HT82B40A datasheet(29/54 Pages) HOLTEK

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HT82B40R/HT82B40A

Rev. 1.70

November 5, 2014

Suspend Wake-Up and Remote Wake-Up

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

vice will go into a suspend mode. The Suspend line (bit

0 of the USC register) will be set to

²1² and a USB inter-

rupt is triggered to indicate that the devices 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 bit which is bit3 of the SCC register to

²0².

The suspend current is 400

mA.

The user can further decrease the suspend current to

250

mA by setting the SUSP2 bit which is bit4 of the SCC

disable.

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

vices will wake up the MCU with a USB interrupt and the

Resume line (bit 3 of the USC register) is set. In order to

make the device function properly, the firmware must

set the USBCKEN (bit 3 of the SCC register) to

²1² and

clear the SUSP2 (bit4 of the SCC register). Since the

Resume signal will be cleared before the Idle signal is

sent out by the host, the Suspend line (bit 0 of the USC

²0². So when the MCU is detecting

the Suspend line (bit0 of USC register), the Resume line

condition should be noted and taken into consideration.

After finishing the resume signal, the suspend line will

go inactive and a USB interrupt will be triggered. The fol-

lowing is the timing diagram.

As the device has a remote wake up function it can

wake-up the USB Host by sending a wake-up pulse

through RMWK (bit 1 of the USC register). Once the

USB Host receives a wake-up signal from the devices, it

will send a Resume signal to the device. The timing is as

follows:

To Configure as PS2 Device

The devices can also be configured as a USB interface

or PS2 interface device, by configuring SPS2 (bit 4 of

the USR register) and SUSB (bit 5 of the USR register).

If SPS2=1, and SUSB=0, the device will be configured

as a PS2 interface, pin USBPDN is configured as a PS2

Data pin and USBPDP is configured as a PS2 Clk pin.

The user can read or write to the PS2 Data or PS2 Clk

pin by accessing the corresponding bit PS2DAI (bit 4 of

the USC register), PS2CKI (bit 5 of the USC register),

PS2DAO (bit 6 of the USC register) and PS2CKO (bit 7

of the USC register) respectively.

The 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, then PS2DAO should set to

²1². Oth-

erwise it is always read as

²0².

If SPS2=0, and SUSB=1, the device is configured as a

USB interface. Both the USBPDN and USBPDP is

driven by the SIE of the HT82B40R/ HT82B40A . The

user can only write or read the USB data through the

corresponding FIFO. Both the SPS2 and

SUSB default

²0².

USB Interface

There are eleven registers used for the USB function.

The AWR register contains the 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

WKEN

Remote wake-up

enable/disable

7~1

AD6~AD0

USB device address

AWR (42H) Register

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 . 1

U S B C L K

M i n . 2 . 5 m s

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