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/**
* AVR-8 GPIO Port implementation
* Part of AVR8js
* Reference: http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf
*
* Copyright (C) 2019, 2020, Uri Shaked
*/
import { CPU } from '../cpu/cpu';
import { u8 } from '../types';
export interface AVRPortConfig {
// Register addresses
PIN: u8;
DDR: u8;
PORT: u8;
}
export type GPIOListener = (value: u8, oldValue: u8) => void;
export const portAConfig: AVRPortConfig = {
PIN: 0x20,
DDR: 0x21,
PORT: 0x22,
};
export const portBConfig: AVRPortConfig = {
PIN: 0x23,
DDR: 0x24,
PORT: 0x25,
};
export const portCConfig: AVRPortConfig = {
PIN: 0x26,
DDR: 0x27,
PORT: 0x28,
};
export const portDConfig: AVRPortConfig = {
PIN: 0x29,
DDR: 0x2a,
PORT: 0x2b,
};
export const portEConfig: AVRPortConfig = {
PIN: 0x2c,
DDR: 0x2d,
PORT: 0x2e,
};
export const portFConfig: AVRPortConfig = {
PIN: 0x2f,
DDR: 0x30,
PORT: 0x31,
};
export const portGConfig: AVRPortConfig = {
PIN: 0x32,
DDR: 0x33,
PORT: 0x34,
};
export const portHConfig: AVRPortConfig = {
PIN: 0x100,
DDR: 0x101,
PORT: 0x102,
};
export const portJConfig: AVRPortConfig = {
PIN: 0x103,
DDR: 0x104,
PORT: 0x105,
};
export const portKConfig: AVRPortConfig = {
PIN: 0x106,
DDR: 0x107,
PORT: 0x108,
};
export const portLConfig: AVRPortConfig = {
PIN: 0x109,
DDR: 0x10a,
PORT: 0x10b,
};
export enum PinState {
Low,
High,
Input,
InputPullUp,
}
/* This mechanism allows timers to override specific GPIO pins */
export enum PinOverrideMode {
None,
Enable,
Set,
Clear,
Toggle,
}
export class AVRIOPort {
private listeners: GPIOListener[] = [];
private pinValue: u8 = 0;
private overrideMask: u8 = 0xff;
private overrideValue: u8;
private lastValue: u8 = 0;
private lastDdr: u8 = 0;
constructor(private cpu: CPU, private portConfig: AVRPortConfig) {
cpu.writeHooks[portConfig.DDR] = (value: u8) => {
const portValue = cpu.data[portConfig.PORT];
this.updatePinRegister(portValue, value);
this.writeGpio(portValue, value);
};
cpu.writeHooks[portConfig.PORT] = (value: u8) => {
const ddrMask = cpu.data[portConfig.DDR];
cpu.data[portConfig.PORT] = value;
this.updatePinRegister(value, ddrMask);
this.writeGpio(value, ddrMask);
return true;
};
cpu.writeHooks[portConfig.PIN] = (value: u8) => {
// Writing to 1 PIN toggles PORT bits
const oldPortValue = cpu.data[portConfig.PORT];
const ddrMask = cpu.data[portConfig.DDR];
const portValue = oldPortValue ^ value;
cpu.data[portConfig.PORT] = portValue;
cpu.data[portConfig.PIN] = (cpu.data[portConfig.PIN] & ~ddrMask) | (portValue & ddrMask);
this.writeGpio(portValue, ddrMask);
return true;
};
// The following hook is used by the timer compare output to override GPIO pins:
cpu.gpioTimerHooks[portConfig.PORT] = (pin: u8, mode: PinOverrideMode) => {
const pinMask = 1 << pin;
if (mode == PinOverrideMode.None) {
this.overrideMask |= pinMask;
} else {
this.overrideMask &= ~pinMask;
switch (mode) {
case PinOverrideMode.Enable:
this.overrideValue &= ~pinMask;
this.overrideValue |= cpu.data[portConfig.PORT] & pinMask;
break;
case PinOverrideMode.Set:
this.overrideValue |= pinMask;
break;
case PinOverrideMode.Clear:
this.overrideValue &= ~pinMask;
break;
case PinOverrideMode.Toggle:
this.overrideValue ^= pinMask;
break;
}
}
this.writeGpio(cpu.data[portConfig.PORT], cpu.data[portConfig.DDR]);
};
}
addListener(listener: GPIOListener) {
this.listeners.push(listener);
}
removeListener(listener: GPIOListener) {
this.listeners = this.listeners.filter((l) => l !== listener);
}
/**
* Get the state of a given GPIO pin
*
* @param index Pin index to return from 0 to 7
* @returns PinState.Low or PinState.High if the pin is set to output, PinState.Input if the pin is set
* to input, and PinState.InputPullUp if the pin is set to input and the internal pull-up resistor has
* been enabled.
*/
pinState(index: number) {
const ddr = this.cpu.data[this.portConfig.DDR];
const port = this.cpu.data[this.portConfig.PORT];
const bitMask = 1 << index;
if (ddr & bitMask) {
return this.lastValue & bitMask ? PinState.High : PinState.Low;
} else {
return port & bitMask ? PinState.InputPullUp : PinState.Input;
}
}
/**
* Sets the input value for the given pin. This is the value that
* will be returned when reading from the PIN register.
*/
setPin(index: number, value: boolean) {
const bitMask = 1 << index;
this.pinValue &= ~bitMask;
if (value) {
this.pinValue |= bitMask;
}
this.updatePinRegister(this.cpu.data[this.portConfig.PORT], this.cpu.data[this.portConfig.DDR]);
}
private updatePinRegister(port: u8, ddr: u8) {
this.cpu.data[this.portConfig.PIN] = (this.pinValue & ~ddr) | (port & ddr);
}
private writeGpio(value: u8, ddr: u8) {
const newValue = ((value & this.overrideMask) | this.overrideValue) & ddr;
const prevValue = this.lastValue;
if (newValue !== prevValue || ddr !== this.lastDdr) {
this.lastValue = newValue;
this.lastDdr = ddr;
for (const listener of this.listeners) {
listener(newValue, prevValue);
}
}
}
}
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