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| STM32F103 min system with USB-TTL converter? |
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| ataradov:
I don't think the problem is with bypass capacitors or the layout of the board. I'm pretty sure, if there is a problem, it is in the schematic or soldering. Another problem with capacitors is their actual placement. While it is OK to leave some space for ease of soldering, they must be located on a shortest path from each VDD pin. They won't do anything if they are neatly placed in a row in the corner of the board. So lets start with a cleaned up schematic. Those are power ports and it looks like a correct symbol. Redraw the schematic using them, and we'll from there. |
| bjdhjy888:
Thank you. I have another question for pouring the copper. https://www.novatel.com/assets/Documents/Papers/OEM7700-Product-Sheet.pdf In the above link, you will see a pic of NovAtel's board, on which it features its copper at its four corners and on its two upper and lower sides. Note that there are no green pastes covering these specific areas. The copper basically covers all its rims and via's. They look cool and I guess their purpose is to eliminate noise or interferences. Correct? No to mention the dots(via's?) on the copper for the same purpose? My question is, how do you make such feature with Altium Designer? Would I be able to acomplish such work with the software? I did not see such function in the software. Does anyone have any clues? Thanks. |
| ataradov:
The opening is to ensure contact with the metal case or mounting chassis. This is done for EMI reasons, but this design is far too low speed to worry about that. I don't know specifics for Altium, but generally all you need to do is modify solder mask polygon to whatever shape you want to keep open. Via stitching in this case looks like it was done manually by simply dropping a lot of vias. But I'm sure Altium has tools to do that automatically, since even KiCad does. This is more useful for your design, but again, not really critical. Just place a few vias here and there along the ground planes and you will be fine. |
| Psi:
--- Quote from: bjdhjy888 on January 29, 2019, 12:51:45 pm --- --- Quote from: Psi on January 29, 2019, 11:54:53 am ---Ok, one thing i will say. Ya should wire the ft232rl 3.3v output pin to vccio instead of using 5V from USB. Then TX/RX are 3.3V level and will match the STM32 I can't recall which pins on STM32 are 5V tolerant. But if the pin you're using for TX is not 5V tolerant it will backfeed 5V onto the STM32 VCC and this will cause major problems Also please correct all the SCH pin names to match the actual IC pins. I assume you just repurposed some other sch component? There's lots of stuff in that SCH that i have no idea what it's doing. --- End quote --- So you are saying this is wrong? (I followed this pic I got from the Internet) --- End quote --- There's multiple ways to connect power to a FT232RL depend on what your connecting the chip to. Put simply... The way you have it the FT232RL core runs at 5V, so all its outputs are 5V. If you have a 3.3V processor they usually don't like 5V on their inputs, so the FT232RL provides an onboard 3.3v regulator. To use it you feed the 3.3v output pin into VCCIO. This makes the FT232RL core run at 3.3V and so all the outputs are all 3.3V to match the STM32 inputs. |
| Doctorandus_P:
Why do you not simply buy some ST-Link V2's from Ali / Ebay / China? These cost less than a the FTDI chips and you can not only program the STM32 with it, but you can also use them for debugging. The hardware of these is also just a STM32 in a nice small aluminum USB stick format. You can pull the aluminimum tube off to look what's inside (and for re-programming etc.). Unfortunately there are some different variants of these, and not all have the same quality. Most of these can also be re-flashed with the "black magic probe" firmware to increase their capabilities, but I haven't yet seen a need to dive into this. |
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