HT42B564-x
USB (HID) to UART Bridge IC
Features
General Description
• Operating Voltage (VDD): 3.3V~5.5V
The HT42B564-x device is a high performance USB
to UART bridge controller with fully integrated
USB and UART interface functions, designed for
applications that communicate with various types
of UART. The device includes a USB 2.0 full
speed compatible interface which is used for PC
communication. The device also includes a fully
integrated high speed oscillator which is used as clock
source for the USB and UART baud rate generator.
The baud rate generator can support up to 115200bps
of baud rate for the UART interface.
• UART pin Voltage (VDDIO): 1.8V~VDD (Less than
VDD voltage)
• Power down and wake-up functions to reduce
power consumption
• Fully integrated 12MHz oscillator with 0.25%
accuracy for all USB modes which requires no
external components
• USB interface
♦♦ USB 2.0 Full Speed compatible
♦♦ Implements USB Human Interface Device (HID)
class
♦♦ Internal 1.5kΩ pull-high resistor on D+ pin
• Fully-duplex Universal Asynchronous Receiver and
Transmitter Interface – UART
♦♦ Supports Baud Rate up to 115200bps
♦♦ Supports maximum 32 bytes transmit buffer and 32
bytes receive buffer
♦♦ UART Data formats supported:
–– Data bits: 8
–– Stop bits: 1 and 2
–– Parity: odd, even, no parity
Supports RX pin resume signal to request a remote
wake-up
♦♦ Supports VDDIO pin for UART pins power supply
♦♦
• Supports standard Windows® drivers for Windows
XP, Vista, Win 7, Win 8/8.1, Win10
• Package types: 10-pin SOP
USB Bridge IC Naming Rules
HT42B 5 6 4 - x
Product Family
HT42B = Holtek Bridge IC
Version
Bridge Series of Host
5 = USB
1 = First Version
USB Class type
Bridge Series of Device
3 = CDC Class
6 = HID Class
Rev. 1.10
2 = I2C
3 = SPI
4 = UART
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HT42B564-x
Selection Table
Most features are common to all devices. The following table summarises the main features of each device.
Part No.
Description
VDD
USB
Virtual
HID
COM
2
FIFO/Buffer
Interface
Data Rate
I/O
VDD
Package
HT42B532-x
USB to I C
Bridge
√
—
TX: 62 bytes
RX: 62 bytes
Up to 400kHz
√
8SOP
10MSOP
HT42B533-x
USB to SPI
Bridge
√
—
TX: 128 bytes
RX: 128 bytes
Up to 8MHz
√
10MSOP
16NSOP
√
—
TX: 128 bytes
RX: 128 bytes
Up to 3Mbps
Baud
√
8/10SOP
10MSOP
16NSOP
—
√
TX: 32 bytes Up to 115.2kbps
RX: 32 bytes
Baud
√
10SOP
3.3V~
Full-Speed
USB to UART 5.5V
HT42B534-x
Bridge
HT42B564-x
USB (HID) to
UART Bridge
Block Diagram
HT42B564-x USB to UART Bridge
VDD
GND
3.3V
Regulator
Baud
Rate
Generator
Internal
Oscillator
VDDIO
Device
Power
V33O
D+
D-
USB
PHY
32B
TX
Buffer
USB
Controller
UART
32B
RX
Buffer
TX
RX
LED
UDET
External
MCU/
UART
circuitry
Pin Assignment
D+
1
10
VDD
2
9
V33O
TX
3
8
GND
RX
4
7
VDDIO
LED
5
6
UDET
D-
HT42B564-x
10 SOP-A
Package Type
Marking
10SOP
HT42B564-x
Note: x=1 for version number.
Rev. 1.10
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HT42B564-x
Pin Description
Pin Name
Type
Description
D+
I/O
USB D+ Line
D-
I/O
USB D- Line
TX
O
Asynchronous data output – UART Transmit
RX
I
Asynchronous data input – UART Receive
LED
O
TX/RX signal LED indication, active low
UDET
I
USB plug-in/out detect pin
O
3.3V regulator output
V33O
VDDIO
PWR
Positive power supply for TX/RX pins
VDD
PWR
Positive power supply, USB bus power
GND
PWR
Negative power supply, ground
Absolute Maximum Ratings
Supply Voltage . ..........................VSS-0.3V to VSS+6.0V
IOH Total . .......................................................... -80mA
Input Voltage ............................. VSS-0.3V to VDD+0.3V
IOL Total ...............................................................80mA
Storage Temperature ........................... -55°C to 150°C
Total Power Dissipation . .................................500mW
Operating Temperature ......................... -40°C to 85°C
Note: These are stress ratings only. Stresses exceeding the range specified under "Absolute Maximum Ratings"
may cause substantial damage to these devices. Functional operation of these devices at other conditions
beyond those listed in the specification is not implied and prolonged exposure to extreme conditions may
affect devices reliability.
D.C Characteristics
Ta=25°C
Symbol
Parameter
Test Conditions
VDD
Conditions
Min.
Typ.
Max.
Unit
V
VDD
Operating Voltage
—
—
3.3
—
5.5
VDDIO
UART Pins VDDIO input voltage
—
—
1.8
—
VDD
V
IDD
Operating Current
5V
No load, USB Plug-in
—
11
16
mA
ISUS
Suspend Current – USB
5V
Suspend mode, No load, USB
on, other peripherals off
—
360
450
μA
ISTB
Standby Current – Non-USB
3V
Standby mode, No load, USB
Plug-out, other peripherals off,
VDD power from VDDIO
—
0.1
1.0
μA
VIL
Input Pin Input Low Voltage
—
—
0
—
0.2VDDIO
V
VIH
Input Pin Input High Voltage
—
—
0.8VDDIO
—
VDDIO
V
4
8
—
mA
10
20
—
mA
-2
-4
—
mA
-5
-10
—
mA
IOL
I/O Pin Sink Current
IOH
I/O Pin Source Current
RPH
I/O Pin Pull-high Resistance
3V
5V
3V
5V
VOH = 0.9VDDIO
3V
—
20
60
100
kΩ
5V
—
10
30
50
kΩ
—
—
±1
μA
—
—
±1
μA
3.0
3.3
3.6
V
-5%
1.5
+5%
kΩ
3V
ILEAK
Input Leakage Current
VV33O
3.3V Regulator Output Voltage
5V
RUDP1
Pull-high Resistance between
D+ and V33O
3.3V
Rev. 1.10
VOL = 0.1VDDIO
5V
VIN = VDD or VIN = VSS
IV33O = 70mA
—
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HT42B564-x
A.C Characteristics
Ta=25°C
Symbol
fHIRC
Parameter
Test Condition
VDD
Condition
High Speed Internal RC Oscillator 3.3V~5.5V USB mode
tSST
System Start-up Timer Period
—
RX pin Wake-up from
power down mode
tRSTD
System Reset Delay Time
—
Power-on reset
Min.
Typ.
Max.
Unit
-0.25%
12
+0.25%
MHz
16
—
—
tHIRC
25
50
100
ms
Power-on Reset Characteristics
Ta=25°C
Symbol
Test Conditions
Parameter
VDD
Conditions
Min.
Typ.
Max.
Unit
VPOR
VDD Start Voltage to Ensure Power-on Reset
—
—
—
—
100
mV
RRPOR
VDD Rising Rate to Ensure Power-on Reset
—
—
0.035
—
—
V/ms
tPOR
Minimum Time for VDD Stays at VPOR to Ensure
Power-on Reset
—
—
1
—
—
ms
VDD
tPOR
RRPOR
VPOR
Rev. 1.10
4
Time
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HT42B564-x
USB Interface
The USB interface, being USB 2.0 full-speed
compatible, is a 4-wire serial bus that allows
communication between a host device and up to 127
max peripheral devices on the same bus. A token
based protocol method is used by the host device for
communication control. Other advantages of the USB
bus include live plugging and unplugging and dynamic
device configuration. As the complexity of USB data
protocol does not permit comprehensive USB operation
information to be provided in this datasheet, the reader
should therefore consult other external information for
a detailed understanding of the USB interface.
If there is no signal on the USB bus for over 3ms, the
USB device will enter the suspend mode. The device
enters the suspend state to meet the requirements of
the USB suspend current specification. When the
resume signal is asserted by the USB host, the device
will be woken up and leave the suspend mode.
Power Planes
USB VID and PID Configuration
There are two power planes for the device and they
are the USB bus power input (VDD) and 3.3V
regulator output (V33O).
The device has configured the default Vendor ID (VID:
0x04D9), Product ID (PID: 0xB564) and product
description strings of "USB HID UART Bridge".
For the USB SIE, VDD will supply all circuits related
to the USB SIE and be sourced from pin "VDD".
Once the USB device is removed from the USB bus
and there is no power on the USB BUS, the USB SIE
circuit will no longer be operational.
This device has been configured to the default USB
configuration data as shown in the following table.
As the USB device has a remote wake-up function,
the USB device can be woken-up the USB host by
sending a remote wake-up pulse. Once the USB host
receives a remote wake-up signal from the USB
device, the host will send a resume signal to the
device.
Parameter
USB Interface Operation
To communicate with an external USB host, the
internal USB module has external pins known as D+
and D- along with the 3.3V regulator output V33O.
A Serial Interface Engine, SIE, decodes the incoming
USB data stream and transfers it to the correct
endpoint buffer memory known as the FIFO. The
USB module has 3 endpoints, EP0 ~ EP2. Endpoint
0 supports the Control transfer while endpoint 1 ~
endpoint 2 support the Interrupt. The HT42B564-x
Bridge IC supports the USB Human Interface Device
Class, HID, for communication.
Endpoint
Control
1
Interrupt In
2
Interrupt Out
USB Vendor ID (VID)
0x04D9
USB Product ID (PID)
0xB564
Remote wake-up
Default enable
Manufacturer Name
Holtek
Product Description
USB HID UART Bridge
Serial Number
0000
USB Data Format
Read Data: 32 bytes FIFO for each read data, the first
byte valid for this number of data length received,
ranges from 0 to 31. If there are more than 31 bytes of
data, it will be divided into multiple times read.
Write Data: 32 bytes FIFO for each write data to
be written first byte number, ranging from 0 to 31.
If there are more than 31 bytes then write multiple
times.
Transfer Type
0
Value (hex)
USB Endpoint Transfer Type
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HT42B564-x
UART Interface
For data transfer, the UART function utilises a nonreturn-to-zero, more commonly known as NRZ,
format. This is composed of one start bit, eight data
bits and one or two stop bits. Parity is supported by
the UART hardware and can be setup to be even, odd
or no parity. For the most common data format, 8 data
bits along with no parity and one stop bit, denoted as 8,
N, 1, is used as the default setting, which is the setting
at power-on.
The HT42B564-x contains an integrated full-duplex
asynchronous serial communications UART interface
that enables communication with external devices
that contain a serial interface. The UART function
has many features and can transmit and receive data
serially by transferring a frame of data with eight data
bits per transmission as well as being able to detect
errors when the data is overwritten or incorrectly
framed. The UART function possesses its own
internal interrupt which can be used to indicate when
a reception occurs or when a transmission terminates.
The following diagram shows the transmit and receive
waveforms for 8-bit data format.
The integrated UART function contains the following
features:
Baud Rate Generator
• One or two stop bits
To setup the speed of the serial data communication,
the UART function contains its own dedicated
baud rate generator. The default UART baud rate is
9600bps and it can be controlled by the application
program.
• Baud rate generator with prescaler
The baud rate and miss rate table:
• Full-duplex, asynchronous communication
• 8 bits character length
• Even, odd or no parity options
• 32-byte Deep FIFO Transmit Data Buffer
• 32-byte Deep FIFO Receive Data Buffer
Baud Rate
Real Rate
Miss Rate (%)
• RX pin wake-up function
9600
9603.841537
0.04
19200
19207.68307
0.04
• UART pins power supply by VDDIO pin
38400
38461.53846
0.16
57600
57692.30769
0.16
115200
115384.6154
0.16
UART External Pins
To communicate with an external serial interface,
the internal UART has two external pins known as
TX and RX. The TX and RX pins are the UART
transmitter and receiver pins respectively.
UART Power Down and Wake-up
If the USB host sends a suspend signal to the
HT42B564-x USB device, it will enter the suspend
mode. It is recommended to ensure that the UART
data transmission or reception has finished before the
device enters the suspend mode.
UART Data Transfer Scheme
The data will be transferred to the Transmit Shift
Register from where it will be shifted out, LSB first,
onto the TX pin at a rate controlled by the Baud
Rate Generator. Data to be received by the UART
is accepted on the external RX pin, from where it is
shifted in, LSB first, to the Receiver Shift Register
at a rate controlled by the Baud Rate Generator.
The UART interface provides a 32 byte deep FIFO
transmit data buffer and a 32 byte deep FIFO receive
data buffer for applications.
Start
Bit
The UART function contains a receiver RX pin wakeup function. A falling edge on the RX pin will wake
up the device from the suspend mode.
Parity Bit
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Stop
Bit
Next
Start
Bit
8-bit Data Format
Rev. 1.10
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HT42B564-x
USB HID Protocol
USB VID/PID
VID: 0x04D9
PID: 0xB564
USB TO UART Command
The application program uses USB HID set/get feature command to implement UART settings. There are
following command:
• Get UARTSetting Command
• Set UARTSetting Command (CMDCode=01)
Get UARTSetting Command
Request Name
Report Type
Raw Data
Get_Report
Feature
D0~D7
D1~D8: UARTSettings (Refer to Table)
Byte
D0
Field
Size
CMDCode
Description
1
Command code.
D1~D4
DTERate
4
Data terminal rate,in bits per second.
(support 9600/19200/38400/57600/115200)
9600 → 80 25 00 00
19200 → 00 4B 00 00
38400 → 00 96 00 00
57600 → 00 E1 00 00
115200 → 00 C2 01 00
D5
CharFromat
1
Stop bits
0-1 Stop bits
1-2 Stop bits
D6
ParityType
1
Parity
0-None
1-Odd
2-Even
D7
DataBits
1
Data bits(only 8)
UARTSettings
Write Data
Set UARTSetting Command
Request Name
Report Type
Raw Data
Set_Report
Feature
D0~D7
D0~D7: UARTSettings (Refer to Table.1)
Request Name
Report Type
Raw Data
Interrupt
Output
D0~D31
Endpoint size 32bytes
CMDCode=01H
The first data of D0 is the data length.
Read Data
Request Name
Report Type
Raw Data
Interrupt
Input
D0~D31
Endpoint size 32bytes
The first data of D0 is the data length.
Rev. 1.10
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HT42B564-x
DLL Function
HT42B564-x USB Bridge DLL Function
Get the addresses
(FARPROC&) OpenFirstHIDDevice=GetProcAddress
(m_hLib,"OpenFirstHIDDevice");
(FARPROC&) OpenNextHIDDevice=GetProcAddress
(m_hLib,"OpenNextHIDDevice");
(FARPROC&) CloseHIDDevice=GetProcAddress
(m_hLib,"CloseHIDDevice");
(FARPROC&) SetFeature=GetProcAddress
(m_hLib,"SetFeature");
(FARPROC&) GetFeature=GetProcAddress
(m_hLib,"GetFeature");
Holtek provides a Dynamic-Link Library (DLL) to
setup the HT42B564-x Bridge IC for USB to UART
data communication.
The Dynamic-link library DLL is a shared library
of function executable files, available in different
languages for application calls to use. The complex
computing and communications USB is collated into
a "HIDAPI.DLL". Users can use this DLL to develop
different client applications without having to spend
excessive amounts of time to study and write USB
related functions.
Function Description:
HANDLE OpenFirstHIDDevice(DWORD wVID,
DWORD wPID, DWORD wUsagePage, DWORD
wUsage, BOOL bSync);
DLL Function Definition:
BOOL SetFeature(HANDLE hDevice, LPVOID
pData, DWORD nLen);
HANDLE OpenNextHIDDevice(DWORD wVID,
DWORD wPID, DWORD wUsagePage, DWORD
wUsage,BOOL bSync);
BOOL GetFeature(HANDLE hDevice, LPVOID
pData, DWORD nLen);
HANDLE OpenFirstHIDDevice(DWORD dwVID,
DWORD dwPID, DWORD dwUsagePage, DWORD
dwUsage, BOOL bSync);
Parameters:
HANDLE OpenNextHIDDevice(DWORD dwVID,
DWORD dwPID, DWORD dwUsagePage, DWORD
dwUsage, BOOL bSync);
void CloseHIDDevice(HANDLE hDevice);
wVID
Device Vendor ID. Any VID input will be
regarded as the Holtek Vendor ID 0x04D9
by default in this version. Consult with
Holtek if another VID is required.
wPID
Device Product ID. wUsagePage/wUsage
The UsagePage/Usage adopted by the
Report Descriptor will be written with a
value of "0" if it is not specified. More
detailed information is contained in the HID
spec. When the same VID/PID has multiple
interfaces simultaneously, it is required
to specify the exact UsagePage/Usage,
otherwise only the first interface handle
value will be returned.
Usage – Taking C language as an example:
• HINSTANCE hLib=LoadLibrary ("HIDAPI.DLL");
• The GetProcAddress function fetches the addresses
for accessing various functions
Taking C language as an example, the declarations
are as follows:
BOOL (*SetFeature)(HANDLE hDevice, LPVOID
pData, DWORD nLen);
BOOL (*GetFeature)(HANDLE hDevice, LPVOID
pData, DWORD nLen);
HANDLE (*OpenFirstHIDDevice)(DWORD
wVID, DWORD wPID, DWORD wUsagePage,
DWORD wUsage, BOOL bSync);
HANDLE (*OpenNextHIDDevice)(DWORD
wVID, DWORD wPID, DWORD wUsagePage,
DWORD wUsage, BOOL bSync);
void (*CloseHIDDevice)(HANDLE hDevice);
bSync
Use synchronous or asynchronous transmission.
Synchronous transmission means that the
function will not return a value until the
Input/Output has finished.
Return Value:
Represents the value of the activated device. A NULL
will be returned if the open operation has failed.
When the same VID/PID USB devices exist simultaneously,
the OpenFirstHIDDevice function can be used to open the
first one followed by an OpenNextHIDDevice function to
open the next one until a NULL is returned.
After activation, the device is able to execute ReadFile/
WriteFile operations, which are the Windows API
Standard Functions.
Rev. 1.10
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HT42B564-x
Void CloseHIDDevice(HANDLE hDevice);
Considerations:
Parameters:
• The OpenFirstHIDDevice/OpenNextHIDDevice
functions start up devices with a readable and
writeable permission, therefore the device specified
by the VID/PID should also be readable and
writable. This means that the Firmware must
provide OutputReport/InputReport or Interrupt IN/
Interrupt OUT.
hDevice Represents the value of the device to be
closed.
BOOL SetFeature(HANDLE hDevice, LPVOID pData,
DWORD nLen)
Parameters:
• Use general file access functions, such as
WriteFile(hDevice, …) in the C language to write
data to OutputReport or Interrupt OUT. The
required data length should be the Firmwaredefined OutputReport length with the addition
of one Report ID byte. The first byte must be the
Report ID. It will be "0" if there is no Report ID.
hDevice Represents the value of the activated device
pData
Data buffer where the Feature data is to
be written. The first byte should be Report
ID. A "0" value will be written to this byte
if there is no Report ID.
nLen
Length of the Feature data to be written.
The required length should be the Firmwaredefined Feature Report length with the
addition of one Report ID byte.
• Use general file access functions, such as
ReadFile(hDevice, …) in the C language, to read
data from InputReport or Interrupt IN. The required
data length should be the Firmware-defined
InputReport length with the addition of one Report
ID byte. The first byte must be the Report ID. It
will be "0" if there is no Report ID.
Return value:
1: Write success
0: Write fail
• To use the SetFeature/GetFeature functions, the
device must provide Feature Report, which means
the Report Descriptor of the Firmware should
contain the Feature Type.
BOOL GetFeature(HANDLE hDevice, LPVOID pData,
DWORD nLen);
Return value:
hDevice Represents the value of the activated device
pData
Data buffer where the Feature data is to
be read. The first byte should be Report
ID. A "0" value will be written to this byte
if there is no Report ID.
nLen
Length of the Feature data to be read.
The required length should be the
Firmware-defined Feature Report length
with the addition of one Report ID byte.
Return value:
1: Read success
0: Read fail
Rev. 1.10
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HT42B564-x
Application Circuits
VCC
VDD
1N5817
3.3V
5V or 3.3V
BAT
3.3V
VDDIO
VDD
0.1µF
USB
Connector
VBUS
DD+
VSS
10µF
0.1µF
0.1µF
GND
UDET
33Ω
33Ω
TX
RX
DD+
47pF
47pF
V33O
UART
RX
TX
MCU
Application
Circuit
LED
1µF
LED
330Ω
VDD
HT42B564-x
10 SOP-A
Note: 1. The VCC voltage must be less than the VDD voltage. The VCC supply can be sourced from a Li-battery.
2. The UDET pin can used to detect a USB plug-in for data transfer or to detect a USB plug-out for entering
the energy saving mode.
Rev. 1.10
10
December 27, 2017
HT42B564-x
Package Information
Note that the package information provided here is for consultation purposes only. As this information may be
updated at regular intervals users are reminded to consult the Holtek website for the latest version of the Package/
Carton Information.
Additional supplementary information with regard to packaging is listed below. Click on the relevant section to be
transferred to the relevant website page.
• Further Package Information (include Outline Dimensions, Product Tape and Reel Specifications)
• Packing Meterials Information
• Carton information
Rev. 1.10
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HT42B564-x
10-pin SOP (150mil) Outline Dimensions
Symbol
Dimensions in inch
Min.
Nom.
Max.
A
—
0.236 BSC
—
B
—
0.154 BSC
—
0.018
C
0.012
—
C’
—
0.193 BSC
—
D
—
—
0.069
E
—
0.039 BSC
—
F
0.004
—
0.010
G
0.016
—
0.050
H
0.004
—
0.010
α
0°
—
8°
Symbol
Rev. 1.10
Dimensions in mm
Min.
Nom.
Max.
A
—
6.00 BSC
—
B
—
3.90 BSC
—
C
0.30
—
0.45
C’
—
4.90 BSC
—
D
—
—
1.75
E
—
1.00 BSC
—
F
0.10
—
0.25
G
0.40
—
1.27
H
0.10
—
0.25
α
0°
—
8°
12
December 27, 2017
HT42B564-x
Copyright© 2016 by HOLTEK SEMICONDUCTOR INC.
The information appearing in this Data Sheet is believed to be accurate at the time
of publication. However, Holtek assumes no responsibility arising from the use of
the specifications described. The applications mentioned herein are used solely
for the purpose of illustration and Holtek makes no warranty or representation that
such applications will be suitable without further modification, nor recommends
the use of its products for application that may present a risk to human life due to
malfunction or otherwise. Holtek's products are not authorized for use as critical
components in life support devices or systems. Holtek reserves the right to alter
its products without prior notification. For the most up-to-date information, please
visit our web site at http://www.holtek.com.tw/en/home.
Rev. 1.10
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