Bootstrap Loader Reprogram Data Or Program Memory Through Spi Port; Flowchart Of Bootstrap Loader Interrupt Service Routine - Texas Instruments TMS370 Series Application Book

Bootstrap Loader
Reprogram Data or Program Memory through SPI Port
The SPI is very useful as a bootstrap loader for loading program or data information directly into RAM,
EPROM, or EEPROM. The TMS370 family SPI and instruction set provide a fast, efficient way of moving
serial data directly into memory. With the addition of a small interrupt service routine, the memory loader
can become a bootstrap loader to reprogram a device in-socket, in the field. The interrupt routine must do
the following:
Figure 4. Flowchart of Bootstrap Loader Interrupt Service Routine
The interrupt routine loads the received data into program memory beginning at a specified location. After
the data has been loaded in, the program counter is set to the beginning of the block and program execution
is transferred to the new program. The new program can reconfigure the part as desired, or modify the
program or data memory.
CALL INTx
INITIALIZE SPI
SET COUNTER TO START OF BLOCK
WAIT FOR CHARACTER
*
MOVE CHARACTER TO
BLOCK START + COUNTER
COUNTER = COUNTER + 1
END
N
OF
DATA
Y
BRANCH TO START OF BLOCK
START EXECUTION
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