ESSI Programming Model
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DSP56303 User’s Manual
7.5.5
ESSI Receive Data Register (RX)
The Receive Data Register (RX) is a 24-bit read-only register that accepts data from the
receive shift register as it becomes full, according to Figure 7-12 and Figure 7-13. The data
read is aligned according to the value of the ALC bit. When the ALC bit is cleared, the MSB
is bit 23, and the least significant byte is unused. When the ALC bit is set, the MSB is bit 15,
and the most significant byte is unused. Unused bits are read as 0. If the associated interrupt is
enabled, the DSP is interrupted whenever the RX register becomes full.
7.5.6
ESSI Transmit Shift Registers
The three 24-bit transmit shift registers contain the data being transmitted, as in Figure 7-12
and Figure 7-13. Data is shifted out to the serial transmit data signals by the selected (whether
internal or external) bit clock when the associated frame sync I/O is asserted. The word-length
control bits in CRA determine the number of bits that must be shifted out before the shift
registers are considered empty and can be written again. Depending on the setting of the
CRA, the number of bits to be shifted out can be 8, 12, 16, 24, or 32. Transmitted data is
aligned according to the value of the ALC bit. When ALC is cleared, the MSB is Bit 23 and
the least significant byte is unused. When ALC is set, the MSB is Bit 15 and the most
significant byte is 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.
Summary of Contents for DSP56303
Page 1: ...DSP56303 User s Manual 24 Bit Digital Signal Processor DSP56303UM AD Revision 1 January 2001 ...
Page 52: ...JTAG OnCE Interface 2 22 DSP56303 User s Manual ...
Page 114: ...General Purpose Input Output GPIO 5 10 DSP56303 User s Manual ...
Page 212: ...GPIO Signals and Registers 8 26 DSP56303 User s Manual ...
Page 268: ...Interrupt Equates A 22 DSP56303 User s Manual ...
Page 306: ...Programming Sheets B 38 DSP56303 User s Manual ...
Page 320: ...Index 14 DSP56303 User s Manual ...