UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 552

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

20.4.2 BRKCS Instruction Software Interrupt (Software Context Switching) Acknowledgment Operation
must be in the base area) stored beforehand in the specified register bank, and the contents of the program status word
(PSW) and program counter (PC) are saved in the register bank.
must specify the start address of the interrupt service program for the next time context switching is performed by a BRKCS
instruction. This interrupt service program start address must be in the base area.
512
The context switching function can be initiated by executing a BRKCS instruction.
The register bank to be used after context switching is specified by the BRKCS instruction operand.
When a BRKCS instruction is executed, the program branches to the start address of the interrupt service program (which
The RETCSB instruction is used to return from a software interrupt due to a BRKCS instruction. The RETCSB instruction
Caution The RETCS instruction must not be used to return from a BRKCS instruction software interrupt.
2 Save
(Bits 8 to 11 of
Temporary Register)
PC
1 Save
Figure 20-7 Context Switching Operation by Execution of a BRKCS Instruction
19-16
7 Transfer
PSW
0000B
Temporary Register
6 Exchange
PC
15-0
5 Save
CHAPTER 20 INTERRUPT FUNCTIONS
W
V
U
T
Register Bank n (n = 0 to 7)
R5
R7
A
B
D
H
VP
UP
R4
R6
X
C
E
L
3 Register Bank Switching
4
(
(RBS0-RBS2
RSS
IE
0
0
)
Register Bank
n)
(0 to 7)