stm32f070 wont connect to st link

[Jesus Perez]

Posted on August 12, 2017 at 03:05

I am connecting a standalone board with a STM32f070 to a ST Link v2, but regardless all my efforts ST Link is unable to detect the MCU and I can not program it, I can not found any information about this issue, it seems everyone has done it straight forward with no issues. I am attaching some pics in how I am trying to connect the device to ST Link, I followed the schematics from ST official site with no results.

I have connected VCC 3.3 to board, I am sure GND is ok and jumper for programming is set.

[juozas]

Posted on February 15, 2018 at 11:35

I have found influence of some capacitance on SWCLK pin on my board connector - by probing with oscilloscope. After soldering 12pF to my board between SWCLK and GND, my STLINK and debug with EMBITZ have start to work perfectly.

[Szymon PANECKI]

Posted on February 15, 2018 at 13:10

Hello Jesus Perez,

I made a review of your schematics. Let me share with you its outcome:

Supply pins

• VDD pins and VDDA pin are connected ok.
• VSS pins and VSSA pin are connected ok.

Reset pin

• Perfectly fine: 100nF between NRST and ground is a minimum needed circuitry.

BOOT pin

• I would suggest to remove R1. Instead I would suggest to insert 10k resistor betwenn J3 and 3.3V.

Capacitors

• Decoupling capacitors are completely missing. Each VDD/VDDA pins needs 100nF connected to ground.
• Additionally please add 1uF capacitor between VDDA and ground.
• Also one 4.7..10uF capacitor common for all VDD pins is recommended.

For more information please refer to

http://www.st.com/resource/en/application_note/dm00089834.pdf

. Below I attach a picture with reference schematics.

Regards

Szymon

[gbm]

Posted on February 16, 2018 at 08:16

To keep the thing simple:

1. Short BOOT0 to GND.

2. Get rid of RESET capacitor.

3. Make sure to put the right supply decoupling capacitors close to VDD/GND pins.

4. Reduce SWCLK frequency to no more than 1 MHz - the most important thing to do.

5. You don't really need the RESET connection to ST-Link. Just make sure you don't change the default functions of SWCLK and SWDIO pins in your firmware.