DS2196 Dallas Semiconducotr, DS2196 Datasheet - Page 100

• Manufacturer Part Number: DS2196
• Description: T1 Dual Framer LIU
• Manufacturer: Dallas Semiconducotr

Four new registers were added for the enhanced functionality of the HDLC controller; RDC1, RDC2,
TDC1, and TDC2. Note that the BOC controller is functional when the HDLC controller is used for
DS0s. Section 18 contains all of the HDLC and BOC registers and information on FDL/Fs Extraction
and Insertion with and without the HDLC controller.
17.1 HDLC FOR DS0S
When using the HDLC controllers for DS0s, the same registers shown in section 18 will be used except
for the TBOC and RBOC registers and bits HCR.7, HSR.7, and HIMR.7.
As a basic guideline for interpreting and sending HDLC messages and BOC messages, the following
sequences can be applied.
Receive a HDLC Message
1. Enable RPS interrupts
2. Wait for interrupt to occur
3. Disable RPS interrupt and enable either RPE, RNE, or RHALF interrupt
4. Read RHIR to obtain REMPTY status
5. Repeat step 4
6. Wait for interrupt, skip to step 4
7. If POK=0, then discard whole packet, if POK=1, accept the packet
8. Disable RPE, RNE, or RHALF interrupt, enable RPS interrupt and return to step 1.
Transmit a HDLC Message
1. Make sure HDLC controller is done sending any previous messages and is current sending flags by
2. Enable either the THALF or TNF interrupt
3. Read THIR to obtain TFULL status
4. Repeat step 3
5. Wait for interrupt, skip to step 3
6. Disable THALF or TNF interrupt and enable TMEND interrupt
7. Wait for an interrupt, then read TUDR status bit to make sure packet was transmitted correctly.
checking that the FIFO is empty by reading the TEMPTY status bit in the THIR register
a. If REMPTY=0, then record OBYTE, CBYTE, and POK bits and then read the FIFO
b. If REMPTY=1, then skip to step 6
a. If TFULL=0, then write a byte into the FIFO and skip to next step (special case occurs when
b. If TFULL=1, then skip to step 5
a1. if CBYTE=0 then skip to step 5
a2. if CBYTE=1 then skip to step 7
the last byte is to be written, in this case set TEOM=1 before writing the byte and then skip to
step 6)
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