
2.1 CPU
33
(2) Register Bank Pointer (RP)
The RP register indicates the relationship between the general purpose registers of the F2MC-16F core
and internal RAM. The first memory address of the register bank currently in use is indicated using the
conversion formula [000180H + (RP) * 10H]. The RP register has 5-bit configuration and can take val-
ues from 00h to 1Fh corresponding to register banks having memory addresses 000180H to 00037FH.
For a description of the relation between the RP register and internal RAM, as well as the configuration
of register banks, see the description of general-purpose registers.
Instruction execution can transfer 8-bit immediate data values to the RP register, but only the lower 5
bits can be actually used. Following a reset, this register is initialized to the value 00H.
Fig. 2.1.17 Register Bank Pointer
(3) Interrupt Level Mask Register (ILM)
The ILM register has 3-bit configuration, and indicates the level of CPU interrupt masking. To be
received by the CPU, interrupt requests must have a stronger (higher) level than the setting of these
three bits. The strongest (highest priority) level is 0 and the weakest (lowest priority) level is 7 (see
Table 2.1.4). Thus for an interrupt to be received, it must be requested at a level with a smaller value
than the current ILM register value. When an interrupt is received, the value of its level is stored in the
ILM register, and no interrupts of equal or lower priority will then be received.
Instruction execution can transfer 8-bit immediate data values to the ILM register, but only the lower
three bits can be actually used. Following a reset, this register is initialized to the value '0.'
Fig. 2.1.18 Interrupt Level Register
Table 2.1.4 Relative Strength (Priority) of Levels in the Interrupt Level Mask Register (ILM)
ILM2
ILM1
ILM0
Level value
Interrupt level enabled
0
Interrupt disabled
0
1
Level 0 only
0
1
0
2
Level 2 or stronger
0
1
3
Level 3 or stronger
1
0
4
Level 4 or stronger
1
0
1
5
Level 5 or stronger
1
0
6
Level 6 or stronger
1
7
Level 7 or stronger
B4 B3 B2 B1 B0
:RP
ILM2
ILM1
ILM0
:ILM