Troubleshooting Bootloader Access on Nucleo L476RG Using Nucleo L496ZG as Master

DigitalOut extBoot0(D7);
DigitalOut extBoot1(D6);
DigitalOut extReset(D5);

Serial usart(/* tx, rx */ D1, D0);

uint8_t rxBuffer[1];
event_callback_t serialEventCb;

void serialCb(int events) {
    printf("something happened!\n");
}

void initBootloader() {
    wait(5); // just in case?
    // Once initialized the USART1 configuration is: 8-bits, even parity, and 1 Stop bit
    serialEventCb.attach(serialCb);
    usart.format(8, SerialBase::Even, 1);
    uint8_t buffer[1024];

    // write 0x7F
    buffer[0] = 0x7F;
    usart.write(buffer, 1, 0, 0);
    printf("sending cmd\n");
    // should ack 0x79
    usart.read(rxBuffer, 1, serialEventCb, SERIAL_EVENT_RX_ALL, 0x79);
}