DSP56303 Datasheet, PDF (161/292 Pages) Freescale Semiconductor, Inc – DSP56303 USER’S MANUAL

ESSI Programming Model
unused. Unused bits are read as 0. Data shifts out of these registers MSB first if the SHFD bit is
cleared and LSB first if SHFD is set.
23
16 15
87
Receive High Byte
Receive Middle Byte Receive Low Byte
7
07
07
Serial ²³
16 15
87
Receive _{Receive High Byte}
Shift
Receive Middle Byte Receive Low Byte
Register ⁷
07
07
0
ESSI Receive Data
Register
0
0
0
24 Bit
STD
MSB
LSB
8-bit Data
0
MSB
LSB
12-bit Data
MSB
16-bit Data
16 Bit
12 Bit
8 Bit
WL1, WL0
0
0
LSB
SRD
Least Significant
Zero Fill
MSB
LSB
24-bit Data
(a) Receive Registers
NOTES:
Data is received MSB first if SHFD = 0.
24-bit fractional format (ALC = 0).
32-bit mode is not shown.
23
16 15
87
0
ESSI Transmit Data
Transmit High Byte
Transmit Middle Byte Transmit Low Byte Register
7
07
07
0
23
16 15
07
Transmit High Byte
Transmit Middle Byte Transmit Low Byte
7
07
07
0
ESSI Transmit
Shift Register
0
MSB
LSB
8-bit Data
0
0
0
MSB
12-bit Data
LSB
MSB
16-bit Data
LSB
Least Significant
Zero Fill
MSB
LSB
24-bit Data
(b) Transmit Registers
NOTES:
Data is transmitted MSB first if
SHFD = 0. 4-bit fractional format (ALC = 0).
32-bit mode is not shown.
Figure 7-12. ESSI Data Path Programming Model (SHFD = 0)
Freescale Semiconductor
DSP56303 User’s Manual, Rev. 2
7-29