Receive Slot Mask Registers (Rsma, Rsmb) - Freescale Semiconductor DSP56311 User Manual

7.5.10 Receive Slot Mask Registers (RSMA, RSMB)

Both receive slot mask registers are read/write registers. In Network mode, the receiver(s) use
these registers to determine which action to take in the current time slot. Depending on the setting
of the bits, the receiver(s) either tri-state the receiver(s) data signal(s) or receive a data word and
generate a receiver full condition.
23 22 21
11 10 9
RS11 RS10 RS9
—Reserved bit; read as 0; write to 0 0 for future compatibility.
Figure 7-16. ESSI Receive Slot Mask Register A (RSMA)
23 22 21
11 10 9
RS27 RS26 RS25
–Reserved. Read as zero. Write with zero for future compatibility.
Figure 7-17. ESSI Receive Slot Mask Register B (RSMB)
RSMA and RSMB (as in Figure 7-12 and Figure 7-13) can be seen as one 32-bit register, RSM.
Bit n in RSM (RSn) is an enable/disable control bit for time slot number N. When RSn is cleared,
all the data signals of the enabled receivers are tri-stated during time slot number N. Data
transfers from the receive data register(s) to the receive shift register(s), but the RDF and ROE
flags are not set. Consequently, during a disabled slot, no receiver full interrupt is generated. The
DSP is interrupted only for enabled slots. When RSn is set, the receive sequence proceeds
normally. Data is received during slot number N, and the RDF flag is set.
When the bits in the RSMx are set, the frame being transmitted is unaffected, but the next frame
transmission is affected. If the RSMx is read, it shows the current setting. When the internal data
bus reads RSMA or RSMB, the register contents occupy the two low-order bytes of the data bus,
and the high-order byte is filled by 0.
After a hardware
RESET
$FFFFFFFF, enabling all 32 time slots for data transmission.
Freescale Semiconductor
20 19 18
8 7 6
RS8 RS7 RS6
(ESSI0 X:$FFFFB2, ESSI1 X:$FFFFA2)
20 19 18
8 7 6
RS24 RS23 RS22
(ESSI0 X:$FFFFB1, ESSI1 X:$FFFFA1)
signal or a software RESET instruction, the RSM register is reset to
DSP56311 User's Manual, Rev. 2
17 16 15
RS15
5 4 3
RS5 RS4 RS3
17 16 15
RS31
5 4 3
RS21 RS20 RS19
ESSI Programming Model
14 13 12
RS14 RS13 RS12
2 1 0
RS2 RS1 RS0
14 13 12
RS30 RS29 RS28
2 1 0
RS18 RS17 RS16
7-33