ht82k94e Holtek Semiconductor Inc., ht82k94e Datasheet - Page 22

• Manufacturer Part Number: ht82k94e
• Description: Ht82k94e/ht82k94a -- Usb Multimedia Keyboard Encoder 8-bit Mcu
• Manufacturer: Holtek Semiconductor Inc.

USB Endpoint Interrupt Status Register
The register is used to indicate which endpoint is accessed or has external interrupt PA4/EXT is activated and to select
the serial bus (PS2 or USB). The endpoint request flags (EP0IF, EP1IF, EP2IF, EP3IF and EXTIF) are used to indicate
which endpoints are accessed. If an endpoint is accessed, the related endpoint request flag will be set to 1 and the
USB interrupt will occur (if the USB interrupt is enabled and the stack is not full). When the active endpoint request flag
is served, the endpoint request flag has to be cleared to 0 .
Where USB_flag bit is only a bit for firmware to store the USB-mode data. This bit only clear to zero after power-on reset.
System Clock Control Register
This register is designed to control the system clock and make the device to meet USB 500 A suspend current spec. as
well as a LVD indicator.
Since the device can operate at 6MHz or 12MHz in USB mode, so in order to make SIE work properly, there should has
a SYSCLK bit to indicate what system frequency is working.
The USBCKEN bit is used to turn-off or turn-on the SIE system clock to meet the USB 500 A suspend current. For
normal operation, this bit must be 1. Otherwise, the SIE cannot detect the USB signal.
PS2_flag bit is only a bit for firmware to store the PS2 mode data. This bit only clear to zero by hardware after power-on
reset. SUSPEND2 bit is used to second suspend mode.
Rev. 1.90
Bit No.
0
1
2
3
4
5
6
7
USB_flag
EP0IF
EP1IF
EP2IF
EP3IF
Label
SUSB
SPS2
R/W
R/W
R/W
R/W
R/W
R/W The PS2 function is selected when this bit is set to 1 . (Default= 0 )
R/W The USB function is selected when this bit is set to 1 . (Default= 0 )
R/W
When this bit is set to 1 (set by the SIE), it indicates the endpoint 0 is accessed and
a USB interrupt will occur. When the interrupt has been served, this bit should be
cleared by firmware.
When this bit is set to 1 (set by the SIE), it indicates the endpoint 1 is accessed and
a USB interrupt will occur. When the interrupt has been served, this bit should be
cleared by firmware.
When this bit is set to 1 (set by the SIE), it indicates the endpoint 2 is accessed and
a USB interrupt will occur. When the interrupt has been served, this bit should be
cleared by firmware.
When set to 1 , indicated endpoint 3 interrupt event . Must wait MCU to process in-
terrupt event, then clear this bit by firmware. This bit must be 0, then next interrupt
event will be process. Default value is 0.
Undefined, should be cleared to 0
This flag is used to show the MCU is in USB mode. (Bit=1)
This bit is R/W by FW and will be cleared to 0 after power-on reset. (Default= 0 )
USR (1DH) Register
22
Function
HT82K94E/HT82K94A
April 29, 2008