STM32F103 "BluePill" BOOT0 jumper problem

[spilihps]

So, i bought some of these to do some Arduino-experiments with.

However, the batch i received refuses to enter boot-mode when jumping BOOT0.

After pulling my hair, i noticed that when using the BOOT0 jumper, the pin on the chip only gets around 1,1V. Bypassing this and crudely connecting 3.3 directly to the pin makes it work!

There is a 100k resistor on the way, and it measures OK with the DMM, and it is present on the schematics.. And i have 100k from the jumper "socket" to the chip-pin.

Is this a schematic fault, of which i understand there are some on the "BluePill" Cant find any problem like this though. Tried on 4 boards out of 6 that i received..

Any thoughts?

Thanks!

[Brutte]

My bluepill BOOT0 resistor is 10k (R3). 0V/2.6V on pin.
However, BOOT1 is 100k (R4). 3.2V/3.2V on pin.
So it looks like 100k is inadequate.

[iMo]

R3 and R4 are both 100k, and it should work fine. It could be there is an another issue..
What MCU (part number, ie. CS32F103) you have got on the pcb?

FYI - this is an active forum for BluePill and others

https://mcu.selfip.com

[spilihps]

R3 and R4 are both 100k, and it should work fine. It could be there is an another issue..
What MCU (part number, ie. CS32F103) you have got on the pcb?

FYI - this is an active forum for BluePill and others

https://mcu.selfip.com

Thank you for your response.

I will check if it has a part number on it when i get back home, however i guess it is a copy of a copy!

It is a series resistor, and it seems to be the only thing on the "way".

The series resistor on the BOOTline is 100K but in the datasheet it specifies 10k?
Thanks!

[spilihps]

So, the board does not have any number on it,
However, this is the ebay-link for it:

https://www.ebay.com/itm/STM32F103C8T6-Board-Cortex-M3-3-3V-Arduino-IDE-kompatible-ARM-STM32-ARM-32/253369088499


It would be really interesting to know what is wrong..

[iMo]

Look at the MCU chip marking.
10k - what datasheet?

[spilihps]

STM32F103C8T6

Sorry, datasheet was the wrong definition, it’s ST AN2586 https://www.st.com/content/ccc/resource/technical/document/application_note/6c/a3/24/49/a5/d4/4a/db/CD00164185.pdf/files/CD00164185.pdf/jcr:content/translations/en.CD00164185.pdf#page15

Page 15

[spilihps]

So i could not resist to dig more in to this, i replaced the 100k resistor with the 10k in the ST example, and then it works as it should.

Now, i can see that all the schematics for the BluePill specifies 100k, and i also can see the pictures i can find is 100k, and people seem to have no problem with this..

can this be due to a batch of the chip itself?

I cannot find any information on this specific problem. Just about another resistor, but that is for the USB-functionality..