| Electronics > Projects, Designs, and Technical Stuff |
| Sencore USB Interface Project |
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| pigrew:
Another round of updates, though only minor tweaks. I changed to a full size USB jack and added a jumper to go between (Sencore Earth + USB_SH) instead of (Sencore Earth + GND) nets. I've also adjusted the USB series resistors to be 0-ohm instead of 22 (STM32 has internal 40 ohm drivers). I also changed the STM32 programming header pins to suit the layout better (It's not a standard pinout). (To view the 3D PDF, usually I have to use Acrobat and click at button at the top of the window to "trust" the document.... Is there a better way to transmit 3D models for mass consumption?) |
| coromonadalix:
Hi im back sooner Is it possible to use tqfp packages for the machx02 chip, thoses qfn packages are a pain to work, will you assemble the pcbs ? normally you need stencils and a very fine solder paste for them, i work with the same 32 pins package, if you need to rework them or unsolder them, you absolutely need an hot air station, the under center pad dissipate lots of the needed heat into the pcb. For J1 pcb output to the LC102, i would use the same mta100 connector, or any 0.1" pitch connector, it would be easier to make a bridge connector between your interface and the lc102, i have thoses tools at my job, i could make many cables for you or even use already made dupont male to male wires, or maybe an idc10 connector, or a 2x5 pins 0.1" header ? my 2 cents I would have put your 4 holes at the corners, not in the center, but you had an enclosure in mind if i recall, that way U10 would be pushed more in the center of the pcb, shorter pcb traces ?? |
| pigrew:
--- Quote from: coromonadalix on August 25, 2019, 12:04:12 am ---Is it possible to use tqfp packages for the machx02 chip, thoses qfn packages are a pain to work, will you assemble the pcbs ? normally you need stencils and a very fine solder paste for them, i work with the same 32 pins package, if you need to rework them or unsolder them, you absolutely need an hot air station, the under center pad dissipate lots of the needed heat into the pcb. --- End quote --- The smallest TQFP has 100 pins, so much more board space. I decided to use the QFN32 since it comes in two convenient sizes (256 and 1200 LE) and has enough pins. If JLCPCB doesn't remove the solder mask between pins, they are not too difficult to solder. --- Quote from: coromonadalix on August 25, 2019, 12:04:12 am --- For J1 pcb output to the LC102, i would use the same mta100 connector, or any 0.1" pitch connector, it would be easier to make a bridge connector between your interface and the lc102, i have thoses tools at my job, i could make many cables for you or even use already made dupont male to male wires, or maybe an idc10 connector, or a 2x5 pins 0.1" header ? --- End quote --- It's a hard choice. I want some sort plug with strain relief. The Phoenix Contact ones are certainly not ideal, but I'm having trouble convincing myself that some other connector is appropriate. DIN-7 is too large for the enclosure I selected, mini-din8 might be too low voltage? (Even though I'm focusing on isolation, there shouldn't be much of a voltage differential in practice. I just really don't want to fry the computer). But, now I'm leaning towards DE-9 (a.k.a DB-9). It's shielded, has higher voltage ratings, cheap, and somewhat easy to assembly. --- Quote from: coromonadalix on August 25, 2019, 12:04:12 am --- I would have put your 4 holes at the corners, not in the center, but you had an enclosure in mind if i recall, that way U10 would be pushed more in the center of the pcb, shorter pcb traces ?? --- End quote --- Yeah, I'm designing the PCB around the Hammond 1593J enclosure. I don't really like the locations of the mounting holes, but they are where they are... |
| coromonadalix:
The db9 may add confusion, people may think its an serial port ??? Or an idc10 angled connector with latches ?? https://www.futurlec.com/Connectors/IDCMHL10RApr.shtml |
| pigrew:
I've ordered a set of 5 PCBs with a final design. I realized the microcontroller is TTL-level (not CMOS level), so I am able to use a simpler bus level translator IC, instead of a separate input and output IC. This frees up a few FPGA I/O pins, allowing the layout to be more compact and the addition of a debug LED. I did use the DE-9 connector, and am planning to plug one pin to prevent RS-232-level signals from being connected, although the ESD TVS Zeners (and series resistors) may prevent damage to the components. The USB-UART bridge will uses a STM32F052 MCU. My current plan is for it to be a CDC device, but I may eventually implement USBTMC so that it interacts with instrument control software more nicely. Schematics and PCB data files are posted. I missed tweaking the locations of a few designators, but have not found any serious mistakes (yet). Seems I used an unregulated isolated DCDC converter; I'll need to regulate its output, switch converters, or add a resistive load (~150 mW)... (If anyone wants a build (or a kit), I should be able to sell you one once I test the software/design, though I won't offer any sort of warranty. Send me a PM and we'll work something out. Software will put put on github once the hardware is built.) |
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