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Register Descriptions (ESSI0_BASE = $1FFE20, ESSI1_BASE = $1FFE00)
5685X Digital Signal Controller User Manual, Rev. 4
12-40
Freescale Semiconductor
12.8.8.5 Transmit Enable 0 (TE0)—Bit 12
This control bit enables the transfer of the contents of the STX0 register to its Transmit Data Shift
Register 0 (TXSR0). TE0 is functional when the ESSI is in either Synchronous or Asynchronous
modes.
0 = The transmitter continues to send the data currently in TXSR0, then disables the
transmitter.
1 = On the next frame boundary, the transmit 0 portion of the ESSI is enabled. With
internally generated clocks, the frame boundary will occur within a word time. If the TE0
bit is cleared, then set again during the same transmitted word, the data continues to be
transmitted. If the TE0 bit is set again during a different time slot, data is not transmitted
until the next frame boundary.
The serial output is tri-stated and any data present in the STX0 register is not transmitted. For
example, data can be written to the STX0 register with the TE0 bit cleared and the TDE bit is
cleared, but data is not transferred to the TXSR0.
The Normal Transmit Enable sequence is to write data to the STX0 register or to the STSR
before setting the TE0 bit. The Normal Transmit Disable sequence is to clear both the TE0 and
TIE bits after the TDE bit is set. This bit should be cleared when clearing ESSIEN.
12.8.8.6 Transmit Enable 1 (TE1)—Bit 11
This control bit enables the transfer of the contents of the STX1 register to its Transmit Data Shift
Register 1 (TXSR1). TE1 is functional when the ESSI is in the Synchronous mode. It is ignored
when the ESSI is in the Asynchronous mode.
0 = The transmitter continues to send the data currently in TXSR1, then disables the
transmitter. The serial output is tri-stated and any data present in the STX1 register is not
transmitted. In other words, data can be written to the STX1 register with the TE1 bit
cleared and the TDE bit is cleared but data is not transferred to the TXSR1.
1 = On the next frame boundary, the Transmit 1 portion of the ESSI is enabled for that
frame. With internally generated clocks, the frame boundary will occur within a word
time. If the TE1 bit is cleared and then set again during the same transmitted word, the
data continues to be transmitted. If the TE1 bit is set again during a different time slot,
data is not transmitted until the next frame boundary.
When the TE1 bit remains clear until the beginning of the next frame, it causes the SC0 signal to
act as a serial I/O flag from the start of the frame in both Normal and Network modes.
The Normal Transmit Enable sequence is to write data to the STX1 register or to the STSR
before setting the TE1 bit. The Normal Transmit Disable sequence is to clear the TE1 and TIE
bits after the TDE bit is set. This bit should be cleared when clearing ESSIEN.
Note:
Setting the TE1 bit does not affect the generation of frame sync or output flags.