CMT2380F17
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6 Memory Organization
Like all 80C51 devices, the CMT2380F17 has separate address spaces for program and data memory.
The logical separation of program and data memory allows the data memory to be accessed by 8-bit
addresses, which can be quickly stored and manipulated by the 8-bit CPU.
Program memory (ROM) can only be read, not written to. There can be up to 16K bytes of program
memory. In the CMT2380F17, all the program memory are on-chip Flash memory, and without the capability
of accessing external program memory because of no External Access Enable (/EA) and Program Store
Enable (/PSEN) signals designed.
Data memory occupies a separate address space from program memory. In the CMT2380F17, there are
256 bytes of internal scratch-pad RAM and 768 bytes of on-chip expanded RAM (XRAM).
6.1
On-Chip Program Flash
Program memory is the memory which stores the program codes for the CPU to execute, as shown in
Figure 6
–1. After reset, the CPU begins execution from location 0000H, where should be the starting of the
user’s application code. To service the interrupts, the interrupt service locations (called interrupt vectors)
should be located in the program memory. Each interrupt is assigned a fixed location in the program memory.
The interrupt causes the CPU to jump to that location, where it commences execution of the service routine.
External Interrupt 0, for example, is assigned to location 0003H. If External Interrupt 0 is going to be used, its
service routine must begin at location 0003H. If the interrupt is not going to be used, its service location is
available as general purpose program memory.
The interrupt service locations are spaced at an interval of 8 bytes: 0003H for External Interrupt 0, 000BH
for Timer 0, 0013H for External Interrupt 1, 001BH for Timer 1, etc. If an interrupt service routine is short
enough (as is often the case in control applications), it can reside entirely within that 8-byte interval. Longer
service routines can use a jump instruction to skip over subsequent interrupt locations, if other interrupts are
in use.
0000H
0003H
0013H
001BH
Interrupt
Locations
Reset
000BH
8 bytes
Program
Memory
16K: 3FFFH
8K: 1FFFH
Figure 6-1. Program Memory
Содержание CMT2380F17
Страница 27: ...CMT2380F17 Rev0 1 27 347 www cmostek com 1 25 Phase Noise...
Страница 111: ...CMT2380F17 Rev0 1 111 347 www cmostek com INT2IS 1 0 Selected Port Pin of nINT2 00 P4 4 01 P3 0 10 P1 1 11 P1 6...
Страница 131: ...CMT2380F17 Rev0 1 131 347 www cmostek com Figure 16 1 Timer 0 Mode 0 Structure Figure15 2 Timer 1 Mode 0 Structure...
Страница 161: ...CMT2380F17 Rev0 1 161 347 www cmostek com Figure 16 32 Split Timer 3 Mode 1 Structure AR with Ex INT...
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Страница 246: ...CMT2380F17 Rev0 1 246 347 www cmostek com SnMIPS S0MI S1MI 1 P3 3 P4 7...
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