User guide

8
SmartBook for Renesas R8C/Tiny Microcontrollers
www.MightyMicons.com
Interrupt Table Register (INTB): This 20-bit register
contains the address of an interrupt vector table. The
table may contain up to 63 interrupt vectors of 4 bytes
each. Using this INTB, this total interrupt space of 256
bytes (64x4) can be defined in any place in the memory
space. In addition, this interrupt vector table can be relocated
to any other place by defining this INTB.
1.5 Memory of the R8C/Tiny Devices:
As you know, all the R8C/Tiny microcontrollers operate in single chip mode
because they do not have facility to add any memory externally. Therefore, the
devices come with the required program memory and static RAM area along with
the peripheral functions. This program memory is constructed using the high
performance flash memory that varies from 8K bytes to 64K bytes. Similarly,
available RAM portion varies from 512 bytes to 4K bytes. The controller’s flash
and RAM capacity vary from device to device.
The flash memory has many special features for your convenience. The most
usable one is the In System Programming for the flash area. In other words, the
contents of the flash memory can be changed after soldering the device in the
application hardware. This is an important facility enabling you to modify your
code or the application data in the field itself. Then the internal memory
management module safeguards the flash contents under an exclusive identity
code to prevent any unauthorized reading. You can define an identity code in 7
bytes of the flash memory. Then, every time you need to match this code to
access the flash contents.
Normally Renesas devices come with more RAM area than other similar controllers.
Having a large RAM area serves many purposes. Because of the large size, you
can maintain a large stack in the RAM area. Another useful feature is, with enough
RAM space, you can easily manage in system program operations.
Now, let us see how this flash memory and the RAM area are mapped in the
device. Since the program counter is of 20 bits width, the CPU can access up to
1M Byte memory. Both the program and the data memory reside in this memory
space.
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Normally Renesas
devices come with
more RAM area
than other similar
controllers.
Because of
the large size, you can maintain
a large stack in the RAM
area.