Freescale Semiconductor MCF5480 - Manual (Page 775)

Memory Map/Register Definition
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 26-13
3–2 TXC Field (This field selects a single command)
00 N O A CTION
T AKEN
The transmitter stays in its current mode.
01 T RANSMITTER
E NABLE
This command enables operation of the transmitter. If the transmitter is already enabled, this
command has no effect.
• In UART and SIR mode, the TxEMP and TxRDY bits in PSCSR are also asserted.
• In modem, MIR and FIR mode, TxFIFO can be loaded while the transmitter is disabled unlike
UART and SIR mode. Therefore TxRDY behaves the same whether the transmitter is enabled
or not, and is not automatically set when the transmitter is enabled. The URERR bit is also not
automatically set by enabling the transmitter.
• In modem8 and modem16 mode, if no data has been written into the TxFIFO before getting the
first frame sync after enabling the transmitter, URERR will be set.
• In AC97 mode, URERR will be set if
-- the TxFIFO is empty and the transmitter is enabled and
-- the ‘Codec Ready’ condition has been detected by the receiver and
-- a frame sync occurs before any samples have been written into the TxFIFO.
10 T RANSMITTER
D ISABLE
This command terminates transmitter operation. If the transmitter is already disabled, this
command has no effect.
• In UART and SIR mode, the TxEMP and TxRDY bits are negated.
• In modem, MIR and FIR mode, the TxRDY bit remains as the current condition.
• In UART, modem and SIR mode, if a character is being transmitted when the transmitter
becomes disabled, the transmission of the character is completed before the transmitter
becomes inactive.
• In MIR and FIR mode, if the transmitter is sending and there are any characters in the TxFIFO
when the transmitter becomes disabled, the transmitter continues sending data until the last
byte (data with EOF mark) in the current frame.
11 — Reserved, do not use.
Table 26-7. PSCCRn Field Descriptions (Continued)
Bits Value Command Description