STm32 ST-Link Utility Frequency Settings

[Junbo Yi]

Posted on July 18, 2016 at 17:36

One can set different frequency from Target -> Settings -> port.

Does this frequency settings effect the speed of user application or just  for the speed of flash programming via SWD?And how to understand the info from ST-Link below.

If you're trying to connect to a low frequency application , please select a lower SWD Frequency mode from Target->Settings menu.

In my application running at 40MHz for STM32F091, most of boards are loading Flash via SWD at 1.8M, but few had to use lower frequency to connect to target and program the flash. Does this mean those Chips using lower frequency for programming has some default?Thanks.JYI #stm32-st-link-utility-frequency

[Tesla DeLorean]

Posted on July 18, 2016 at 17:52

I think low frequency in this context probably means below 1-2MHz

Do you have pull-ups on the SWDIO, SWCLK or NRST pins? If it auto-negotiates a frequency, and successfully programs, probably not a lot to worry about.

[Junbo Yi]

Posted on July 19, 2016 at 23:35NRST pin has 100K pull up resistor and 0.1uF Cap to ground. No external pull-up and pull-down resistors for SWDIO and SWCLK.The Automatic Mode failed to connect to target.Only selecting 100K frequency will successfully connect to target.But working board can connect to target up to Max Frequency 4M.Thanks.JYI

[Tesla DeLorean]

Posted on July 20, 2016 at 01:43

Well you are going have to analyze your circuit and components as built. I'm not in a position to debug the design.

Start with voltages, look for shorts or opens. Does replacing the CPU remedy the issue?