bluepill schematic and usb issue

[e_ale92]

hi guys,

I want to realize my version of the stm32f103 board, known as blue pill, but I have two little questions for you.
1) is the schematic on the wiki page verified?
I ask because in relation to the usb issue, was suggested to replace the pull-up resistor R10 (4.7k or 10k) with a 1.5k resistor or put an appropriate resistor value (e.g 1.8 kΩ) between PA12 and 3V3, however in the schematics the R10 resistor is connected between PA12 and 5V.

2) is the value in the schematic accurate?
on the web there are several schematic with different value for resistor and capacitor

schematics: http://stm32duinoforum.com/forum/images/c/c1/ ... ematic.pdf


thanks for the help,
alex

[Squonk42]

No, as a rule of thumb: never trust Chinese schematics

On the real board, this resistor is most of the time a 10k value between PA12 and +3.3V.

IIRC, there is also a problem for one missing decoupling capacitor, and the values for the crystal stray capacitors are not correct.

If you need a verified schematic, take a look at our own Bluepill F4 board: it is designed mainly for the STM32F405RGT6, but it can also be equipped with an STM32F103R8T6 (both in LQFP64 package), as they are almost pin-to-pin compatible.

For the full story, check this (91 page long) thread.

[BennehBoy]

I wish some kindly Chinese company would start manufacturing a knock off of that

[e_ale92]

No, as a rule of thumb: never trust Chinese schematics

On the real board, this resistor is most of the time a 10k value between PA12 and +3.3V.

IIRC, there is also a problem for one missing decoupling capacitor, and the values for the crystal stray capacitors are not correct.

If you need a verified schematic, take a look at our own Bluepill F4 board: it is designed mainly for the STM32F405RGT6, but it can also be equipped with an STM32F103R8T6 (both in LQFP64 package), as they are almost pin-to-pin compatible.

For the full story, check this (91 page long) thread.

you are right xD

oh, damn!

so are you saying that I might even use the gerber in that repo and then solder the f103 instead the f405 because all the other components are the same? this is a really good news (for the future)!

[Squonk42]

so are you saying that I might even use the gerber in that repo and then solder the f103 instead the f405 because all the other components are the same? this is a really good news (for the future)!

Yes, almost: there are a few BOM changes required for the STM32F103:
viewtopic.php?f=3&t=4086&p=49041#p49041

And it is working, I tested it:
viewtopic.php?f=19&t=2633&start=890#p50851

Please note that this is the LQFP64 version of the F103, not the standard LQFP48 as in the "original" Bluepill, but you can start from the schematic and replace with the smalelr package, the pinout is very similar.

I may even have some spare PCBs left, contact me by PM.

[e_ale92]

hi squonk, sorry for the late.

thank you so much for the valuable informations! there is no problem to use an LQFP64 F1 instead the standard LQFP48 if there are no problems with the firmware that I have already written (cubemx - stm32f103c8t6).

I need more time to study all your schemes/post because I'm a noob in pcb design, but I'll hope to be able to getting the job done.

I'll sent you a pm in the next few minutes

[fredbox]

Here is a nice video on replacing R10 on the blue pill board. The replacement starts at about the 4 minute mark.