Unable to activate LDELOAD bit

Wireless Connectivity Ultra-Wideband
1

Hi, currently I am trying to write my own driver on stm32 nuleo-144 F303ZE for dwm1000 using PlatofromIO mbed framework. I have successfully write code for simple read/write register however when trying to activate LDELOAD (2D:06) I realize that I can’t change the bit from 0 to 1. I have done all the step in Table 4 according to the user manual, here is my code:

void initializeLDE()
{
    cs = 0;
    spi.write((PMSC_CTRL0 & 0x3F) | 0xC0); // Write command with register address
    spi.write(0x00);               // Write the sub-index
    spi.write(0x01);
    spi.write(0x0301);               
    cs = 1;

    writeSubRegister(OTP_IF, OTP_CTRL, 2, 0x8000);
    wait_us(150);

    writeSubRegister(PMSC_CTRL0, PMSC_CTRL0_SUB, 2, 0x0200);
    
}

code for writing to register:

void writeSubRegister(char reg, char subIndex, int length, uint32_t data)
{
    cs = 0;
    spi.write((reg & 0x3F) | 0xC0); // Clear bit 6, set bits 7 and 6 to 1 (write operation, sub-index present)
    spi.write(subIndex);            // Write the sub-index

    for (int i = 0; i < length; i++)
    {
        spi.write((data >> (8 * i)) & 0xFF); // Write each byte of the data
    }

    cs = 1;
}

My SPI config:

void initSPI()
{
    spi.format(8, 0);       // Set SPI format to 8 bits, mode 0 (CPOL=0, CPHA=0)
    spi.frequency(1000000); // Set SPI frequency to 1MHz
    readRegister(0x00, 4);  // Read the device ID to wake up the DW1000
}

Result:
000000000000000

When I try writing 0xFFFF to 0x2D:06 (OTP_CTRL):
0111111111111001

PS: I have read User Manual v2.18v LDELOAD , but nothing helped