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SIGNAL DESCRIPTIONS AND OPERATING MODES
MOTOROLA
TECHNICAL DATA
2-9
2
If the part is not in security mode (or has completed the above erase sequence), a
break character is output by the SCI transmitter. For normal use of the boot loader pro-
gram, the user sends $FF to the SCI receiver at either E clock/16 (7812 baud for E
clock = 2 MHz) or E clock/104 (1200 baud for E clock = 2 MHz).
NOTE
This $FF is not echoed through the SCI transmitter.
Now the user must download 256 bytes of program data to be put into RAM starting
at location $0000. These characters are echoed through the transmitter. When loading
is complete, the program jumps to location $0000 and begins executing that code.
If the SCI transmitter pin is to be used, an external pull-up resistor is required because
port D pins are configured for wire-OR operation.
In special bootstrap operating mode the interrupt vectors are directed to RAM as
shown in Table 2-3. This allows the user to use interrupts by way of a jump table. For
example: to use the SWI interrupt, a jump instruction would be placed in RAM at loca-
tions $00F4, $00F5, and $00F6. When an SWI is encountered, the vector (which is in
the boot loader ROM program) will direct program control to location $00F4 in RAM
which in turn contains a JUMP instruction to the interrupt service routine.
Table 2-3 Bootstrap Mode Interrupt Vectors
Address
Vector
00C4
SCI
00C7
SPI
00CA
Pulse Accumulator Input Edge
00CD
Pulse Accumulator Overflow
00D0
Timer Overflow
00D3
Timer Output Compare 5
00D6
Timer Output Compare 4
00D9
Timer Output Compare 3
00DC
Timer Output Compare 2
00DF
Timer Output Compare 1
00E2
Timer Input Capture 3
00E5
Timer Input Capture 2
00E8
Timer Input Capture 1
00EB
Real Time Interrupt
00EE
IRQ
00F1
XIRQ
00F4
SWI
00F7
Illegal Opcode
00FA
COP Fail
00FD
Clock Monitor
BF40
(Boot)
Reset
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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