HT45B0K Holtek Semiconductor, HT45B0K Datasheet - Page 7

• Manufacturer Part Number: HT45B0K
• Description: SPI to USB Bridge
• Manufacturer: Holtek Semiconductor

HT45B0K
SPI to USB Bridge
USB Module
Note: “x” here stands for “don’t care”.
Rev 1.00
Command Type
USB Status and Control Registers
USB Accessing Commands
Read Registers
Write Registers
To communicate with an external USB host, the internal USB module has the external pins known
as UDP and UDN along with the 3.3V regulator output V33O. All data transmissions and receptions
between MCU and USB module including USB commands are conducted along the interconnected
SPI interface. The USB module has 6 endpoints and 160 bytes FIFO for the endpoints respectively.
A Serial Interface Engine (SIE) decodes the incoming USB data stream and transfers it to the
correct endpoint buffer memory (FIFO). The USB function control is implemented using a series
of registers accessed by the MCU using its SPI Master serial interface. A series of status registers
provide the user with the USB data transfer situation as well as any error conditions. The USB
contains its own independent interrupt which can be used to indicate when the USB FIFOs are
accessed by the host device or a change of the USB operating conditions including the USB
suspend mode, resume event or USB reset occurs.
There are several registers associated with the USB function. Some of the registers control the
overall function of the USB module as well as the interrupts, while some of the registers contain
the status bits which indicate the USB data transfer situations and error condition. Also there are
FIFOs for the USB endpoints to store the data received from or to be transmitted to the USB host.
The USB module has 6 endpoints (EP0~EP5) with different FIFO size for each one. The FIFO size
is 8 bytes for EP0~EP2 and EP4 which support “Interrupt transfer”, while the FIFO size for EP3
and EP5 is 64 bytes which can support “Bulk transfer”.
There are both read and write commands for accessing the USB Module. For reading and writing
to registers, both command and address information is contained within a single byte. A series of
registers which are addressed by 5 address bits A4~A0 are available to control the USB module for
Read/Write Registers commands. The format for reading and writing commands is shown in the
following table.
Bit 7
0
1
Bit 6
x
x
Bit 5
x
x
7
Bit 4
A4
A4
Bit 3
A3
A3
Bit 2
A2
A2
Bit 1
A1
A1
March 22, 2010
www.DataSheet4U.com
Bit 0
A0
A0