Subject: STM32H753ZI cannot control PC02 as GPIO or SPI2_MISO functionality.

[QuocBui]

Hi expert, our project is currently in the development stage. We are using the NUCLEO-H753ZI Development Kit for firmware development while awaiting the arrival of our custom board from the manufacturer. The dev-kit employs the STM32H753ZI (LQFP144), which has a slightly different pin configuration compared to the MCU on our custom board STM32H753ZI (LQFP100).

During our development process, we encountered an issue with using PC2_C to control SPI2 (SPI2_MISO), where it consistently pulls low. Despite extensive debugging efforts, including configuring the pin as GPIO and measuring with a logic analyzer, the issue persisted. Upon researching similar cases on the ST Community forum STM32H735V (LQFP100) PC2_C and PC3_C speed and FAQ: Default State of STM32H7 switches connecting Pxy_C and Pxy pads, we realized it might be related to a known issue in the STM32H7 family, specifically a bug in the silicon regarding the PC02 pin.

After reviewing the documentation and conducting tests on our end, we observed that while PC3_C can be controlled as expected, PC2_C cannot be controlled even when manipulating the external pad switches using the provided code:

HAL_SYSCFG_AnalogSwitchConfig(SYSCFG_SWITCH_PC2, SYSCFG_SWITCH_PC2_CLOSE);
HAL_SYSCFG_AnalogSwitchConfig(SYSCFG_SWITCH_PC3, SYSCFG_SWITCH_PC3_CLOSE);

1. We would appreciate confirmation regarding whether this issue is indeed related to the chip itself.
2. Additionally, our custom board utilizes the STM32H753ZI (LQFP100) package, which differs slightly from the package used in the NUCLEO-H753ZI. We would like to know if this package also experiences the same issue.

Thank you in advance for your assistance.

[SofLit · Accepted solution]

From my side I probed CN11/35 on the NUCLEO-H753ZI and there is no issue: PC2_C is toggling.

Could you please check the continuity between CN11 connector PC2_C pin and pin28 of the chip? The continuity test should be done on the connector and not on the PCB.

Are you sure the IO is not damaged by a previous usage?

[QuocBui]

Hi @Andreas Bolsch , here are the values of these registers (0x580244F4, 0x58024554, and 0x58000404) after call: 

HAL_SYSCFG_AnalogSwitchConfig(SYSCFG_SWITCH_PC2, SYSCFG_SWITCH_PC2_CLOSE);

  

[Andreas Bolsch]

Hm, these value are indeed correct. So the problem must be in hardware. Revision 'V'?

[QuocBui]

Hi @Andreas Bolsch, FYI, here is the chip information on NUCLEO-H753ZI Dev-Kit:

[SofLit]

• As I've already suggested, you need to check the continuity.
• You need to confirm if PC2_C was not previously used and therefore broken.

PS: there is no difference between different silicon revisions in term of PC2_C pin.

[Andreas Bolsch]

I'm running out of ideas ... Last resort: Check PC2_C with scope (not LA), AC-coupling, a few mV per Div., and toggle only PC2. If only the analog switch is damaged but everything else is ok, there might still be (albeit small) signal present.

[SofLit]

Hello,

Did you find the issue/a solution?