mg84fl54 Megawin Technology, mg84fl54 Datasheet - Page 13

• Manufacturer Part Number: mg84fl54
• Description: Full-speed Usb Micro-controller
• Manufacturer: Megawin Technology

5. Memory Organization
Like all 80C51 devices, the MG84FL54B 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 MG84FL54B, 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 MG84FL54B, there are 256
bytes of internal scratch-pad RAM and 576 bytes of on-chip expanded RAM (XRAM).
Note:
5.1. Program Memory
Program memory is the memory which stores the program codes for the CPU to execute, as shown in Fig 5-1.
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.
Fig 5-1 Program Memory
MEGAWIN
This section has no description on flash memory configuration. See
get more information.
Interrupt
Locations
Reset
3FFFH
001BH
0013H
000BH
0003H
0000H
Program
Memory
MG84FL54B Data sheet
8 bytes
20.1 Flash Memory Configuration
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