STM32F103 "BluePill" BOOT0 jumper problem

• STM32F103 "BluePill" BOOT0 jumper problem
  Posted by spilihps on 09 Aug, 2019 15:43
• 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!
  
• #1 Reply
  Posted by Brutte on 09 Aug, 2019 16:11
• 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.
  
  
• #2 Reply
  Posted by iMo on 09 Aug, 2019 16:25
• 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
  
• #3 Reply
  Posted by spilihps on 09 Aug, 2019 16:47
• Quote from: imo on 09 Aug, 2019 16:25

  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!
  
  
• #4 Reply
  Posted by spilihps on 09 Aug, 2019 21:04
• 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..
• #5 Reply
  Posted by iMo on 09 Aug, 2019 21:51
• Look at the MCU chip marking.
  10k - what datasheet?
• #6 Reply
  Posted by spilihps on 09 Aug, 2019 22:20
• 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
• #7 Reply
  Posted by spilihps on 10 Aug, 2019 13:29
• 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..