
TM1100 Preliminary Data Book
Philips Semiconductors
16-10
PRELIMINARY INFORMATION
File: ssi.fm5, modified 7/24/99
VSS
Valid Slot Size (Bit 11-8). The VSS[3:0] bits control the valid slot size starting from slot 1 for different modem analog
front end devices. The valid setup value ranges from 1 to 16 slot(s). The value 16 is accomplished by storing a 0 in
this eld.
FMS
Frame Sync Mode Select (Bit 7). The FMS bit value should only be changed when the transmitter and receiver are
disabled. FMS selects the type of frame sync to be recognized by both Rx and Tx. When FMS equals one, frame
sync is word-length bit clock. When this bit equals zero, frame sync is one-bit clock.
FSP
Frame Sync Polarity (Bit 6). The FSP bit value should only be changed when the transmitter and receiver are dis-
abled. FSP controls which edge of frame sync is the active edge for both Rx and Tx. This bit causes frame signal to
be active at rising edge when FSP equals zero, or falling edge when FSP equals one.
MOD
Mode Select (Bit 5). The MOD bit value should only be changed when the transmitter and receiver are disabled. MOD
selects the operational mode of the SSI for ISDN functionality. When MOD is set, the SSI is congured as a U-inter-
face for ISDN NT. Otherwise, set to ‘0’. Setting MOD bit and CD2 it supports the MC145574 and MC145572 ISDN
interface transceivers.
EMS
Endian Mode Select (Bit 4). EMS selects the big- or little-endian mode operation. Both these modes are explained
in more detail in section
16.8.
ILS
Interrupt Level Select (Bit 3-0). Set the point where an interrupt is generated for normal data buffer servicing. The
number is ranging from 1 to 15 of 32-bit word(s). This eld controls interrupt level of both transmit and receive func-
tions.
Table 16-5. SSI Control Register (SSI_CTL) Fields.
Field
Description
Table 16-6. IO1 Mode Select
Bit
Mode
00
General Purpose Output: Congures the SSI_IO1 pin as a general purpose output. The pin follows the state of the WIO1
eld of the SSI_CTL.
01
General Purpose Input: Change detector may be used. Value can be read in from RIO1 eld of the SSI_CSR.
10
Enable External TxCLK: Allows for use of an externally generated TxCLK. The clock is provided via the TxCLK pin. All
general purpose I/O functions are unavailable.
11
Disable: Pin is not used. Output buffer is tristated and the input is ignored. (RESET default)
Table 16-7. IO2 Mode Select
Bit
Mode
00
General Purpose Output: Congures the SSI_IO2 pin as a general purpose output. The pin follows the state of the WIO2
eld of the SSI_CTL.
01
General Purpose Input: Value can be read in from RIO2 eld of the SSI_CSR.
10
Frame Signal TxFSX (Output): Output the frame signal generated by the internal frame signal generation logic.
11
Frame Signal TxFSX (Input): Allows for use of an externally generated TxFSX. The frame sync signal is provided via
TxFSX pin. All general purpose I/O functions are unavailable. (RESET default)