FX919AD2 datasheet(19/44 Pages) CMLMICRO

19 / 44 page

4-Level FSK Modem Data Pump

FX919A

D/919A/4

TIB: Transmit Intermediate Block

This task takes 12 bytes of data from the Data Block Buffer, updates the 4-byte CRC2 checksum for inclusion

in the 'Last' block, translates the 12 data bytes to 4-level symbols (with FEC), interleaves the symbols and

transmits the result as a formatted 'Intermediate' Block.

Once the modem has read the data bytes from the Data Block Buffer, the BFREE and IRQ bits of the Status

TLB: Transmit Last Block

This task takes 8 bytes of data from the Data Block Buffer, updates and appends the 4-byte CRC2 checksum,

translates the resulting 12 bytes to 4-level symbols (with FEC), interleaves the symbols and transmits the result

as a formatted 'Last' Block.

Once the modem has read the data bytes from the Data Block Buffer, the BFREE and IRQ bits of the Status

T4S: Transmit 4 Symbols

This command is similar to T24S but takes only one byte from the Data Block Buffer, transmitting it as four 4-

level symbols.

RESET: Stop any current action

This 'task' takes effect immediately, and terminates any current action (task, AQSC or AQLEV) the modem may

be performing and sets the BFREE bit of the Status Register to '1', without setting the IRQ bit. It should be used

when VDD is applied, to set the modem into a known state.

Note that due to delays in the transmit filter, it will take several symbol times for any change to appear at the

TXOP pin.

FX919AD2 Datasheet(PDF) 19 Page - CML Microcircuits