Driver Details

Silicon Labs Virtual COM Port Universal Driver

Date: 01/08/2021 Version:
WHQL Driver: Yes Provider: Silicon Laboratories Inc.

Supported operating system:

Windows 10 32-bit
Windows 10 64-bit

Release note:
Silicon Labs Virtual COM Port (VCP) Universal Driver for Windows 10

Package version: 10.1.10
Release date: 2021-01-13

This package contains a Virtual COM Port Universal driver for Microsoft
Windows 10 for use with Silicon Labs VCP USB Serial Bridges. These devices
include the CP2102N, CP2102, CP2103, CP2104, CP2105, CP2108, CP2109.

This package provides the CP210x VCP driver for the following versions
of Windows:

- Windows 10 (x64, x86)

VCP drivers of version 10.0.0 and later are released for Windows 10 as
Universal Drivers. This means they do not work on older version of Windows
such as Window 7 and 8.1. You should use this driver if you only need
support for Windows 10, or you need the Universal driver. If you require
support on older versions of Windows, you should use the legacy VCP driver
which can be found on the Silicon Labs web site. The legacy Windows VCP
drivers have version numbers less than 10.0.0.

The VCP driver package contains the following files and directories:
- silabser.inf -- Driver information file
- CP210xVCPInstaller_x64.exe -- 64-bit installer
- CP210xVCPInstaller_x86.exe -- 32-bit installer
- SLAB_License_Agreement_VCP_Windows.txt -- Software License
- CP210x_Universal_Windows_Driver_ReleaseNotes.txt -- this file

Additional files needed by installer
- dpinst.xml
- x64/silabser.sys
- x86/silabser.sys

The VCP driver is automatically installed by Windows Update for CP210x with
alternate PID values of 0xEA63, 0xEA7A, and 0xEA7B. These are not default

Otherwise, unzip the .zip file and you will have a directory containing the
driver installer files.

### Prompted install ###

If Windows prompts you to install a driver for a CP210x device
(for example, if you plug a CP210x into your computer):

1. Use the dialog to browse for the driver location
2. Locate the driver folder (that you previously unzipped)
3. Follow the instructions

### Manual install ###

1. Using Windows File Explorer, locate the driver folder
(that you previously unzipped)
2. Determine if you have 32-bit or 64-bit Windows
3. Double click to run the .exe file named CP210xVCPInstaller_xnn.exe
(where xnn is x64 for 64-bit and x86 is for 32-bit)
4. Follow the instructions

1. The device must be plugged in
2. Run Device Manager
3. Locate the device you want to uninstall
4. Right click on the device and choose "uninstall"
5. Follow the instructions

For technical support please visit the Silicon Labs support site:

RELEASE NOTES FOR 10.1.10 (2021-01-13)

Changes for VCP Driver
MCUSW-651 | Support baud rate up to 2187500 for CP2102, CP2104, CP2109
MCUSW-685 | Fixed the Blue Screen issue when running Windows Hardware Lab
| Kit for customized driver
MCUSW-783 | Microsoft Windows Certified (aka "WHQL Certified") for Windows
| 10 version 20H2 (2020-10-20)

RELEASE NOTES FOR 10.1.9 (2020-07-30)

Changes for VCP Driver
MCUSW-566 | Remove sanity/error checking on IOCTL_SERIAL_SET_BAUD_RATE for
| CP2103 devices.
MCUSW-596 | Microsoft Windows Certified (aka "WHQL Certified") for Windows
| 10 version 2004 (2020-05-27)
MCUSW-619 | Support for Directed PoFx (DFx - Directed Power Management
| Framework).

RELEASE NOTES FOR 10.1.8 (2019-06-24 (DriverVer = 06/20/2019,

Changes for VCP Driver
MCUSW-412 | Certified for Windows 10 RS6.
MCUSW-484 | WDFVERIFY() added to the driver. Configurable via Registry.
MCUSW-493 | Improved the tagging/tracking and parent-hierarchy of framework
| objects and framework object reference counts.
MCUSW-495 | Clear RTS on CloseHandle().
MCUSW-508 | IOCTL_SERIAL_GET_COMMSTATUS refactored to reduce USB-bus
| bandwidth, while still offering timely reporting.
MCUSW-518 | WDFVerifier parameter ForceLogsInMiniDump Registry parameter
| added for improved supportability.
MCUSW-519 | Resolve an SDV-identified issue: do not double-complete a
| Request on error paths.
MCUSW-526 | Creates the framework USB device object with client contract
| version USBD_CLIENT_CONTRACT_VERSION_602/0x602 (I.e. Register
| with "new" (to Windows 8) Windows USB driver stack).

RELEASE NOTES FOR 10.1.7 (2019-03-26 (DriverVer = 03/26/2019,

Changes for VCP Driver
MCUSW-473 | Fix length of nul-terminated legacy Dos Name string written to
MCUSW-483 | Fixed bug for Max Baud rate for CP2101, CP2104, CP2105 and
| CP2108 devices.

RELEASE NOTES FOR 10.1.6 (2019-03-19 (DriverVer = 03/15/2019,

Changes for VCP Driver
MCUSW-445 | Fix a blue-screen system crash bug with handling of ioctl
| IOCTL_SERIAL_WAIT_ON_MASK during power state changes.

RELEASE NOTES FOR 10.1.5 (2019-02-19 (DriverVer = 02/19/2019,

Changes for VCP Driver
MCUSW-414 | Implement an undocumented Registry-configured feature to ignore
MCUSW-417 | Read many of the Registry "parameter"-type settings first from
| the "parameters key" and then from the "hardware key", with the
| "hardware key" taking precedence (allows "driver wide, all
| devices" setting, but provides the capability to specify per-
| device settings (before we only supported per-device
| settings)).
MCUSW-439 | Fixed a bug whereby Close()-Open() on a CP2102N could get USB
| data toggle confused (I.e. issue USB CLEAR_FEATURE(HALT) to
| bulk endpoints to reset data toggle back to DATA0).
MCUSW-449 | Fix a Max Baud Rate bug (use device-specific MaxBauds (from the
| data-sheets): 3 Mbaud for CP2102N, 1 Mbaud for all other CP210x
| devices.).
MCUSW-450 | Fix Verification BSOD (race condition in the VCP device driver
| that can cause double completions): Only call
| DetachForCompletionUNcancelable on success of UNmark as
| cancelable in handling of IOCTL_SERIAL_WAIT_ON_MASK-related
| requests.

RELEASE NOTES FOR 10.1.4 (2018-12-07 (DriverVer = 11/26/2018,

Changes for VCP Driver
MCUSW-134 | Fixed an issue with handling of IOCTL_SERIAL_SET_WAIT_MASK,
| data arriving from the device into the driver. Previously, an
| indication of arriving data was made before making the data
| available, causing, in some conditions, subsequent requests for
| data after notification of data available to not deliver any
| data.
MCUSW-144 | Onecore-based editions of Windows 10 (I.e. Windows 10 IoT Core)
| do not, by design, create PortName entries in the Registry to
| specify the device's legacy DOS name (I.e. COM | Consequently, VCP enhanced to not treat this as a failing
| condition and to continue without creating legacy COM DOS
| devices.
MCUSW-148 | Rearchitected into two VCP driver packages:
| 1) Windows 7 and later Desktop Editions x86 and x64 driver
| package, and
| 2) Windows Universal (10 and later; Desktop, tablet, mobile,
| embedded) x86, x64, ARM, ARM64 driver package.
MCUSW-214 | Windows 10 Universal driver release (I.e. no Windows 7, 8 or
| 8.1 support)
MCUSW-352 | Workaround to issue where close during receipt of serial data
| caused CP2102N to hang.
MCUSW-369 | Certified for Windows 10 RS5.
MCUSW-393 | Fix bug due to some BaudRate-related math causing a divide-by-
| zero.
MCUSW-396 | Be defensive against the impossible case of getting a NULL
| object in the object completion routine.

RELEASE NOTES FOR 10.1.3 (2018-05-29)

Changes for VCP Driver
MCUSW-326 | Clear DTR on CloseHandle().

RELEASE NOTES FOR 10.1.2 (2018-05-14)

Changes for VCP Driver
MCUSW-134 | Fixed an issue with handling of IOCTL_SERIAL_SET_WAIT_MASK,
| data arriving from the device into the driver. Previously, an
| indication of arriving data was made before making the data
| available, causing, in some conditions, subsequent requests for
| data after notification of data available to not deliver any
| data.
MCUSW-211 | Windows 10 Universal driver release (I.e. no Windows 7, 8 or
| 8.1 support)
| "Voice MB v2.0" device.
MCUSW-315 | Certified for RS4/1803.

RELEASE NOTES FOR 10.1.1 (DriverVer=11/15/2017,

Changes for VCP Driver
MCUSW-134 | Fixed an issue with handling of IOCTL_SERIAL_SET_WAIT_MASK,
| and data arriving from the device into the driver. Previously,
| an indication of arriving data was made before making the data
| available, causing, in some conditions, subsequent requests
| for data after notification of data available to not deliver
| any data.

Everything below is the shared development history before creation of the
Windows 10 Universal driver. Everything above is development history of
the Universal driver.

RELEASE NOTES FOR 6.7.5 (2017-10-13)

Changes for VCP Driver
MCUSW-17 | IOCTL_SERIAL_GET_STATUS TransmittedCount fixed.
MCUSW-19 | CP210x_GET_CONFIG_DESCRIPTOR_IOCTL returned byte count fixed.
MCUSW-21 | Revert IOCTL_SERIAL_GET_COMMSTATUS behaviour to return cached
| information (reverse slowdown reported with v6.7.4 in some
| applications)
| Improve windbg logging, w.r.t. doing less when logging is not
| enabled (say, Release builds), or when particular subsystem is
| not enabled for logging.
MCUSW-110 | Windows 10 certified against RS2 (Creators Update).
MCUSW-207 | In a failed initialization, discard a reference to dynamically
| allocated memory once memory has been freed.
MCUSW-234 | timestamp SHA2 Signatures with SHA2 timestamps

RELEASE NOTES FOR (2017/01/30)

- Device Guard compliant
- CP210XFW-747: Add 3 new parallel PIDs one each for the single-, dual- &
quad-port CP210x devices (to be distributed via Windows Update)
- CP210XFW-741: Fix driver to use correct interface string index for the
multi-interface CP210x devices (CP2105 & CP2108). Return iProduct string
for other CP210x devices.
- CP210XFW-713: Add protection against IRP_MJ_CLOSE coming before
IRP_MJ_CLEANUP. In such case EvtFileCleanup callback was called with 0
FileObject, causeing a crash. Serenum is suspected of causing this, even
though there is no proof except that it's present, was introduced recently
and this crash was never registered before.
- CP210XFW-691: Fixed race between timer activation and request cancelation
during processing of read rwquests.
- Changed raw WDF read request timer to our wrapper.
- CP210XFW-693: bugfix: WMI command "wmic path Win32_SerialPort get
Availability^, DeviceID^, Name" is unable to enumerate the port.
- CP210XFW-686: EvtRequestCancel for wait mask IRP crashed because the
request was already completed. It didn't serialize well with other places
that can complete it. It looked like XOff IRP may have the same proble. This
patch is adding an extra check into *all* other EvtRequestCancel functions
to make sure this doesn't happen again.
- Changed IOCTLs returning polled-cached MDMSTS to explicitly read the
status. Use reg value DisableHwAccessInModemStatusIoctls to revert this
new functionality to old behavior.
- Improved debug prints.
- SerialDbgPrintEx used 1K of stack for the string, reduced to 256.
- Resolved many static Code Analysis warnings
- Added accounting for data in chip's TX queue. Added translation of
- CP210XFW-549, CP210XFW-536, CP210XFW-546: Generate events for
IOCTL_SERIAL_SET_WAIT_MASK from COMM_STATUS::ulErrors. Can be disabled by
DisableCommStatusPolling reg value.
- Added spinlock around ModemStatus change detection. Refactored modem
status event signalling to use common function.
- Move passive level functions into the paged section.
- MCUFW-740: Made device close operation wait for chip's Tx queue to empty.
Added registry settings DisableTxEmptyCheckInClose and
- Improve control transfer debug prints and clean up code, otherwise no
functional changes.
- MCUFW-740: Fixed EV_TXEMPTY to account for bytes in chip's Tx queue.
- MCUFW-740: New functions to sync access to comm error storage from
multiple threads.
- Added DisableTxEmptyCheckInGetCommStatusIoctl reg value.
- Refactor control request I/O. MCUFW-740: Fixed
- MCUFW-740: Made device close operation wait for chip's Tx queue to empty.
Added registry settings DisableTxEmptyCheckInClose and
- CP210XFW-648: Set a three second timeout on

RELEASE NOTES FOR 6.7.3 (2016/03/03)

- Down-rev the verison of KMDF the driver uses (CP210XFW-591. Use version of
KMDF natively included on Windows release)
- Bug fix of blue-screen system crash (CP210XFW-575. driver tries to clear a
Cancel Routine in a Request that doesn't have it.)

RELEASE NOTES FOR 6.7.2 (2015/11/23)

- Unified Windows 7, 8, 8.1 & 10 support (XP, Vista and Server 2003
available in version 6.7).
- ARM support added for Windows 10 and Windows 10 IoT Core.
- Silicon Labs-specific Serial Enumeration driver silabenm removed in favor
of the Windows "in-box" serenm.
- UpperFilter Serial Enumeration driver not enabled by default
- Updated to latest Microsoft build tools
- Resolved /W4 compilation warnings
- Resolved code analysis warnings
- Added a registry value ControlHandShakeForcedSetBits that can force
certain bits in the ControlHandShake variable to always be set.
- Add SAL-annotations to API header files.
- Bugfix an invalid memory access on device stop.
- Standardize branding Properties resources across all deliverables.
- Digitally sign all signable deliverables.
- Rewrote driver synchronization for data transmission paths.
- Resolve bugs arising from extended stress test.
- Added diagnostic variables to device extension.
- Bugfix a Write IRP stuck forever cauding bugcheck 9f-4 if call to USB
returns with error.
- Bugfix "packetized write" timeout may fail to act. And improved debug
- New reg value DisableS0Idle (default: 0) to replace EnablePowerManagewment
(default: 0 which actually ment "enable"). Also, DisableS0Idle=1 now
forces AllowIdleWhileOpen to 0.
- Driver ignores BreakOnEntry, DebugLevel and DebugFlag in registry.
- New CP2108 bug workarounds - GET_LINE_CTL byte swap and tx_empty().
- Fixed crash in read path.
- Simplified, commented and synchronized with NEWSTUFF EvtIoStop and
- Fixed memory leak on device removal when multiple devices are present.
- Bugfix Read IRP may never complete if other read IRPs are already waiting
when it arrives.
- Add CP2102N part numbers. Hnadle new part numbers in
- Resolve HCK INF warnings that became errors on HLK.
- Bugfix: Potential invalid memory access on device stop.
- Fixed possible memory overrun when writing CP2108 latch.
- Cumulative collection of improvements (due to code analysis, application
of latest toolset, etc.) and bug fixes.

RELEASE NOTES FOR 6.7.1 (2015/06/29)

- Added certification for Windows 10 Preview (Note: Windows 10 only;
use v6.7 for Windows prior to Windows 10)

RELEASE NOTES FOR 6.7 (2014/04/11)

- Added vendor-specific commands to the driver that do not affect normal
operation with standard CP210x devices.
- Modified write behavior to packetize data as a work around for a rare
USB 2.0 hub behavior seen only in Windows XP (x86).

RELEASE NOTES FOR 6.6.1 (2013/10/24)

- Added certification for Windows 8.1
- Added support for CP2108 devices
- Corrected bug where OS would hang on repetition of many rapid open/closes on
certain systems.


- Moving installer format to DPInst
- Supported under Windows 8
- Corrected bug in total write timeout calculation
- Corrected bug where EV_BREAK event could be misreported based on incoming
- Corrected another BSOD corner case regarding write cancellation


- Corrected BSOD corner case for a write cancellation
- Corrected memory leak that occurs when a device is plugged/unplugged
rapidly enough to allow driver startup function to fail


- Corrected BSOD corner case issue for handling control requests
- Corrected issue where USB 3.0 hubs would deliver data to the driver out
of order


- Corrected multiple BSOD issues by updating request handling for control
requests to the USB device, and the write completion method
- Corrected device removal routine to also undo the COM port naming in the
registry at removal time instead of when the device is closed after the


- Updated to 3.2 DriverInstaller to correct a bug seen when updating from an
old driver installer version


- Corrected a bug introduced in 6.2 which caused BSOD during surprise removal.
- Corrected a bug found in I/O cancellation corner case


- Corrected return value for DeviceIoControl() and other COM API functions
once the device is removed to properly show ERROR_ACCESS_DENIED (0x05)
instead of ERROR_BAD_COMMAND in GetLastError()
- Corrected bug in DTR/RTS reporting latency seen if you set DTR/RTS and ask
for it before the device has reported it to the host - now when it is
written it reads back immediately
- Corrected several USB requests that were improperly defined as device
requests when they are actually interface requests - this doesn't exhibit
and bugs in current single interface devices but was changed to be complete
and correct
- Added support for CP2104 and CP2105 devices


- Corrected a memory leak which could bog the system down after extended use
of a contiuously opened COM port, and conditionally yield bluescreens on
certain systems
- Corrected a problem where an IO reqest would sometimes return a busy
status to user mode, instead the queue is restarted if necessary before
adding an IO request to the queue
- Corrected a condition which would blue screen on cancelling write request
that hasn't been fully sent out USB
- Corrected the Capabilites return value, which incorrectly reported that
timeouts are not supported
- Corrected several Queue size return values, which affected behavior in the
MSCOMM control
- Corrected DTR/RTS value on device insertion, visible when Serial
Enumeration is disabled
- Corrected the ability to override Baud Rate and Line Control from the INF


- Corrected multiple blue screens and driver hangs related to race
conditions in the driver
- Corrected problem where driver hangs when 4 or more devices are connected
to a single transaction translator hub
- Corrected bugs that prohibited serial enumeration
- Corrected problem where IO requests were not completed/cancelled on a
- Corrected problem with dialing out or PPP connections
- Created IO queueing mechanism so that multiple reads, writes, etc. can be
queued and waited on

Supported Devices:
CP2101 USB to UART Bridge Controller
Silicon Labs CP210x USB to UART Bridge
Silicon Labs Dual CP2105 USB to UART Bridge
Silicon Labs Dual CP2105 USB to UART Bridge: Enhanced COM Port
Silicon Labs Dual CP2105 USB to UART Bridge: Standard COM Port
Silicon Labs Quad CP2108 USB to UART Bridge
Silicon Labs Quad CP2108 USB to UART Bridge: Interface 0
Silicon Labs Quad CP2108 USB to UART Bridge: Interface 1
Silicon Labs Quad CP2108 USB to UART Bridge: Interface 2
Silicon Labs Quad CP2108 USB to UART Bridge: Interface 3

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