Lantronix DSTni-EX Manual do Utilizador descarregar pdf (Página 57)

Endpoint Control Registers

The Endpoint Control registers contain the endpoint control bits for the 16 endpoints available

on USB for a decoded address. These four bits define all the control necessary for any one

endpoint. Endpoint 0 (ENDPT0) is associated with control pipe 0, which is required by USB for

all functions. Therefore, after receiving a USB_RST interrupt, the microprocessor sets ENDPT0

to contain 0Dh.

Table 4-21. Endpoint Control Registers

BIT 7 6 5 4 3 2 1 0

OFFSET

11h through 7h

FIELDS

HOST_WO_HUB

RETRY_DIS

///

EP_CTL_DIS

EP_RX_EN

EP_TX_EN

EP_STALL

EP_HSHK

RESET

0 0 0 0 0 0 0 0

R/W R/W R/W R/W R/W R/W R/W R/W

Table 4-22. Endpoint Control Register Definitions

Bits Field Name Description

7 HOST_WO_HUB

Host-Mode-Only Bit

A host-mode-only bit that is present only in the Control register for endpoint 0

(endpt0_rg).

1 = host can communicate to a directly connected low-speed device.

0 = host produces the PRE_PID, then switches to low-speed signaling to send a

token to a low-speed device. This is required to communicate with a low-speed

device through a hub.

6 RETRY_DIS

Host-Mode-Only Bit

A host-mode-only bit that is present only in the control register for endpoint 0

(endpt0_rg).

1 = prevent host retrying NAK’ed transactions. When a transaction is NAK'ed, the

NAK PID updates the BDT PID field and the token-done interrupt is set.

(Required setting when host tries to poll an interrupt endpoint.)

0 = NAK'ed transactions are retried in hardware.

5 /// Reserved

4 EP_CTL_ DIS

3 EP_RX_EN

2 EP_TX_EN

Endpoint Enable

Defines whether an endpoint is enabled and the direction of the endpoint. Table

4-23 shows the enable/direction control values.

1 EP_STALL

Endpoint Stalled

This bit has priority over all control bits in the Endpoint Enable register; however,

it is only valid if EP_IN_EN=1 or EP_OUT_EN=1. Any access to this endpoint

causes the USB to return a STALL handshake. After an endpoint stalls, it requires

intervention from the host controller.

0 EP_HSHK

Endpoint Handshaking

1 = defines whether the endpoint performs handshaking during a transaction to

this endpoint

This bit is generally set, unless it is an isochronous endpoint.

1 2 ... 52 53 54 55 56 57 58 59 60 61 62 ... 94 95

Comentários a estes Manuais

Sem comentários

Lantronix DSTni-EX Manual do Utilizador Página 57

Comentários a estes Manuais

Manuais e produtos relacionados com não Lantronix DSTni-EX