Freescale Semiconductor DSP56366 8.3.13 Receive Slot Mask Registers (RSMA, RSMB)

ESAI Programming Model
DSP56366 24-Bit Digital Signal Processor User Manual, Rev. 4
8-42 Freescale Semiconductor
NOTE
When operating in normal mode, bit 0 of the mask register must be set,
otherwise no output is generated.
8.3.13 Receive Slot Mask Registers (RSMA, RSMB)
The Receive Slot Mask Registers (RSMA and RSMB) are two read/write registers used by the receiver in
network mode to determine for each slot whether to receive a data word and generate a receiver full
condition (RDF=1), or to ignore the received data. RSMA and RSMB should be considered as each
containing half of a 32-bit register RSM. See Figure 8-17 and Figure 8-18. Bit number N in RSM (RS**)
is an enable/disable control bit for receiving data in slot number N.
When bit number N in the RSM register is cleared, the data from the enabled receivers input pins are
shifted into their receive shift registers during slot number N. The data is not transferred from the receive
shift registers to the receive data registers, and neither the RDF nor the ROE flags are set. This means that
during a disabled slot, no receiver full interrupt is generated. The DSP is interrupted only for enabled slots.
When bit number N in the RSM is set, the receive sequence is as usual: data which is shifted into the
enabled receivers shift registers is transferred to the receive data registers and the RDF flag is set.
Data written to the RSM affects the next received frame. The frame being received is not affected by this
data and would comply to the last RSM setting. Data read from RSM returns the last written data.
After hardware or software reset, the RSM register is preset to $FFFFFFFF, which means that all 32
possible slots are enabled for data reception.
11109876543210
X:$FFFFBB RS11 RS10 RS9 RS8 RS7 RS6 RS5 RS4 RS3 RS2 RS1 RS0
23 22 21 20 19 18 17 16 15 14 13 12
RS15 RS14 RS13 RS12
Reserved bit - read as zero; should be written with zero for future compatibility.
Figure 8-17 RSMA Register
11109876543210
X:$FFFFBC RS27 RS26 RS25 RS24 RS23 RS22 RS21 RS20 RS19 RS18 RS17 RS16
23 22 21 20 19 18 17 16 15 14 13 12
RS31 RS30 RS29 RS28
Reserved bit - read as zero; should be written with zero for future compatibility.
Figure 8-18 RSMB Register