feat(timer): Compare Match Output (#45)

The Compare Match Output bits are used to generate hardware PWM signals on selected MCU pins. This is also the mechanism used by Arduino's analogWrite() method.

See #32 for more details

1 files changed, 4 insertions, 0 deletions

diff --git a/src/cpu/cpu.ts b/src/cpu/cpu.ts
index 5663a1c..ed88e71 100644
--- a/src/cpu/cpu.ts
+++ b/src/cpu/cpu.ts
@@ -44,6 +44,7 @@ export type CPUMemoryReadHook = (addr: u16) => u8;
 export interface CPUMemoryReadHooks {
   [key: number]: CPUMemoryReadHook;
 }
+
 export class CPU implements ICPU {
   readonly data: Uint8Array = new Uint8Array(this.sramBytes + registerSpace);
   readonly data16 = new Uint16Array(this.data.buffer);
@@ -53,6 +54,9 @@ export class CPU implements ICPU {
   readonly writeHooks: CPUMemoryHooks = [];
   readonly pc22Bits = this.progBytes.length > 0x20000;
 
+  // This lets the Timer Compare output override GPIO pins:
+  readonly gpioTimerHooks: CPUMemoryHooks = [];
+
   pc = 0;
   cycles = 0;