Unable to Download to STM32F103C8T6 Custom PCB

[asking]

Hi,

Please find attached, Below is the schematic which i prepared for custom PCB using STM32F103C8T6 MCU.

But i am unable to enter in download mode. I have tried placing same jumpers for boot mode as in Blue Pill.

Only component i have omited is 32.768 Crystal for RTC. i am not using internal rtc so i have not used in my board.

But does that affect the downloading via USART1 ?

Please advise. tried everything possible but not getting success. This is 1st time i am handling STM32 MCU.

[ONadr.1 · Accepted solution]

I found some problems in the schematic. VBAT should be connected to VDD, VSS2 and VSS3 are not connected, NRST pin should be connected via a 100nF capacitor to VSS. I don't know if this is the source of the problem, but it may cause the MCU to malfunction.

[asking]

VSS2 and VSS3 are internally connected to VSS/GND.  NRST pin was the catch. Due to Wrong footprint our RST pin was continuously grounded hence was unable to download the controller. Also our NRST is not pulled up in Schematic and error has been rectified.

Thanks aton...!!!