours on scrap electronics, you can get good enough at it.
    - slededit 8y ago
      BGA is actually easier than leaded SMD parts. The tiny leads tend to bridge easily. With BGA you can be up to half the pitch off and it will center itself. I actually only go for leadless and BGA now because anything else is more of a hassle. It is a bit rude to assume I don't know what a BGA part is.
moflome 8y ago
Just had a really good experience using a free online service [0] and using a home made reflow set up. I guess it depends on your end goals of the PCB deployment? [0] https://easyeda.com https://easyeda.com

seanmcdirmid 8y ago

It’s a bit ironic that a decade or two ago, there was a drive to make software development look more like hardware development (as if it were somehow better), but the trend has swung all the way around.

fjsolwmv 8y ago
What was this drive?
- Karrot_Kream 8y ago
  Using contracts, random verification, and formal verification methods to ensure the integrity of software blocks, I believe. There's still dozens of us out there, heh.
  - seanmcdirmid 8y ago
    Not just that, but there was a genuine effort to make programming more like connecting together components on a board.
    - dymk 8y ago
      How was that different than ideas found in object oriented programming?
      - Karrot_Kream 8y ago
        There were folks that believe you could instantiate objects graphically, and just connect them together and wire them up. Take a look at Java Spring Beans, which let you describe object instances through XML that either defines an object instance or wires up other instances together.
        test001only 8y ago
        What you are mentioning sounds like LabVIEW (http://www.ni.com/en-gb/shop/labview.html http://www.ni.com/en-gb/shop/labview.html). Incidentally it is widely used in semi-conductor industry.