Cypress CY7C67300

CY7C67300

Document #: 38-08015 Rev. *J Page 31 of 99

The Host n Count register is used to hold the number of bytes

(packet length) for the current transaction. The maximum packet

length is 1023 bytes in ISO mode. The Host Count value is used

to determine how many bytes to transmit, or the maximum

number of bytes to receive. If the number of received bytes is

greater then the Host Count value then an overflow condition is

flagged by the Overflow bit in the Host n Endpoint Status register.

Port Select (Bit 14)

The Port Select bit selects which of the two active ports is

selected and is summarized in Tabl e 51.

1: Port 1B or Port 2B is enabled

0: Port 1A or Port 2A is enabled

Count (Bits [9:0])

The Count field sets the value for the current transaction data

packet length. This value is retained when switching between

host and device mode, and back again.

Reserved

Write all reserved bits with ’0’.

Host n Endpoint Status Register [R]

■Host 1 Endpoint Status Register 0xC086

■Host 2 Endpoint Status Register 0xC0A6

The Host n Endpoint Status register is a read only register that

provides status for the last USB transaction.

Overflow Flag (Bit 11)

The Overflow Flag bit indicates that the received data in the last

data transaction exceeded the maximum length specified in the

Host n Count register. The Overflow Flag must be checked in

response to a Length Exception signified by the Length

Exception Flag set to ‘1’.

1: Overflow condition occurred

0: Overflow condition did not occur

Underflow Flag (Bit 10)

The Underflow Flag bit indicates that the received data in the last

data transaction was less than the maximum length specified in

the Host n Count register. The Underflow Flag must be checked

in response to a Length Exception signified by the Length

Exception Flag set to ‘1’.

1: Underflow condition occurred

0: Underflow condition did not occur

Stall Flag (Bit 7)

The Stall Flag bit indicates that the peripheral device replied with

a Stall in the last transaction.

1: Device returned Stall

0: Device did not return Stall

NAK Flag (Bit 6)

The NAK Flag bit indicates that the peripheral device replied with

a NAK in the last transaction.

1: Device returned NAK

0: Device did not return NAK

Length Exception Flag (Bit 5)

The Length Exception Flag bit indicates that the received data in

the data stage of the last transaction does not equal the

maximum Host Count specified in the Host n Count register. A

Length Exception can either mean an overflow or underflow and

the Overflow and Underflow flags (bits 11 and 10, respectively)

must be checked to determine which event occurred.

1: An overflow or underflow condition occurred

0: An overflow or underflow condition did not occur

Table 51. Port Select Definition

Port Select Host/Device 1

Active Port Host/Device 2

Active Port

0AA

1BB

Table 52. Host n Endpoint Status Register

Bit # 15 14 13 12 11 10 9 8

Field Reserved Overflow

Flag Underflow

Flag Reserved

Read/Write - - - - R R - -

Default 00000000

Bit # 76543210

Field

Stall

Flag NAK

Flag Length

Exception

Flag

Reserved Sequence

Status Timeout

Flag Error

Flag ACK

Flag

Read/Write RRR- RRRR

Default 00000000

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