11/21

STV0676

External interfaces

2.4.1

EEPROM format and contents

The remaining space is available for the string blocks indexed at locations 8, 9 and 10.

2.4.2

Strings

The strings referred to above (locations 8-10), are the USB string descriptors referenced from the

device, configuration and interface descriptors. The value should be set to ’0’ if the string is not

implemented or to the offset in bytes of the start of the string block in the EEPROM.

The first byte of each string block is the number of the characters in the string. Subsequent bytes

are the actual string, which need not include a terminating null (

Table 8: EEPROM format and contents

location

contents

0

fixed number, must be 0x’ED

1

fixed number, must be 0x’15

2

reserved, must be 0x’00

3

max device power (=mA/2, e.g. 400mA enter 0x’C8)

4

VidLo, low byte of the vendor ID

5

VidHi, highbyte of the vendor ID

6

PidLo, low byte of the product ID

7

PidHi, highbyte of the product ID

8

manufacturer string offset, example below

9

product string offset, see below

10

interface 0 String offset

11

reserved, must be 0x’00

12

reserved, must be 0x’00

13

checksum

Table 9: EEPROM device string example

Location

Contents

8

Manufacturer string offset = 16

16

String length = 5

17

String text = ‘H’ (in ascii)

18

String text = ‘e’ (in ascii)

19

String text = ‘l’ (in ascii)

20

String text = ‘l’ (in ascii)

21

String text = ‘o’ (in ascii)