INTRODUCTION
MOTOROLA
BOOTSTRAP AND ROM CODE
A - 3
A.1
INTRODUCTION
This section presents the Bootstrap program contained in the DSP56002 64-word Boot
ROM. This program can load the internal program RAM starting at P:$0 from an external
EPROM or the Host Interface, and may load any program RAM segment from the SCI
serial interface.
If MC:MB:MA=001, the program loads the internal program RAM from 1,536 consecutive
byte-wide P memory locations, starting at P:$C000 (bits 7-0). These will be packed into
512 24-bit words and stored in contiguous program RAM memory locations starting at
P:$0. After assembling one 24-bit word, the bootstrap program stores the result in inter-
nal program RAM memory. Note that the routine loads data starting with the least signifi-
cant byte of P:$0.
If MC:MB:MA=10x, the program loads internal program RAM from the Host Interface, start-
ing at P:$0. If only a portion of the P memory is to be loaded, the Host Interface bootstrap
load program may be stopped by setting Host Flag 0 (HF0). This will terminate the boot-
strap loading operation and start executing the loaded program at location P:$0 of the
internal program RAM.
If MC:MB:MA=11x, the program loads program RAM from the SCI interface. The number
of program words to be loaded and the starting address must be specified. The SCI boot-
strap code expects to receive 3 bytes specifying the number of program words, 3 bytes
specifying the address in internal program RAM to start loading the program words and
then 3 bytes for each program word to be loaded. The number of words, the starting
address and the program words are received least significant byte first followed by the
mid and then by the most significant byte. After receiving the program words, program
execution starts at the same address where loading started. The SCI is programmed to
work in asynchronous mode with 8 data bits, 1 stop bit and no parity. The clock source is
external and the clock frequency must be 16x the baud rate. After each byte is received,
it is echoed back through the SCI transmitter.
The bootstrap program listing is shown in Figure A-1.
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