STM32F427II (UBGA176) can not program

[dombog]

Posted on November 06, 2013 at 22:39

Hi Everyone,

I have just finished a project with the MCU STM32F427II but I can not program it. I use the ST-LINK v2 programmer with a 4 wire (SWD).I have check all the connection and I found that the pin (bypass_reg) is floatting in my design not at the Vss. Could it cause my problem?In the past, I have use 144 pin LQFP, 100 pin and 64 pin I have never use this pin before.Thank you, #pragramming-swd-bypass_reg

[Tesla DeLorean]

Posted on November 07, 2013 at 01:09

Can you see ~1.25V on the VCAP balls? If not the regulator is off, you could presumably inject 1.25V at the caps.

A secondary signs-of-life test is to pull BOOT0 high and using either USART1 or USART3 at 9600 8E1 send the hex value 0x7F, and observed a 0x79 response (RealTerm hex mode?)

[dombog]

Posted on November 07, 2013 at 15:49

Thank you clive1.

I have check the Vcap1 and Vcap2 voltage and I read 0V, so I have try to put 1.25V on the caps. But I have got same problem with the ST-link cable can not program my MCU. I have a debug header plugged to USART1 on my board so I have try to put BOOT0 to Vcc on boot up and I have send the caracter 0x7F with Realterm but didn't get the respond 0x79.I don't know if that can induce problem if my pin (bypass_reg) is floatting?So what did you think about that?

[Tesla DeLorean]

Posted on November 07, 2013 at 17:36

So what did you think about that?

I'm not using the BGA package, and have access to the same part documentation you do. In the reference design the BYPASS_REG pin is pulled to ground through a 10K resistor. The regulators are OFF, the pin controlling them is BYPASS_REG