HT82A520R HOLTEK [Holtek Semiconductor Inc], HT82A520R Datasheet - Page 44

• Manufacturer Part Number: HT82A520R
• Description: Full Speed USB 8-Bit OTP MCU with SPI
• Manufacturer: HOLTEK [Holtek Semiconductor Inc]

USB Interface
The device includes a USB interface function allowing for
the convenient design of USB peripheral products.
HT82A620R/HT82A520R Power Plane
There are three power planes for the device: USB SIE
VDD, VDDIO and the MCU VDD. For the USB SIE VDD
will supply all circuits related to the USB SIE and be
sourced from pin UBUS . Once the USB is removed from
the USB and there is no power in the USB BUS, the USB
SIE circuit is no longer operational.
For the PB port, it can be configured using a configuration
option to define the if the pins PB0~PB7 are supplied by
either the MCU VDD, or if pins PB0~PB6 are supplied by
the power pin VDDIO, in which case power will be sup-
plied on pin PB7. In the latter configuration, PB7 will be
configured as a power pin VDDIO and not a normal I/O
pin.
For the MCU VDD, it supplies all the HT82A520R/
HT82A620R circuit except the USB SIE which is supply by
UBUS.
USB Suspend Wake-Up Remote Wake-Up
If there is no signal on the USB bus for over 3ms, the de-
vice will enter a suspend mode. The Suspend flag, SUSP,
in the USC register, will then be set high and a USB inter-
rupt will be generated to indicate that the device should
jump to the suspend state to meet the requirements of the
USB suspend current spec. In order to meet the require-
ments of the suspend current, the firmware should disable
the USB clock by clearing the USBCKEN bit to zero.
The suspend current can be further decreased by setting
the SUSP2 bit in the UCC register. When the resume sig-
nal is sent out by the host, the device will be woken up the
by the USB interrupt and the Resume bit in the USC regis-
ter will be set. To ensure correct device operation, the pro-
gram must set the USBCKEN bit in the UCC register high
and clear the SUSP2 bit in the UCC register. The Resume
signal will be cleared before the Idle signal is sent out by
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the host and the Suspend line in the USC register will
change to zero. So when the MCU detects the Suspend
bit in the USC register, the condition of the Resume line
should be noted and taken into consideration.
The device has a remote wake up function which can
wake-up the USB Host by sending a wake-up pulse
through RMWK in the USC register. Once the USB Host
receives a wake-up signal from the device it will send a
Resume signal to the device.
USB Interface Operation
The device has 4 Endpoints, EP0~EP3. EP0 supports
Control transfer. All EP1~EP3 support Interrupt or Bulk
transfer.
All endpoints except EP0 can be configured as 8, 16, 32 or
64 FIFO size using the register UFC0 and UFC1. EP0 has
an 8-byte FIFO size. The Total FIFO size is 64+8 bytes.
The URD in the USC register is the USB reset signal con-
trol function definition bit.
HT82A520R/HT82A620R
October 23, 2009