Datasheet

 2014 Microchip Technology Inc. DS20005292A-page 33
MCP2221
TABLE 3-12: SUB-COMMAND STRUCTURE – WRITE CHIP SETTINGS SUB-COMMAND
Byte
Index
Function Description Value Effect
0 0xB1 Write Flash Data – command code.
1 0x00 Write Chip Settings – it will write the MCP2221 NVRAM device
settings.
2 Bit 7: CDC Serial Number
Enumeration Enable.
1 The USB serial number will be used during the USB enumeration
of the CDC interface.
0 No serial number descriptor will be presented during the USB
enumeration.
Bit 6: Initial value for
LEDUARTRX pin option
This value represents the logic level signaled when no UART RX
activity takes places. When the UART RX (of the MCP2221) is
receiving data, the LEDUARTRX pin will take the negated value
of this bit.
Bit 5: Initial value for
LEDUARTTX pin option
This value represents the logic level signaled when no UART TX
transmission takes place. When the UART TX (of the MCP2221)
is sending data, the LEDUARTTX pin will take the negated value
of this bit.
Bit 4: Initial value for LEDI2C pin
option
This value represents the logic level signaled when no I
2
C traffic
occurs. When I
2
C traffic is active, the LEDI2C pin (if enabled) will
take the negated value of this bit.
Bit 3: Initial value for SSPND pin
option
This value represents the logic level signaled when the device is
not in Suspend mode. Upon entering Suspend mode, the
SSPND pin (if enabled) will take the negated value of this bit.
Bit 2: Initial value for USBCFG
pin option
This value represents the logic level signaled when the device is
not USB configured. When the device will be USB configured,
the USBCFG pin (if enabled) will take the negated value of this
bit.
Bit 1-0: Chip Configuration Secu-
rity Option
11-10 Permanently locked
01 Password protected
00 Unsecured
3Bit 7-5 Don’t
care
Bit 4-0: Clock Output divider
value
If the GP pin (exposing the clock output) is enabled for clock out-
put operation, the divider value will be used on the 48 MHz USB
internal clock and its divided output will be sent to this pin.
4 Bit 7-6: DAC Reference voltage
option
11 Reference voltage is 4.096V (only if V
DD is above this voltage).
10 Reference voltage is 2.048V
01 Reference voltage is 1.024V.
00 Reference voltage is off (this is useful for the case in which the
DAC uses other reference than VRM DAC, i.e., VDD).
Bit 5: DAC reference option 1 DAC reference is VDD.
0 DAC reference is VRM DAC voltage.
Bit 4-0: Power-up DAC value