Datasheet
MCP2221
DS20005292A-page 36 2014 Microchip Technology Inc.
5 GP3 Power-up Settings
Bit 7-5: Don’t care
Bit 4: GPIO Output value When GP3 is set as an output GPIO, this value will be
present at the GP2 pin at Power-up/Reset.
Bit 3: GPIO Direction (Input/Out-
put). Works only when GP3 is set
for GPIO operation.
1 GPIO Input mode
0 GPIO Output mode
Bit 2-0: GP3 Designation 111-100 Don’t care
011 Alternate function 2 (DAC2)
010 Alternate function 1 (ADC3)
001 Dedicated function operation (LED I2C)
000 GPIO operation
6-63 Don’t care
TABLE 3-14: SUB-COMMAND STRUCTURE – WRITE USB MANUFACTURER DESCRIPTOR
STRING SUB-COMMAND
Byte Index Value Effect
0 0xB1 Write Flash Data – command code
1 0x02 Write USB Manufacturer Descriptor String – writes the USB Manu-
facturer String Descriptor used during the USB enumeration
2
(2)
Number of bytes + 2 in the provided USB Serial Number Descriptor
String
3 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.
Note 1: “Unicode_char_number” value starts from 0 to a maximum of 30 (included).
2: The value at Byte Index 2 must be 2 + 2 x (number of Unicode characters in the string).
TABLE 3-15: SUB-COMMAND STRUCTURE – WRITE USB PRODUCT DESCRIPTOR
STRING SUB-COMMAND
Byte Index Value Effect
0 0xB1 Write Flash Data – command code
1 0x03 Write USB Product Descriptor String – writes the USB Product
String Descriptor used during the USB enumeration
2
(2)
Number of bytes + 2 in the provided USB Serial Number Descriptor
String. The actual String starts at Byte Index 4.
3 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
Note 1: “Unicode_char_number” value starts from 0 to a maximum of 30 (included).
2: The value at Byte Index 2 must be 2 + 2 x (number of Unicode characters in the string).
TABLE 3-13: SUB-COMMAND STRUCTURE – WRITE GP SETTINGS SUB-COMMAND (CONTINUED)
Byte
Index
Function Description Value Effect