Troubleshooting Bootloader Access on Nucleo L476RG Using Nucleo L496ZG as Master

Good day guys, I need some help in troubleshooting an issue I'm having with accessing the bootloader on a Nucleo L476RG "slave" board?

I'm using a Nucleo L496ZG as the master board, with

DigitalOut

DigitalOut

pins (

extBoot0

extBoot0

and

extReset

extReset

) connected to the slave's

BOOT0

BOOT0

and

NRST

NRST

pins. There's also a

Serial

Serial

instance (

usart

usart

) on the master linked to the slave's UART2. It appears that

BOOT1

BOOT1

is fixed low, so the bootloader runs instead of executing what's in SRAM.

In

resetToBootloader

resetToBootloader

, I set

BOOT0

BOOT0

high, pull

NRST

NRST

low for 0.1 seconds, then bring it back high. This resets the slave and stops the program from running.

In

initBootloader

initBootloader

, I set up serial communication (8-bit data, even parity, 1 stop bit per AN2606) and send

0x7F

0x7F

to the slave, but there's no response. The logic analyzer shows the slave receives the data, but its TX line remains inactive.

What additional steps might be necessary to successfully start the bootloader? Below is the relevant portion of my code:

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);
}

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);
}

If it's helpful, I can provide a picture of my board setup as well.

DIIS

DevHeads IoT Integration Server•2y ago

Sterling

Troubleshooting Bootloader Access on Nucleo L476RG Using Nucleo L496ZG as Master

Good day guys, I need some help in troubleshooting an issue I'm having with accessing the bootloader on a Nucleo L476RG "slave" board?

I'm using a Nucleo L496ZG as the master board, with

DigitalOut

DigitalOut

pins (

extBoot0

extBoot0

and

extReset

extReset

) connected to the slave's

BOOT0

BOOT0

and

NRST

NRST

pins. There's also a

Serial

Serial

instance (

usart

usart

) on the master linked to the slave's UART2. It appears that

BOOT1

BOOT1

is fixed low, so the bootloader runs instead of executing what's in SRAM.

In

resetToBootloader

resetToBootloader

, I set

BOOT0

BOOT0

high, pull

NRST

NRST

low for 0.1 seconds, then bring it back high. This resets the slave and stops the program from running.

In

initBootloader

initBootloader

, I set up serial communication (8-bit data, even parity, 1 stop bit per AN2606) and send

0x7F

0x7F

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);
}

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);
}

If it's helpful, I can provide a picture of my board setup as well.

Troubleshooting Bootloader Access on Nucleo L476RG Using Nucleo L496ZG as Master

Troubleshooting Bootloader Access on Nucleo L476RG Using Nucleo L496ZG as Master

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