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6.5 Boot-up Using the HI08 Host Port
The DSP56300 core has eight bootstrap operating modes to start up after reset. As the processor
exits the Reset state the value at the external mode pins
/
are loaded into the Chip Operating Mode bits (MA, MB, MC and MD) of the
IRQD
MODD
Operating Mode Register (OMR). These bits determine the bootstrap operating mode. Modes C,
D, E and F use the HI08 host port to bootstrap the application code to the DSP. Table 6-7
describes these modes.
Mode
MODD
C
1
D
1
E
1
F
1
The bootstrap program is factory-programmed into an internal 192-word by 24-bit bootstrap
ROM at locations $FF0000–$FF00BF of P memory. This program can load program RAM
segment from the HI08 host port. When any of the modes in the preceding table are used, the core
begins executing the bootstrap program and configures the HI08 based on the OMR mode bits.
The bootstrap program then expects the following data sequence when the user program is
downloaded from the HI08:
Three bytes (least significant byte first) indicating the number of 24-bit program words
1.
to be loaded.
Three bytes (least significant byte first) indicating the 24-bit starting address in
2.
P-memory to load the user's program.
3.
The user program (three bytes, least significant byte first, for each program word).
Once the bootstrap program finishes loading the specified number of words, it jumps to the
specified starting address and executes the loaded program.
6.6 DSP Core Programming Model
The DSP56300 core treats the HI08 as a memory-mapped peripheral occupying eight 24-bit
words in X data memory space. The DSP can use the HI08 as a normal memory-mapped
peripheral, employing either standard polled or interrupt-driven programming techniques.
Separate transmit and receive data registers are double-buffered to allow the DSP and host
processor to transfer data efficiently at high speed. Direct memory mapping allows the
DSP56311 core to communicate with the HI08 registers using standard instructions and
Freescale Semiconductor
Table 6-7. HI08 Boot Modes
MODC
MODB
MODA
1
0
1
0
1
1
1
1
DSP56311 User's Manual, Rev. 2
/
IRQA,
MODA
HI08 Bootstrap Description
0
ISA/DSP5630x mode
1
HC11 non-multiplexed bus mode
0
8051 multiplexed bus mode
1
MC68302 bus mode
Boot-up Using the HI08 Host Port
/
,
/
IRQB
IRQC
MODB
MODC
and
6-11
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