MK50H25DIP datasheet(42/64 Pages) STMICROELECTRONICS

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4.4.8 Link Reset

The following procedure should be followed to reset an established link.

1. Issue a Reset Request primitive (UPRIM=8).

2. Wait for a Reset Confirmation primitive (PPRIM=9) from the MK50H25 (indicating reception of UA

frame in response to SABM sent).

3. If a Reset Confirmation primitive is received, a link has been reset.

4. If a Disconnect Indication primitive (PPRIM=14) is received, the MK5025 was unable to reset the link.

The reason will be in the PPARM field of CSR1. Link connection procedures now must be performed

to re-establish the link.

4.4.9 Receiving Link Reset

The following procedure should be followed when receiving a request for link reset:

1. A Reset Indication primitive (PPRIM=8) will be received from the MK50H25 indicating the remote sta-

tion has requested a resetting of the link.

2. If able to reset, issue a Reset Response primitive (UPRIM=9) to indicate willingness to reset the link.

3. If unable to reset, issue a Disconnect Request primitive (UPRIM=14) to disconnect the link.

4.4.10 Receiving FRMR Frame

The following procedure should be followed when receiving a FRMR frame:

1. An Error Indication primitive (PPRIM=4) will be received from the MK50H25 indicating an error condi-

tion. PPARM=2 will indicate a FRMR has been received. The I-field of the FRMR has been placed in

the receive buffer pointed to by the next available Receive Descriptor.

2. If able to reset the link, issue a Reset Response primitive (UPRIM=9) and wait for either a Reset Indi-

cation or a Disconnect Indication as described previously for Link Reset.

3. If unable to reset, issue a Disconnect Request primitive (UPRIM=14) to disconnect the link. Link con-

nection procedures now must be performed to re-establish the link.

4.4.11 Exchanging Identification

The following procedure should be followed to exchange identification with the remote station:

1. The XIDE bit in CSR2 must be set prior to any identification exchange.

2. Place appropriate identification information in the XID/TEST Transmit buffer.

3. Issue an XID Request primitive (UPRIM=10)

4. If an XID Confirmation primitive (PPRIM=11) is received, the identification exchange has been per-

formed, and the remote response is located in the XID/TEST Receive buffer.

4.4.12 Receiving XID/TEST Frames

The following procedure should be performed when receiving XID/TEST frames:

1. A XID Indication primitive (PPRIM=10) or TEST Indication Primitive (PPRIM=12) will be received from

the MK50H25 to indicate the reception of a XID or TEST frame. The information field of the received

XID or TEST frame will be located in the XID/TEST receive buffer.

2. To respond, place the appropriate information in the XID/TEST transmit buffer and issue a XID/TEST

Response Primitive (UPRIM=11/13).

3. To refuse, issue a Disconnect Request primitive (UPRIM=14).

NOTE: A XID or TEST Indication primitive will only be issued if the XIDE bit is set in CSR2. Otherwise all

XID/TEST frames will automatically be refused and not recognized.

4.4.13 Disabling the MK50H25

The following procedure should be followed to disable the MK50H25:

1. Issue the STOP primitive through CSR1. This will disable the MK50H25 from receiving or transmitting.

The TD pin will be held high while the MK50H25 is in the Stopped mode. The STOP bit in CSR0 will

be set and interrupts will be disabled. If reception or transmission of a frame is in progress, then re-

ceived data may be lost, and the transmitted frame will be aborted.

4.4.14 Re-enabling the MK50H25

The same procedure should be followed for re-enabling the MK50H25 as was used to initalize upon

power up. If the Initialization Block and the hardware configuration have not changed, then steps 1,2,3,

4 and 5 of the intialization sequence may be omitted.

MK50H25

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