DSP56309EVM Freescale Semiconductor, DSP56309EVM Datasheet - Page 110

• Manufacturer Part Number: DSP56309EVM
• Description: KIT EVALUATION FOR XC56309
• Manufacturer: Freescale Semiconductor
• Type: DSPr

Specifications of DSP56309EVM

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Description/function: Audio DSPs
• Product: Audio Modules
• For Use With/related Products: DSP56309
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Host Interface (HI08)
The host can transfer one byte at a time, so a 24-bit datum would be transferred using three store
(or load) byte operations, ensuring that the data byte at host bus address $7 is written last since
this causes the transfer of the data to the DSP-side HRX. However, the host bus controller may be
sophisticated enough that the host can transfer all bytes in a single operation (instruction). For
example, in the PowerPC MPC860 processor, the General-Purpose Controller Module (GPCM)
in the memory controller can be programmed so that the host can execute a single read (load
word, LDW) or write (store word, STW) instruction to the HI08 port and cause four byte
transfers to occur on the host bus. The 32-bit datum transfer shown in Figure 6-4 has byte data xx
written to HI08 address $4, byte aa to address $5, byte bb to address $6 and byte cc to address $7
(this assumes the 24-bit datum is contained in the lower 24 bits of the host’s 32-bit data register
as shown).
A similar operation occurs when the HI08 is initialized in Big Endian mode by clearing the Host
Little Endian bit (ICR[5] = HLEND). Big Endian mode is depicted in Figure 6-5.
6-10
Host side
Host side
DSP side
DSP side
internal register
internal register
Host 32-bit
Host 32-bit
Figure 6-4. HI08 Read and Write Operations in Little Endian Mode
Figure 6-5. HI08 Read and Write Operations in Big Endian Mode
HTX/HRX Bit Number: 23
HTX/HRX Register: 23
Host bus address:
Host bus address:
Low Byte
High Byte
xx
xx
DSP56309 User’s Manual, Rev. 1
$5
$5
cc
aa
cc
aa
aa
aa
bb
$6
bb
$6
bb
bb
bb
bb
aa
cc
$7
$7
aa
cc
cc
cc
0
0
(read/write last!)
(read/write last!)
Freescale Semiconductor
High Byte
Low Byte