MK50H25DIP datasheet(40/64 Pages) STMICROELECTRONICS

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MK50H25 STATUS BUFFER

FIELD

DESCRIPTION

V(r)

Current value of the Receive Count Variable. 0 < V(r) < 7

(0 < V(r) < 127 for extended control).

V(s)

Current value of the Transmit Count Variable. 0 < V(s) < 7

(0 < V(s) < 127 for extended control).

V(A)

Current value of Transmit Acknowledge Count. This field contains the

value of the N(r) of the most recently received S or I frame.

The

modulo difference between V(A) and V(s) determines the number of

outstanding I frames that have not been acknowledged by the remote

station.

LOCAL STATE

Indicates the current state of operation for the local (secondary) station.

Normal Data Transfer State

Local Busy State

REJ Sent State

DISC Sent State

Normal Disconnected State

SABM/E sent for link connection

FRMR Sent State

SABM/E sent for link reset

Error Indication issued

REMOTE STATE

Indicates the current state of operation for the remote station.

Remote Not Busy

Remote Busy

PHASE

Indicates the current phase of operation for the local station.

-1:

Stopped, TD is held at 1’s, RD is ignored

Information Transfer State

Disconnected Phase, TD transmits flags

Resetting Phase

Transparent Data Transfer Phase

MERR reset phase

Revision Indicator

Indicates Firmware Revision of the device. This closely corresponds

to the ”REV XXX” label branded on the package of the device.

CURRD<23:0>

Current Receive Descriptor. This pointer indicates the position of the

descriptor for the next receive buffer to be filled.

CURRXD<23:0>

Current Transmit Descriptor. This pointer indicates the position of the

descriptor for the next transmit buffer to be transmitted.

4.4 Detailed Programming Procedures

4.4.1 Initialization (Reading of Initialization Block)

The following procedure should be followed to intialize the MK50H25:

1. Setup bus control information in CSR4.

2. Setup the Initialization Block and Desciptor Rings.

3. Load the address of the initialization block information into CSR’s 2 and 3.

4. Issue the INIT primitive through CSR1 (write 4200H to CSR1) instructing the MK50H25 to read the

initialization block pointed to by CSR’s 2 and 3.

5. Wait for the INIT confirmation primitive (CSR1 = 0242H) from the MK50H25.

Then clear the PAV bit in CSR1 (write 0040H to CSR1).

6. Issue the Start primitive through CSR1 (write 4300H to CSR1).

Flags will now be continously transmitted.

7. Enable interrupts in CSR0 if desired.

MK50H25

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