MCP2221 USB 2.0 to I2C/UART Protocol Converter with GPIO

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

 2014-2017 Microchip Technology Inc.

DS20005292C-page 1

MCP2221

Features

Universal Serial Bus (USB)

• Supports Full-Speed USB (12 Mb/s)
• Implements USB Protocol Composite Device:

- Communication Device Class (CDC) for

USB-to-UART Conversion

- Human Interface Device (HID) for I

C Device

Control and Configuration

• 128-Byte Buffer to Handle Data Throughput at

Any Supported UART Baud Rate:

- 64-Byte Transmit
- 64-Byte Receive

• Human Interface Device (HID) for Both

C Communication and Control:

64-Byte Buffer to Handle Data Throughput at

Any I

C Baud Rate

• Fully-Configurable VID and PID Assignments and

String Descriptors

• Bus-Powered or Self-Powered
• USB 2.0-Compliant: TID# 40001594

USB Driver and Software Support

• Enumerates as a Composite USB Device (CDC

and HID) Using Standard Drivers for Virtual Com
Port (VCP) on the Following Windows

Operating

Systems: XP

(SP3), Vista

, 7, 8 and 8.1

• Configuration Utility for Establishing a Custom

Boot-Up Configuration

• I

C/SMBus Terminal

• Windows DLL

CDC and Universal Asynchronous
Receiver/Transmitter (UART) Options

• Communications Device Class (CDC) for the

USB-to-UART Option

• Responds to SET LINE CODING Commands to

Dynamically Change Baud Rates

• Supports Baud Rates: 300-115200
• UART T

and R

Pins Only

• Serial Number Used During the CDC

Enumeration Can Be Enabled by Using the
Microchip-Provided Configuration Utility or by
Calling the Proper API from the Support Libraries
for this Device

C/SMBus

• The Device Runs as an I

C Master. The Data to

Write/Read on the I

C Bus is Conveyed by the

USB Interface

• I

C Master

- Up to 400 kHz Clock Rate
- Supports 7-Bit or 10-Bit Addressable

Devices; 10-Bit Addressable Devices are
Supported through the PC Host Library

- Supports Block Reads/Writes of up to 65,535

Bytes

• SMBus Master

- Supports All of the SMBus Transfers
- SMBus Functionality Is Achieved through a

Combination of Chip and Support Library
Processing

- Up to 400 kHz Clock Rate

General-Purpose Input/Output (GPIO) Pins

• Four General-Purpose Input/Output Pins
• All GP Pins Can Be Assigned to Other

Functionalities

Other Functionalities

• UART Activity LED Outputs (UT

and UR

)

• SSPND Output Pin
• USBCFG Output Pin (Indicates When the

Enumeration Has Completed)

• Three ADC Inputs
• One DAC with Two Possible Output Options
• Clock Reference Output: 12 MHz or Other

Configurable Values

• External Interrupt Edge Detection

Other

• Operating Voltage: 3.0 to 5.5V
• Electrostatic Discharge (ESD) Protection: > 4 kV

Human Body Model (HBM)

• Industrial (I) Operating Temperature: –40°C to

+85°C

• Automotive AEC-Q100 Qualified

USB 2.0 to I

C/UART Protocol Converter with GPIO

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

MCP2221

DS20005292C-page 2

 2014-2017 Microchip Technology Inc.

Package Types

Block Diagram

D-

D+

MCP2221

PDIP/SOIC/TSSOP

USB

RST

GP2

GP3

SDA

SCL

MCP2221

4 x 4 QFN*

GP2

GP3

SDA

SCL

USB

D-

D+

GP1

GP0

RST

GP1

GP0

* Includes Exposed Thermal Pad (EP); see

Table 1-1

USB HID

USB CDC

CONFIG

C Master

UART

BUS MATRIX

GPIO

ADC/DAC

USB

Bus

D/R

GP Pins

MUX

IOC

CLKR

Internal

Oscillator

USB Module &

Transceiver

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

 2014-2017 Microchip Technology Inc.

DS20005292C-page 3

MCP2221

1.0

FUNCTIONAL DESCRIPTION

The MCP2221 is a USB-to-UART serial converter that
enables USB connectivity in applications that have
UART and/or I

C interfaces. The device reduces

external components by integrating the USB
termination resistors and the oscillator needed for USB
operation.

The MCP2221 has four GP pins for miscellaneous
functionalities (including GPIO, USBCFG, SSPND,
Clock Output, ADC, DAC and interrupt detector).
See

Table 1-1

and

Section 1.7 “Pin Mux Module”

for

details about the pin functions.

TABLE 1-1:

PINOUT DESCRIPTION

Pin

Name

PDIP,

SOIC,

SSOP

QFN

Pin

Type

Standard Function

Alternate Functions

GP0

I/O General purpose I/O or alternate

function pin

SSPND (OUT)

LED_UR

(OUT)

Signals when the host has
entered Suspend mode
UART R

LED activity output

(factory default)

GP1

I/O General purpose I/O or alternate

function pin

CLKR (OUT)

ADC1 (IN)

LED_UT

(OUT)

IOC (IN)

Clock Reference Output

ADC Channel 1

UART T

Led activity output

(factory default)
External interrupt edge detector

RST

Reset input (with internal pull-up) N/A

UART R

pin (input)

N/A

UART T

pin (output)

N/A

GP2

I/O General purpose I/O or alternate

function pin

USBCFG (OUT)

ADC2 (IN)

DAC1 (OUT)

USB device configured status
(factory default)

ADC Channel 2

DAC Output 1

GP3

I/O General purpose I/O or alternate

function pin

LED_I2C (OUT)

ADC3 (IN)

DAC2 (OUT)

USB-I

C traffic indicator (factory

default)

ADC Channel 3

DAC Output 2

SDA

I/O I

C Data line

N/A

SCL

I/O I

C Clock line

N/A

USB

USB USB Power pin (internally

connected to 3.3V)
Should be locally bypassed with
a high-quality ceramic capacitor

D-

USB USB D-

D+

USB USB D+

Ground

—

14
15

—

Not Connected

Power

—

Exposed Thermal Pad (EP)
Do not electrically connect.

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

MCP2221

DS20005292C-page 4

 2014-2017 Microchip Technology Inc.

1.1

Supported Operating Systems

The following operating systems are supported:
• Windows

– XP (SP3), Vista, 7, 8 and 8.1

• Linux

– any distribution with support for CDC

and HID classes

• Mac OS

– all versions – beginning with 10.7

1.1.1

ENUMERATION

The MCP2221 enumerates as a composite USB device
after Power-on Reset (POR). The device enumerates
as both a Human Interface Device (HID) for I

C, GPIO

control, and as CDC for the USB-to-UART converter.

1.1.1.1

USB HID

The MCP2221 enumerates as an HID, so the device
can be configured, while the I

C and GPIO can be

controlled. A DLL package, with example applications
and tools, is supplied by Microchip on the device web
page on the Microchip web site,

www.microchip.com

1.1.1.2

USB CDC

The CDC enumeration implements the USB-to-UART
data translation.

1.2

Bus-Matrix Module

The Bus-Matrix module is the heart of the MCP2221.

All other modules are tied together and controlled via

the Bus-Matrix module. This module manages the data
transfers between the USB and the UART, the I

Master module, as well as the command requests
generated by the USB host controller and commands
for controlling the function of the UART, GPIO, ADC,
DAC and Clock Output.

1.2.1

UART

The control module interfaces to the UART and USB
modules.

1.2.2

ACCESSING THE DEVICE

The MCP2221 can be accessed for reading and writing
via USB host commands. The device cannot be
accessed or controlled via the UART interface.

1.3

UART Interface

The MCP2221 UART interface consists of the T

and

data signals.

The UART is configurable for several baud rates. The
available baud rates are listed in

Table 1-2

1.3.1

GET/SET LINE CODING

The GET_LINE_CODING and SET_LINE_CODING
commands are used to read and set the UART
parameters while in operation. For example, terminal
applications (e.g., Putty, RealTerm, Hyperterminal,
etc.) send the SET_LINE_COMMAND when connecting
to the port. The MCP2221 responds by setting the baud
rate only.
The other parameters (Data Bits, Parity, Stop Bits)
remain unchanged.

1.3.1.1

Rounding Errors

Primary baud rate settings (with associated rounding
errors) are shown in

Table 1-2

If baud rates other than the ones shown in the table are
used, the error percentage can be calculated using

Equation 1-1

to find the actual baud rate.

EQUATION 1-1:

SOLVING FOR ACTUAL
BAUD RATE

1.3.2

CUSTOM BAUD RATES

Custom baud rates are configured by sending the
SET_LINE_CODING USB command. See

Section 2.0

“USB Enumeration Process”

for more information.

Note:

MCP2221 supports only eight Data bits,
no Parity, and one Stop bit.

TABLE 1-2:

UART PRIMARY BAUD
RATES

Desired Rate

Actual rate

% Error

300

0.00%

1200

0.00%

2400

0.00%

4800

0.00%

9600

0.00%

19200

0.00%

38400

38339

0.16%

57600

57692

0.16%

115200

115385

0.16%

ActualRate

12MHz

int x

 

------------------

Where:

12MHz

DesiredBaud

-----------------------------------

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

 2014-2017 Microchip Technology Inc.

DS20005292C-page 5

MCP2221

1.4

Device Configuration

The MCP2221 keeps all the essential device
configuration settings stored in Flash memory.
Device configuration settings affect the way the
MCP2221 behaves at run time.
The settings are stored into the Flash memory on the
device. Some of the settings are also copied into
SRAM at Power-Up/Reset.
These device configuration settings reside in the
following two distinct areas of Flash memory:
• Chip Settings

The Chip Settings area stores the key MCP2221
parameters – USB parameters, ADC/DAC
reference voltage choice, start-up DAC value,
Clock Reference output (CLKR) frequency and
duty cycle values.

• GP Settings

The GP Settings area stores the GP designation
settings. For GP settings that are assigned to
GPIO output operation, output values (logic 1 or 0)
are also specified.

Even though the MCP2221 places a partial copy of the
Chip Settings in SRAM, the following Chip Settings
always reside in Flash:
• USB Manufacturer/Product and Serial Number

descriptors

• USB VID and PID pair
• USB options (e.g., the requested amount of

current that is presented to the USB host during
the USB enumeration process)

1.4.1

POWER-UP RESET DEVICE
CONFIGURATION BEHAVIOR

At Power-up Reset, the MCP2221 configures the

device options (GP designation, special function pins
parameters and USB enumeration options) according
to the Flash settings. Then, the Flash Chip Settings and
GP Settings are loaded into SRAM to allow for their
temporary modification at run time.
Chip Settings of the Device Configuration Flash are
copied partially into SRAM. Only the run-time-modifiable
parameters are copied into SRAM.
GP Settings of the Device Configuration Flash (GP
settings area) are copied entirely into the SRAM. By
copying the GP settings completely into SRAM, the
user is allowed to completely change the GP
designation at run time.
The SRAM copy of the settings can be altered at run
time in order to change certain device behavior, e.g.,
GP designation (the GPs can be re-assigned for a
different type of operation than the one assigned at
Power-up) and special parameters (DAC value,

ADC/DAC voltage references, Clock output value).

FIGURE 1-1:

CHIP SETTINGS RUN
TIME MANAGEMENT

The SRAM settings (GP and partial Chip Settings) can
be modified through USB HID commands and they will
have an effect on the following device features:
• GP pin designation (switch between GPIO,

dedicated or special functions modes)

• GPIO direction and output value (only for GPIO

outputs) – for the GPs assigned to work in GPIO
mode

• Clock Output duty cycle and value – if GP1 is

assigned for CLKR mode (Clock Reference
output mode), by modifying the SRAM settings,
the clock frequency and duty cycle can be
changed at run time

• DAC value and voltage reference used – the DAC

value setting as well as the voltage reference
used for it are stored in SRAM settings and they
can be changed at run time. Through this
mechanism, at run time the user can change the
DAC value, as well as the voltage reference.

• ADC voltage reference value – the voltage

reference used for ADC conversions can be
changed by altering its corresponding SRAM
setting

• Interrupt-on-change (IOC) detector settings – if

GP1 is assigned for IOC mode, the SRAM
settings are used for setting up the triggers used
for external interrupt detection (positive or
negative edge detection, or both)

Copy FLASH Chip and
GP settings to SRAM

USB enumeration

and configuration

complete

Change the

SRAM settings

Power-up Reset

changes needed

No Yes

SRAM settings

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

MCP2221

DS20005292C-page 6

 2014-2017 Microchip Technology Inc.

1.4.2

CHIP SETTINGS MAP

The Chip Settings area resides in Flash memory and is
copied into SRAM at run time. Not all of the device’s
settings can be altered at run time. All the fields in the
Flash settings can be altered by the user.

TABLE 1-3:

CHIP SETTINGS MAP

Byte

Index

Register Name

Comments

CHIPSETTING0

Controls the USB CDC serial number enumeration, default state for the GP LED
designation, default state for GP dedicated-function pins and chip settings
protection level

CHIPSETTING1

Default clock output divider and duty cycle

CHIPSETTING2

DAC reference options and default DAC value

CHIPSETTING3

ADC reference and interrupt detection settings

USBVIDL

USB VID lower byte

USBVIDH

USB VID higher byte

USBPIDL

USB PID lower value

USBPIDH

USB PID higher byte

USBPWRATTR

USB power attributes

USBREQCRT

USB required current

PASS0

Password byte 0

PASS1

Password byte 1

PASS2

Password byte 2

PASS3

Password byte 3

PASS4

Password byte 4

PASS5

Password byte 5

PASS6

Password byte 6

PASS7

Password byte 7

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

 2014-2017 Microchip Technology Inc.

DS20005292C-page 7

MCP2221

REGISTER 1-1:

CHIPSETTING0 REGISTER

R/W-0

R/W-1

R/W-0

CDCSNEN LEDURXINST LEDUTXINST LEDI2CINST SSPNDINST USBCFGINST CHIPPROT1 CHIPPROT0

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7

CDCSNEN: USB CDC Serial Number Enable
1 = USB CDC Serial Number is enumerated
0 = No USB CDC Serial Number enumeration (factory default)

bit 6

LEDURXINST: LED UART R

Inactive State

1 = LED UART R

is inactive high and active low (factory default)

0 = LED UART R

is inactive low and active high

bit 5

LEDUTXINST: LED UART T

Inactive State

1 = LED UART T

is inactive high and active low (factory default)

0 = LED UART T

is inactive low and active high

bit 4

LEDI2CINST: LED I

C Inactive State

1 = LED I

C is inactive high and active low (factory default)

0 = LED I

C is inactive low and active high

bit 3

SSPNDINST: SSPND Inactive State
1 = SSPND is inactive high and active low (factory default)
0 = SSPND is inactive low and active high

bit 2

USBCFGINST: USBCFG Inactive State
1 = USBCFG is inactive high and active low (factory default)
0 = USBCFG is inactive low and active high

bit 1-0

CHIPPROT<1:0>: Chip Settings Protection Level
11 =Reserved
10 =Permanently locked
01 =Password protection
00 =Chip settings unprotected (factory default)

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

MCP2221

DS20005292C-page 8

 2014-2017 Microchip Technology Inc.

REGISTER 1-2:

CHIPSETTING1 REGISTER

R/W-0

R/W-1

R/W-0

R/W-1

R/W-0

—

CLKDC1

CLKDC0

CLKDIV2

CLKDIV1

CLKDIV0

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-5

Reserved: Set to ‘0’

bit 4-3

CLKDC<1:0>: Clock-Out Duty Cycle
11 =Duty cycle 75% (75% of 1 clock period is logic ‘1’ and 25% of 1 clock period is logic ‘0’)
10 =Duty cycle 50% (50% of 1 clock period is logic ‘1’ and 50% of 1 clock period is logic ‘0’)

(factory default)

01 =Duty cycle 25% (25% of 1 clock period is logic ‘1’ and 75% of 1 clock period is logic ‘0’)
00 =Duty cycle 0% (100% of 1 clock period is logic ‘0’)

bit 2-0

CLKDIV<2:0>: Clock-Out Divider Output
111 =375 kHz clock output
110 =750 kHz clock output
101 =1.5 MHz clock output
100 =3 MHz clock output
011 =6 MHz clock output
010 =12 MHz clock output (factory default)
001 =24 MHz clock output
000 =Reserved

REGISTER 1-3:

CHIPSETTING2 REGISTER

R/W-1

R/W-0

R/W-1

R/W-0

DACVRM1

DACVRM0

DACREF

DACVAL4

DACVAL3

DACVAL2

DACVAL1

DACVAL0

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-6

DACVRM<1:0>: DAC Internal Voltage Reference (DAC VRM) Selection
11 =VRM voltage is 4.096V (only if V

is above this voltage)

10 =VRM voltage is 2.048V (factory default)
01 =VRM voltage is 1.024V
00 =VRM is off

bit 5

DACREF: DAC Reference Output Selection
1 = DAC reference output is DAC VRM voltage selection
0 = DAC reference output is V

(factory default)

bit 4-0

DACVAL<4:0>: Initial DAC Output Value
5-bit value for the DAC output (factory default is 8 decimal)

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

 2014-2017 Microchip Technology Inc.

DS20005292C-page 9

MCP2221

REGISTER 1-4:

CHIPSETTING3 REGISTER

R/W-0

R/W-1

R/W-0

R/W-1

R/W-0

—

INTDETFEEN INTDETREEN ADCVRM1

ADCVRM0

ADCREF

—

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7

Reserved: Set to ‘0’

bit 6

INTDETFEEN: Interrupt Falling Edge Detect Enable
1 = Interrupt detector will trigger when a falling edge is detected (factory default)
0 = Falling edges will not trigger the detector

bit 5

INTDETREEN: Interrupt Rising Edge Detect Enable
1 = Interrupt detector will trigger when a rising edge is detected (factory default)
0 =

Rising edges will not trigger the detector

bit 4-3

ADCVRM<1:0>: ADC Internal Voltage Reference (ADC VRM) Selection

11 =VRM voltage is 4.096V (only if V

is above this voltage)

10 =VRM voltage is 2.048V
01 =VRM voltage is 1.024V (factory default)
00 = VRM is off

bit 2

ADCREF: ADC Reference Output Selection

1 = ADC reference output is ADC VRM voltage selection (factory default)
0 =

ADC reference output is V

bit 1-0

Reserved: Set to ‘0’

REGISTER 1-5:

USBVIDL REGISTER

R/W-1

R/W-0

R/W-1

R/W-0

USBVIDL7

USBVIDL6

USBVIDL5

USBVIDL4

USBVIDL3

USBVIDL2

USBVIDL1

USBVIDL0

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-0

USBVIDL<7:0>: USB VID Lower Byte (factory default: 0xD8(hex))

REGISTER 1-6:

USBVIDH REGISTER

R/W-0

R/W-1

R/W-0

USBVIDH7

USBVIDH6

USBVIDH5

USBVIDH4

USBVIDH3

USBVIDH2

USBVIDH1

USBVIDH0

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-0

USBVIDH<7:0>: USB VID Higher Byte (factory default: 0x04(hex))

/var/www/html/datasheet/sites/default/files/pdfhtml_dummy/20005292C-html.html

MCP2221

DS20005292C-page 10

 2014-2017 Microchip Technology Inc.

REGISTER 1-7:

USBPIDL REGISTER

R/W-1

R/W-0

R/W-1

R/W-0

R/W-1

USBPIDL7

USBPIDL6

USBPIDL5

USBPIDL4

USBPIDL3

USBPIDL2

USBPIDL1

USBPIDL0

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-0

USBPIDL<7:0>: USB PID Lower Byte (factory default: 0xDD(hex))

REGISTER 1-8:

USBPIDH REGISTER

R/W-0

USBPIDH7

USBPIDH6

USBPIDH5

USBPIDH4

USBPIDH3

USBPIDH2

USBPIDH1

USBPIDH0

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7-0

USBPIDH<7:0>: USB PID Higher Byte (factory default: 0x00(hex))

REGISTER 1-9:

USBPWRATTR REGISTER

R/W-0

—

SELFPWR

REMWKUP

—

bit 7

bit 0

Legend:
R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

bit 7

Reserved: Reserved – set to ‘1’ (factory default)

bit 6

SELFPWR: USB Self-Powered Attribute
1 = Chip will enumerate on the USB bus as being self-powered
0 = Chip will enumerate on the USB bus as being USB-bus powered (factory default)

bit 5

REMWKUP: USB Remote Wake-Up Capability
1 = Chip will enumerate on the USB bus as being able to wake-up the USB host
0 = Chip will enumerate as not being capable of remote wake-up of the USB host (factory default)

bit 4-0

Reserved: Set all bits to ‘0’ (factory default)

Maker

Microchip Technology Inc.

Datasheet PDF Download

Data Sheet Datasheet