![]() But get one without acetone, as it can damage some plastics). Remove the solder residues this method leaves all around (nail polish dissolvent and a toothbrush work as good as flux cleaners, and is a lot cheaper. Then, using solder wick, remove the excess solder which should go away easily, leaving just enough solder on each pin. Once the part is correctly placed, make solder bumps on all pins, shorting them all together. If they are not, melt the solder and carefully move the part. Double check all pins are correctly placed on their corresponding PCB pads - it will be very difficult to correct an error afterwards. First, prevent the part from moving using approximately the same technique as before : place the part very precisely using your hand or a pair of tweezers, then make a drop of solder on a couple of neighbouring pins (you don't care if you short them). ) you would go mad trying to solder each pin individually while avoiding short-circuits (and not heating the part too much !). ![]() For SMD parts with a lot of small pins (ie.Then, solder the other end of the component (be careful not to heat too much, not only you may damage the component but also you risk melting the first solder holding it), and rework the first solder.ĭont't mess around with SMD glue, it's a complete waste of time and money compared to this technique. You don't care if the solder is not good, its only purpose is to prevent the part from moving. Then heat it with the iron while plunging one pin of the part in the melted solder ball, with a pair of tweezers. resistors, capacitors, small SOICs.) first make a solder ball on one of the PCB pads. For SMD parts with a low pin count (ie.A TQFP-144 can be soldered in about 10 minutes with very little equipment ! The board depicted above was entirely soldered by hand using an off-the-shelf soldering iron and a bit of inexpensive solder wick. SMD solderingIt's a common myth that soldering small SMD parts such as TQFPs require lots of equipment. one 26-pin connector on the bottom is for connecting the probes (or whatever device you fancy -). #Fpga projects altera cyclone ii serialone 10-pin connector on the bottom is for connecting a serial FPGA configuration device.Its pinout is the same as on Altera development boards, so you can directly use Altera Byteblaster cables for instance. one 10-pin connector on top of the board is for JTAG configuration of the FPGA.The board is equipped with three connectors : Bit 16 of the NET2272 bus is not connected to the FPGA (the NET2272 can operate in 8-bit mode anyway, but it's slower).Īlso, Actel FPGAs seem better for this kind of project, but I went with the design tools I had available at that time.The wiring of the USB plug is incorrect, pin 5 is GND (not shield) and pin 4 can be left unconnected.IN EVERY CASE, DOUBLE-CHECK POWER SUPPLY VOLTAGES BEFORE SOLDERING THE FPGA AND THE NET2272 ! The switching regulators need additional 100nF decoupling capacitors close to their input pins, or they can go unstable.If you choose to replicate this device, please note there are a few stupid design errors in the files provided here (fortunately, they can be corrected with little board rework) : The 3.3V supply is also converted to 2.5V by a linear regulator, and used to supply parts of the NET2272. The 5V from USB is converted to 3.3V (used by the NET2272 and FPGA I/O) by a LTC3411 switching regulator and to 1.2V by another LTC3411 regulator (used by the FPGA core). The FPGA was programmed with a mix of VHDL and schematic diagrams, and includes a minimal USB protocol handler entirely in hardware (no softcore processor was used). Technical descriptionThe board uses a small Altera Cyclone II FPGA (EP2C5T144C7N) and a NET2272 USB controller from NetChip (this part is a bit hard to find, I got mine from Mouser Electronics). ![]() (Thanks PCB-Pool for providing the circuit board) But as this board is FPGA-based, it can be used for any application requiring a high transfer rate (hundreds of MBit/s) with a computer. The purpose of this board was to sample a reasonable number of logic channels (24) at a high rate, and stream the data to a computer through high-speed USB 2.0. ![]()
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