HT46RB50 Holtek Semiconductor, HT46RB50 Datasheet - Page 28

• Manufacturer Part Number: HT46RB50
• Description: A/D Type USB 8-Bit MCU
• Manufacturer: Holtek Semiconductor

There is a system clock control register implemented to select the clock used in the MCU. This register consists of USB
clock control bit (USBCKEN), second suspend mode control bit (SUSP2) and system clock selection (SYSCLK)
The following table defines which endpoint FIFO is selected, EPS2, EPS1 and EPS0.
The AWR register contains the current address and the remote wake-up function control bit. The initial value of the
AWR is 00H . The address value extracted from the USB command is not to be loaded into this register until the
SETUP stage is finished.
The STALL register shows whether the corresponding endpoint works properly or not. As soon as the endpoint works
improperly, the related bit in the STALL has to be set to 1 . The STALL will be cleared by the USB reset signal.
Rev. 1.10
Bit No.
Bit No.
Bit No.
0~2
7~1
3~0
7~4
3
4
5
6
7
0
EPS0~EPS2
STL3~STL0
USBCKEN
AD6~AD0
SYSCLK
(24MHz)
SUSP2
WKEN
Label
Label
Label
f
SYS
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Accessing endpoint FIFO selection.
EPS2, EPS1, EPS0:
000: Select endpoint 0 FIFO
001: Select endpoint 1 FIFO
010: Select endpoint 2 FIFO
011: Select endpoint 3 FIFO
100: Reserved for future expansion, cannot be used
101: Reserved for future expansion, cannot be used
110: Reserved for future expansion, cannot be used
111: Reserved for future expansion, cannot be used
If the selected endpoints do not exist, the related functions are not available.
USB clock control bit. When this bit is set to 1 , it indicates that the USB clock
is enabled.
Otherwise, the USB clock is turned-off.
This bit is used to reduce power consumption in suspend mode.
In normal mode, clear this bit to 0 (default)
In HALT mode, set this bit to 1 to reduce power consumption.
This bit is used to define the MCU system clock to come from either the exter-
nal OSC or from PLL output 24MHz clock.
0: system clock comes from OSC
1: system clock comes from PLL output 24MHz
This bit is used to specify the system clock oscillator frequency used by the
MCU. If a 6MHz crystal oscillator or resonator is used, this bit should be set to
to 0 (default).
Undefined, read as 0
Remote wake-up enable/disable
USB device address
Set by users when the related USB endpoints are stalled. They are cleared by
USB reset and Setup Token event
Undefined bit, read as 0
1 . If a 12MHz crystal oscillator or resonator is used. this bit should be cleared
STALL (24H) Definitions
AWR (23H) Definitions
UCC (22H) Definitions
28
Function
Function
Function
September 7, 2006
HT46RB50