BT8376EPF datasheet(84/323 Pages) CONEXANT

84 / 323 page

2.0 Circuit Description

Bt8370/8375/8376

2.8 Transmitter

Fully Integrated T1/E1 Framer and Line Interface

2-56

Conexant

N8370DSE

The Transmit Data Link FIFO #1 [TDL1; addr 0AD] is 64 bytes, and very

versatile. It can be used as a single-byte transmit buffer or in any number of bytes,

up to a maximum of 64. As a single-byte FIFO, the Transmit FIFO Empty Status

(TMPTY1) in TDL #1 Status [TDL1_STAT; addr 0AE] and Transmit FIFO

Empty Interrupt (TEMPTY) in Data Link 1 Interrupt Status (ISR2; addr 009] can

be used for byte-by-byte transmissions.

Using the Transmit Data FIFO, an entire block of data can be transmitted with

very little microprocessor-interrupt overhead. Block transfers to the FIFO can be

controlled by the Near Empty Threshold in the FIFO Empty Control register

[TDL1_FEC; addr 0AB]. The Near Empty Threshold is a user-programmable

value between 0 and 63 that represents the minimum number of bytes that can

remain in the transmit FIFO before near empty is declared. Once the threshold is

set, the Near Empty Status (TNEAR1) in TDL #1 Status [TDL1_STAT;

addr 0AE] is asserted whenever the Near Empty Threshold is reached. An

interrupt, TNEAR in the Data Link 1 Interrupt Status register [ISR2; addr 009], is

also available to mark this event.

Once an entire message is written into the transmit FIFO or circular buffer, the

processor must indicate the end of message by writing any value to the TDL #1

End of Message (EOM) Control [TDL1_EOM; addr 0AC]. In FCS mode, the

EOM indicates that the FCS is to be calculated and transmitted following the last

byte in the FIFO; in the Circular Buffer mode, the EOM indicates the end of the

transmit circular buffer.

BT8376EPF Datasheet(PDF) 84 Page - Synaptics Incorporated.