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CHAPTER 6 USB CONTROLLER
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Preliminary User’s Manual S14767EJ1V0UM00
(b) Rx assemble mode
USB Controller sets EP2FO (EndPoint2 No Data) bit (Bit 9) in USB General Status Register2.
USB Controller writes dummy data to Data Buffer (In fact, USB Controller only increment pointer which addresses
Data Buffer by MaxPacketSize. No DMA transfer occurs.) so that the sum of received data and dummy data becomes
equal to MaxPacketSize.
After USB Controller receives “USB short packet”, USB Controller writes Rx Indications which indicates that EP2
FIFO Overrun has occurred.
(c) Rx separate mode
USB Controller sets EP2FO (EndPoint2 No Data) bit (Bit 9) in USB General Status Register2.
USB Controller writes dummy data to Data Buffer (In fact, USB Controller only increment pointer which addresses
Data Buffer by MaxPacketSieze. No DMA transfer occurs.) so that the sum of received data and dummy data
becomes equal to MaxPacketSize.
USB Controller writes Rx Indications which indicates that EP2 FIFO Overrun has occurred.
6.6.10 Rx indication
For every data segment that it receives, USB Controller writes a receive indication into the receive mailbox. After
writing a receive indication, USB Controller sets the receive completion bit of the USB General Status Register to 1
and, provided it is not masked, issues an interrupt.
The format of the receive indication is as shown below.
Figure 6-25. Receive Indication Format
31
15
0
16
Status
Size
Address
26
Reserved
25
EPN
30 29
Word1
Word2
28
Remark
Bit29 to Bit25 are reserved.
EPN:
Field that indicates the EndPoint number.
001:
EndPoint0
011:
EndPoint2
101:
EndPoint4
111:
EndPoint6
Status:
Field that indicates the status upon data receiving.
Bit25: When set to 0, indicates that an data corruption didn’t occur on EndPoint2.
When set to 1, indicates that an data corruption occurred on EndPoint2.
Bit24: When set to 0, indicates that an IBUS error has not occurred.
When set to 1, indicates that processing terminated abnormally due to the occurrence of an IBUS
error.
When this bit is set to 1, the Address field has no meaning.
Bit23: When set to 0, indicates that the received data is other than a USB Setup packet.
When set to 1, indicates that the received data is a USB Setup packet.