HT82K94E/HT82K94A

Rev. 2.40

19

November 5, 2014

Suspend Wake-Up and Remote Wake-Up

If there is no signal on the USB bus for over 3ms, the

HT82K94E/HT82K94A will go into suspend mode. The

Suspend line (bit 0 of the USC) will be set to

²1² and a

USB interrupt is triggered to indicate that the

HT82K94E/HT82K94A should jump to the suspend

state to meet the 500

mA USB suspend current spec.

In order to meet the 500

mA suspend current, the firm-

ware should disable the USB clock by clearing the

USBCKEN (bit3 of the SCC) to

²0². The suspend cur-

rent is 400

mA.

When the resume signal is sent out by the host, the

HT82K94E/HT82K94A will wake-up the MCUby USB in-

terrupt and the Resume line (bit 3 of the USC) is set. In

order to make the HT82K94E/HT82K94A function prop-

erly, the firmware must set the USBCKEN (bit 3 of the

SCC) to

²1². Since the Resume signal will be cleared

before the Idle signal is sent out by the host, the Sus-

pend line (bit 0 of the USC) will be set to

²0². So when

the MCU is detecting the Suspend line (bit0 of USC), the

Resume line should be remembered and taken into con-

sideration.

After finishing the resume signal, the suspend line will

go inactive and a USB interrupt is triggered. The follow-

ing is the timing diagram.

The device with remote wake-up function can wake-up the

USB Host by sending a wake-up pulse through RMWK (bit

1 of the USC). Once the USB Host receives a wake-up

signal from the HT82K94E/HT82K94A, it will send a Re-

sume signal to the device. The timing is as follows:

Configuring the Device as a PS2 Device

The HT82K94E/HT82K94A can be configured as a USB

interface or PS2 interface device, by configuring the

SPS2 (bit 4 of USR) and SUSB (bit 5 of the USR). If

SPS2=1, and SUSB=0, the HT82K94E/HT82K94A is

configured as a PS2 interface, pin USBD- is configured

as a PS2 Data pin and USBD+ is configured as a PS2 Clk

pin. User can easily read or write to the PS2 Data or PS2

Clk pin by accessing the corresponding bit PS2DAI (bit 4

of the USC), PS2CKI (bit 5 of the USC), PS2DAO (bit 6 of

the USC) and S2CKO (bit 7 of the USC) respectively.

User should make sure that in order to read the data

properly, the corresponding output bit must be set to

²1².

For example, if it is desired to read the PS2 Data by

reading PS2DAI, the PS2DAO should set to

²1². Other-

wise it is always read as

²0².

If SPS2=0, and SUSB=1, the HT82K94E/HT82K94A is

configured as a USB interface. Both the USBD- and

USBD+ is driven by the SIE of the HT82K94E/

HT82K94A. User can only write or read the USB data

through the corresponding FIFO.

Both SPS2 and SUSB default is

²0².

S U S P E N D

U S B R e s u m e S i g n a l

U S B _ I N T

S U S P E N D

U S B R e s u m e S i g n a l

U S B _ I N T

R M W K

M i n . 2 . 5 m s

M i n . 1 U S B C L K

USB Interface

There are eleven registers, including PIPE_CTRL (41H in bank 1), AWR (address + remote wake-up 42H in bank 1),

STALL (43H in bank 1), PIPE (44H in bank 1), SIES (45H in bank 1), MISC (46H in bank 1), Endpt_EN (47H in bank 1),

FIFO0 (48H in bank 1), FIFO1 (49H in bank 1), FIFO2 (4AH in bank 1) and FIFO3 (4BH in bank 1) used for the USB

function. AWR register contains current address and a remote wake up function control bit. The initial value of AWR is

²00H². The address value extracted from the USB command is not to be loaded into this register until the SETUP stage

is completed.

Bit No.

Label

R/W

Function

0

WKEN

W

Remote wake-up enable/disable

7~1

AD6~AD0

W

USB device address

AWR (42H) Register