STM32F103 "BluePill" BOOT0 jumper problem - Page 1
Forum section: electronics / general

author: spilihps
author_rank: Regular Contributor
timestamp: August 09, 2019, 03:43:41 pm
content: 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!

author: Brutte
author_rank: Frequent Contributor
timestamp: August 09, 2019, 04:11:32 pm
content: 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.

author: iMo
author_rank: Super Contributor
timestamp: August 09, 2019, 04:25:00 pm
content: 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 othershttps://mcu.selfip.com

author: spilihps
author_rank: Regular Contributor
timestamp: August 09, 2019, 04:47:50 pm
content: Quote from: imo on August 09, 2019, 04:25:00 pmThank 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!

author: spilihps
author_rank: Regular Contributor
timestamp: August 09, 2019, 09:04:27 pm
content: 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-32/253369088499It would be really interesting to know what is wrong..

author: iMo
author_rank: Super Contributor
timestamp: August 09, 2019, 09:51:25 pm
content: Look at the MCU chip marking.10k - what datasheet?

author: spilihps
author_rank: Regular Contributor
timestamp: August 09, 2019, 10:20:16 pm
content: STM32F103C8T6Sorry, datasheet was the wrong definition, it’s ST AN2586https://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#page15Page 15

author: spilihps
author_rank: Regular Contributor
timestamp: August 10, 2019, 01:29:21 pm
content: 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..