ht82a836r Holtek Semiconductor Inc., ht82a836r Datasheet - Page 37

• Manufacturer Part Number: ht82a836r
• Description: Usb Audio Mcu
• Manufacturer: Holtek Semiconductor Inc.

USR Register
The USR register is the USB endpoint interrupt status
register and is used to indicate which endpoint is ac-
cessed and to select the USB bus. The endpoint request
flags, EP0F, EP1F, EP2F, EP3F and EP4F are used to
indicate which endpoints are accessed. If an endpoint is
accessed, the related endpoint request flag will be set to
interrupt is enabled and the stack is not full. When the
active endpoint request flag is serviced, the endpoint re-
quest flag has to be cleared to 0 by software.
Further explanation of each of the bits is given below:
UCC Register
The UCC register is the system clock control register
and is used to select the clock that is used in the MCU.
This register consists of a USB clock control bit,
USBCKEN, a second suspend mode control bit,
SUSP2, and a system clock selection bit, SYSCLK. The
register also controls the endpoint selection, which is
determined by bits EPS0, EPS1 and EPS2.
Rev. 1.00
1 and the USB interrupt will be generated if the USB
ESP0F~ESP4F
The ESP0F~ESP4F read/write bits are set by the SIE
an indicate whether the associated endpoint has been
accessed and a USB interrupt generated. After the in-
terrupt has been serviced the bits should be cleared
by the application program.
USB Control Register - USC
37
Further explanation of each of the bits is given below:
AWR Register
The AWR register is used to store the current USB de-
vice address and also for control of the Remote
Wake-up function. The initial value of the AWR register
is 00H . The address value extracted from the USB
command must not be loaded into this register until the
SETUP stage has finished.
EPS0~EPS2
These three read/write bits are for the endpoint FIFO
selection. It should be noted that Isochronous end-
points 2 and 3 are implemented in hardware, therefore
FIFO2 and FIFO3 cannot be read from or written to
using firmware.
USBCKEN
The USBCKEN read/write bit enables the USB clock.
SUSP2
The SUSP2 read/write bit is the second suspend bit
and is used to select a power reducing function when
the device is in the Suspend Mode. In the Normal
Mode this bit should be cleared to zero.
FSYS16MHz
This read/write bit is used to determine if the system
clock is derived from an external oscillator or from the
internal PLL 16MHz clock.
SYSCLK
The SYSCLK read/write bit is used to determine if the
system clock is either 6MHz or 12MHz.
HT82A836R
March 20, 2008