I’m trying to use CubeProgrammer_API.dll in python to program STM32 microcontroller memory over USART interface.

In general, following operations shall be performed at the beginning:

1. Get list of available serial ports using getUsartList() call (it returns array of usartConnectParameters structures).
2. Start connection to target through USART interface using connectUsartBootloader() call (passing selected usartConnectParameters structure)

CubeProgrammer_API.h

typedef struct usartConnectParameters
{
    char portName[100];             /**< Interface identifier: COM1, COM2, /dev/ttyS0...*/
    unsigned int  baudrate;         /**< Speed transmission: 115200, 9600... */
    usartParity parity;             /**< Parity bit: value in usartParity. */
    unsigned char dataBits;         /**< Data bit: value in {6, 7, 8}. */
    float stopBits;                 /**< Stop bit: value in {1, 1.5, 2}. */
    usartFlowControl flowControl;   /**< Flow control: value in usartFlowControl. */
    int statusRTS;                  /**< RTS: Value in {0,1}. */
    int statusDTR;                  /**< DTR: Value in {0,1}. */
    unsigned char noinitBits;       /**< Set No Init bits: value in {0,1}. */
    char rdu;                       /**< request a read unprotect: value in {0,1}.*/
    char tzenreg;                       /**< request a TZEN regression: value in {0,1}.*/
}usartConnectParameters;

int getUsartList(usartConnectParameters** usartList);

int connectUsartBootloader(usartConnectParameters usartParameters);

So far I’m able to invoke getUsartList() function and receive correct array of usartConnectParameters structures.

script.py

from ctypes import *
dll = cdll.LoadLibrary(r'C:Program FilesSTMicroelectronicsSTM32CubeSTM32CubeProgrammerapilibCubeProgrammer_API.dll')

class usartConnectParameters(Structure):
    _fields_ = [("portName", c_byte * 100),  #  or c_char * 100
                ("baudrate", c_uint),
                ("parity", c_int),  # usartParity
                ("dataBits", c_ubyte),  
                ("stopBits", c_float),
                ("flowControl", c_int),  # usartFlowControl
                ("statusRTS", c_int),
                ("statusDTR", c_int),
                ("noinitBits", c_ubyte),  
                ("rdu", c_byte),
                ("tzenreg", c_byte)]

getUsartList = dll.getUsartList
getUsartList.argtypes = (POINTER(POINTER(usartConnectParameters)),)
getUsartList.restype = c_int
uartParam = POINTER(usartConnectParameters)()
uartCnt = getUsartList(byref(uartParam))

Unfortunately when I’m trying to invoke connectUsartBootloader() function with one usartConnectParameters structure from the list,

connectUsartBootloader = dll.connectUsartBootloader
connectUsartBootloader.argtypes = (usartConnectParameters,)
connectUsartBootloader.restype = c_int
connectUsartBootloader(uartParam[0])

I’m getting an exception:

OSError: exception: access violation writing 0x0000000000000000

Can anyone point me in the right direction or provide some more info on this kind of errors?