<>STM32G070 Pit filling (1)– Default dropdown 4 Pins

New series of Italian French semiconductors STM32 micro controller STM32G0 series , be based on Arm Cortex-M0 + kernel , Excellent performance within a strict power budget .
New series means less information , Few debugging experiences are shared online ( At present, there is almost no ); Not like STM32F A series of extensive data and various debugging experience .
Recently due to the need of the project STM32G070 Development and debugging of , Record some problems .

<>PD0/PD2/PB15/PA8 default 4K drop-down

In the project ,PB15 and PA8 Used for key detection , At the same time, it's external 10K Pull-up resistance of , Power on (3.3V) It is found that the voltage of the two pins is 0.9V about ; After ruling out other possibilities , I pulled it out MCU( you 're right , It's so simple and rude ), Pin voltage returns to 3.3V, It's all right . So it seems , The problem is MCU On pin , According to the voltage value , The pin should be pulled down 4K Left right resistance .
End in user manual (RM0454) The cause of the problem was found in :

Bit 10 UCPD2_STROBE: PD0 and PD2 pull-down configuration strobe
Upon power on, internal pull-down resistors on PD0 and PD2 pins are enabled
(connected). Setting this bit disables (disconnects) the internal pull-down
resistors.
This bit is only available in STM32G070xx. It is reserved in STM32G030xx.
Bit 9 UCPD1_STROBE: PB15 and PA8 pull-down configuration strobe
Upon power on, internal pull-down resistors on PB15 and PA8 pins are enabled
(connected). Setting this bit disables (disconnects) the internal pull-down
resistors.
This bit is only available in STM32G070xx. It is reserved in STM32G030xx.

MCU After power on , this 4 By default, pull-down resistance is connected to pins .

<> resolvent

In our application , This pull-down resistor is not required , So you can configure it in the code :
HAL_SYSCFG_StrobeDBattpinsConfig(SYSCFG_CFGR1_UCPD1_STROBE |
SYSCFG_CFGR1_UCPD2_STROBE);
<> extend –UCPD

Here's why 4 Pins will default to the pull-down resistance .

STM32G0 Microcontroller is the first support in the world USB Type-C Specification of general microcontroller . Italian French semiconductor innovative USB Type-C Power Delivery
(UCPD) Interface IP Module integration certified USB Type-C Connector management and PD Protocol processing and microcontroller function , include Arm®Cortex®-M0 + kernel , the height is 512
KB Flash memory and peripherals for , for example ,12 position 2.5 MSPS ADC,2 passageway DAC, Fast comparator and high precision timer .
Up to two integrated on-chip UCPD Interface . Each interface supports USB-C Electricity consumption (SNK), power supply (SRC) Or two roles of electricity and power supply (DRP), And support USB
PD Function options , for example ,PPS( Programming power supply ) pattern , signal communication (CC) Line firmware upgrade and verification messages .

PD0/PD2/PB15/PA8 It happens to be these two UCPD Interface CC Control pin .

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