MCP2221 datasheet(31/80 Pages) MICROCHIP

31 / 80 page

 2015 Microchip Technology Inc.

DS20005292B-page 31

MCP2221

TABLE 3-9:

RESPONSE STRUCTURE – READ USB SERIAL NUMBER DESCRIPTOR STRING

SUB-COMMAND

Byte Index

Value

Effect

0xB0 Read Flash Data – command code echo

0x00 Command completed successfully

(2)

The number of bytes + 2 in the provided USB Serial Number

Descriptor String.

The actual String starts at Byte Index 4

0x03 The value at this index must always be 0x03

4 + 2 x Unicode_char_number + 0(1)

Lower byte of the 16-bit Unicode character

4 + 2 x Unicode_char_number + 1(1)

Higher byte of the 16-bit Unicode character

(4 + 2 x Unicode_char_number + 2) - 63(1)

Don’t care.

Only if the USB string descriptor is less than 60-bytes long in

total.

Note 1:

“Unicode_char_number” value starts from 0 to a maximum of 30 (included).

The value at Byte Index 2 must be 2 + 2 x (number of Unicode characters in the string).

TABLE 3-10:

RESPONSE STRUCTURE – READ CHIP FACTORY SERIAL NUMBER

SUB-COMMAND(1)

Byte Index

Value

Effect

0xB0

Read Flash Data – command code echo

0x00

Command completed successfully

Structure length

3Don’t

care

4 - (4 + Structure length - 1)

Structure data – Factory Serial Number String

(4 + Structure length) - 63

Don’t

care

Note 1:

The Chip Serial Number is typically 8 bytes in length.

MCP2221 Datasheet(PDF) 31 Page - Microchip Technology

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