Melody Data Interrupt And Halt Mode Release; Note Concerning Halt Instruction - Oki ML63611 User Manual

ML63611 User's Manual
Chapter 3 CPU Control Functions

3.3.3 Melody Data Interrupt and Halt Mode Release

The halt mode is not released by a melody data interrupt.
The melody data interrupt is different from a conventional interrupt in that the melody data interrupt is a hardware
processing interrupt used for transfer of melody data to the melody circuit. It is not dependent on the program.
When this interrupt is generated, the instruction immediately after the HALT instruction is executed, then the
melody data is transferred to the melody circuit, and the HALT instruction is executed again. This sequence is
indicated in Figure 3-7.
System Clock
HLT (halt flag)
Melody data
request
PC flow in main
routine

3.3.4 Note Concerning HALT Instruction

As described above, the instruction immediately after the HALT instruction may be executed any number of times.
For this reason, always place an NOP instruction immediately after the HALT instruction.
(Example)
OPTION A (C): 1.5 V (3.0 V), Without regulator
circuit for LCD bias
HALT
S1 S2 S1 S2 S1 S2 S1
HALT
Halt mode
instruction
execution
n n+1
Figure 3-7 Melody Data Request Interrupt Operation
•
•
•
HALT
NOP
•
•
•
S2 S1 S2 S1 S2 S2 S2 S2
Execution of
Melody
instruction
data instruction
immediately after
transter execution
HALT instruction
(melody) n
n : HALT instruction address
(melody) : Melody data address
3 – 6
OPTION B (D): 1.5 V (3.0 V), With regulator
HALT
HALT
Halt mode
n+1
circuit for LCD bias