Interrupts: Difference between revisions

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   +----- Enable NMI on low battery detection
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Revision as of 10:53, 22 August 2023

The WonderSwan features fourteen different interrupts:

  • CPU interrupts - six provided by the V30MZ CPU ($00-$05),
  • Hardware interrupts - eight provided by the SoC's hardware ($00-$07, or $08-$0F, or $10-$1F, or ... $F8-$FF - controlled by an offset V):
    • Level - will be constantly requested while the prerequisite condition is true; interruption can only be prevented by resolving the condition or disabling the interrupt;
    • Edge - will only be requested when the prerequisite condition becomes true; acknowledging the interrupt prevents further interruption.

The user can additionally define and use any of the 256 interrupt vectors in their own code.

List of WonderSwan interrupts
Source Type Index Description
CPU N/A $00 DIV or IDIV instruction divide error

(division by zero or result overflow)

$01 Single-step (T flag)
$02 NMI (non-maskable interrupt)
$03 INT 3 opcode
$04 INTO opcode (if V = 1)
$05 BOUND opcode (if index out of bounds)
Hardware Level V + 0 UART Send Ready
Edge V + 1 Key Pressed
Level V + 2 Cartridge IRQ
V + 3 UART Receive Ready
Edge V + 4 Display Interrupt Line Match
V + 5 Vertical Blank Timer
V + 6 Display Vertical Blank
V + 7 Horizontal Blank Timer

I/O ports

Interrupt Vector

7  bit  0
---- ----
VVVV V...
|||| ||||
++++-++++- Interrupt vector offset
           (lowest three bits ignored)

Interrupt Enable

7  bit  0
---- ----
iiii iiii
|||| ||||
++++-++++- Hardware interrupt to enable
           (acts as a mask)

Interrupt Status

7  bit  0
---- ----
iiii iiii
|||| ||||
++++-++++- 1 if interrupt requested

Interrupt Acknowledge

7  bit  0
---- ----
iiii iiii
|||| ||||
++++-++++- Write 1 to clear interrupt request

Interrupt NMI Control

7  bit  0
---- ----
...b ....
   |
   +----- Enable NMI on low battery detection