Receive Slot Mask Registers (Rsma, Rsmb) - Motorola DSP56367 User Manual

Enhanced Serial Audio Interface (ESAI)
ESAI Programming Model
When bit number N in TSM is cleared, all the transmit data pins of the enabled transmitters
are tri-stated during transmit time slot number N. The data is still transferred from the transmit
data registers to the transmit shift registers but neither the TDE nor the TUE flags are set. This
means that during a disabled slot, no transmitter empty interrupt is generated. The DSP is
interrupted only for enabled slots. Data that is written to the transmit data registers when
servicing this request is transmitted in the next enabled transmit time slot.
When bit number N in TSM register is set, the transmit sequence is as usual: data is
transferred from the TX registers to the shift registers, transmitted during slot number N, and
the TDE flag is set.
Using the slot mask in TSM does not conflict with using TSR. Even if a slot is enabled in
TSM, the user may chose to write to TSR instead of writing to the transmit data registers TXx.
This causes all the transmit data pins of the enabled transmitters to be tri-stated during the
next slot.
Data written to the TSM affects the next frame transmission. The frame being transmitted is
not affected by this data and would comply to the last TSM setting. Data read from TSM
returns the last written data.
After hardware or software reset, the TSM register is preset to $FFFFFFFF, which means that
all 32 possible slots are enabled for data transmission.
Note: When operating in normal mode, bit 0 of the mask register must be set, otherwise
no output is generated.

10.3.13 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 Table 10-17 and
10-46 DSP56367 MOTOROLA