MK50H27DIP datasheet(40/56 Pages) STMICROELECTRONICS

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4.4 Detailed Programming Procedures

4.4.1 Initialization

The following procedure should be followed to intialize the MK50H27:

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 instructing the MK50H27 to read the initialization block pointed

to by CSR’s 2 and 3.

5. Wait for the INIT confirmation primitive from the MK50H27.

6. For SS7 operation, issue the PON primitive through CSR1, SIOS’s will now be continuously transmit-

ted. For HDLC Transparent mode, issue the TRANS primitive through CSR1, flags will now be conti-

nously transmitted.

7. Enable interrupts in CSR0 if desired.

4.4.2 Alignment

1. For SS7 operation issue the START primitive through CSR1 to begin alignment.

2. Wait for the IN SERVICE provider primitive.

4.4.3 Sending Data

Use the following procedure to send a MSU:

1. Wait for the OWNA bit of the current transmit descriptor to be cleared, if it is not already.

2. Fill the buffer associated with the current transmit descriptor with the data to be sent, or set the de-

scriptor buffer address to any already filled buffer.

3. Repeat steps 1 and 2 for the next buffer if chaining is necessary, setting SLF, ELF and MCNT appro-

priately.

4. Set the OWNA bit for each descriptor used.

4.4.4 Receiving Data

The following procedure should be followed when receiving a MSU:

1. Make sure the OWNA bit of the current receive descriptor is clear.

2. Read data out of the buffer associated with the current receive descriptor.

3. Set the OWNA bit of the current receive descriptor.

4. If the ELF bit of the current receive descriptor is clear, then go on to the next descriptor and repeat

the above steps appending data from each buffer until a descriptor with the ELF bit set is reached.

4.4.5 Link Disconnection

The following procedure should be followed to disconnect an established link:

1. For SS7 operation, issue the STOP primitive through CSR1. The MK50H27 will enter the Out of

Service state and continuously transmit SIOS’s.

4.4.6 Disabling the MK50H27

The following procedure should be followed to disable the MK50H27:

1. Issue the POFF primitive through CSR1. This will disable the MK50H27 from receiving or transmit-

ting. The TD pin will be held high while the MK50H27 is in the Power Off state. The POFF bit in

CSR0 will be set and interrupts will be disabled. If a link is currently established, then data may be

lost.

4.4.7 Re-enabling the MK50H27

The same procedure should be followed for re-enabling the MK50H27 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.

MK50H27

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