HT46RB50 Holtek Semiconductor, HT46RB50 Datasheet - Page 26

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

Suspend Wake-Up or Remote Wake-Up
If there is no signal on the signal bus for over 3ms, the
HT46RB50 will go into suspend mode. The Suspend
line (bit 0 of the USC) will be set to 1 and a USB interrupt
is triggered to indicate that the HT46RB50 should jump
to suspend state to meet the 500 A USB suspend cur-
rent spec.
In order to meet the 500 A suspend current, the firm-
ware should disable the USB clock by clearing the
USBCKEN (bit3 of the UCC) to 0 . The suspend cur-
rent is about 400 A.
The user can also further decrease the suspend current
to 250 A by setting the SUSP2 (bit4 of the UCC). But if
the SUSP2 is set, user should make sure not to enable
the LVR OPT option, otherwise, the HT46RB50 will be
reset.
When the resume signal is sent out by the host, the
HT46RB50 will wake-up the by USB interrupt and the
Resume line (bit 3 of the USC) is set. In order to make
the HT46RB50 work properly, the firmware must set the
USBCKEN (bit 3 of the UCC) to 1 and clear the SUSP2
(bit4 of the UCC). Since the Resume signal will be
cleared before the Idle signal is sent out by the host and
the Suspend line (bit 0 of the USC) is going to 0 . So
when the MCU is detecting the Suspend line (bit0 of
USC), the Resume line should be remembered and
taken into consideration.
After finishing the resume signal, the suspend line will
go inactive and a USB interrupt is triggered. The follow-
ing is the timing diagram:
Rev. 1.10
26
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 receive
the wake-up signal from the HT46RB50, it will send a
Resume signal to the device. The timing is as follow:
USB Interface
The HT46RB50 has 4 Endpoints (EP0~EP3). EP0~EP2
are support Interrupt transfer, EP3 is support Bulk trans-
fer.
There are 12 registers, including USC (20H), USR
(21H), UCC (22H), AWR (address+remote wake-up
23H), STALL (24H), SIES (25H), MISC (26H), SETIO
(27H), FIFO0 (28H), FIFO1 (29H), FIFO2 (2AH) and
FIFO3 (2BH) used for the USB function.
The FIFO size of each FIFO is 8 byte (FIFO0), 8 byte
(FIFO1), 8 byte (FIFO2) and 64 byte (FIFO3), and total
of 88 bytes.
URD (bit7 of the USC) is USB reset signal control func-
tion definition bit.
September 7, 2006
HT46RB50