SWD problem ''Failed to read memory''

daha0902 · ‎2016-02-08

Posted on February 08, 2016 at 13:43

Hi!

I am having problems when using SWD cables to read/write on my STM32F105RC MCU. The MCU is on a custom board. I connect with ST Link Utility but get the error ''Failed to read memory'' 0x080000xx. At each connect it gives error on different memory places.

My cable-setup is:

Pin on MCU:46 SWDIO, 49 SWCLK, POWER, GND.

I know SWD cables is correct due to I have tested the two different F105RC MCU to rule out error on MCU. I have tested both MCU in a external EEprom burner (flash file to mcu also tested - ok).

Possible errors:

No resistor connected to SWDIO/SWCLK

PCB layout error?

BOOT0/1 is not connected from MCU

Connect reset (nReset?)

All help appreciated

Regards

Daniel

I also attach the picture from ST Link Utility if it is not shown in the post.

flash read swd stm32f

Tesla DeLorean · ‎2016-02-08

Posted on February 08, 2016 at 17:48

Do you have a circuit diagram? BOOTx pins just left floating? Any reset circuitry?

Does the behaviour change if you pull-up BOOT0?

Connecting NRST to the debug interface is always strongly recommended, it would permit ''Connect under Reset'' options to be workable.

Consider if the code already on the device puts it into a low power mode, or otherwise changes the GPIO pin configurations.

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daha0902 · ‎2016-02-09

Posted on February 09, 2016 at 16:17

Hi Clive!

Thanks for your ideas to resolve the problem. I do not have a a circuit diagram for this custom board.

I have tried to pull-up BOOT0 and this made no difference.

I tried the Connect under reset with Nreset pin 7 from MCU to ST Link/V2 but no difference.

However, I can skip SWD for now. I need to flash the MCU and I was wondering how to get F105 into DFU-mode via USB to flash via Dfuse? I have tried but the PC recognize the board as unknow device in the device manager but can not get this into DFU-mode. PA10/PA11 goes from MCU to USB on the PCB.

Question: Is it necessary to have PA9/USB_OTG_VBUS connected to +5V?

The MCU is STM32F105RCT6 marked with information:

GH27C 93

CHN GH 522

So, manufactured week 22 - 2015.

I have a HSE 8 MHz on this board. The MCU is new.

Do you have any idea regarding DFU mode? What do I need to do to get this working?

Regards

Daniel