Bootloader command set

AN3262

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Doc ID 17845 Rev 2

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Bootloader command set

Table 1 lists commands supported by the OTA bootloader. A detailed command-by-

command protocol description follows.

Communication safety

All communications from the Host to the device are verified by:

●

Checksum: received blocks of data bytes are XORed. A byte containing the computed

XOR of all previous bytes is added to the end of each communication (checksum byte).

By XORing all received bytes, data + checksum, the result at the end of the packet

must be 0x00.

●

For each command, the host sends a byte and its complement (XOR = 0x00).

Each packet is either accepted (ACK) or discarded (NACK):

●

ACK = 0x79

●

NACK = 0x1F

Table 1.

OTA bootloader commands

Command

Command code

Command description

1.

This command is supported by unicast and broadcast packets, while all the other are unicast only.

0x00

Gets version number and list of commands allowed.

0x01

Gets bootloader version and Read Protection status of

the Flash memory.

0x02

Gets chip ID of device.

0x43

Erases memory pages of selected device.

0x31

Writes up to 96 bytes in memory of selected device.

2.

command set.

0x36

Writes up to 96 bytes in memory of selected device

incrementing next write address on device

automatically.

0x11

Reads up to 96 bytes of memory starting from a user-

specified address.

0x21

Starts the code at a given location for a given device.