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/*
** Copyright (C) 2015 Klaus Rudolph <lts-rudolph@gmx.de>
**
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU General Public License for more details.
**
** You should have received a copy of the GNU General Public License along
** with this program; if not, write to the Free Software Foundation, Inc.,
** 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA..
**
*/
#include <avr/io.h>
#include <avr/interrupt.h>
// PA0 -> output, toggles programaticaly in 4 states, see below
// PA1 -> output, as above, will not be connected, only for scope
// PA2 -> input, drives then other PIN
// PA3 -> output, is driven indirect from previous PIN
// PA4 -> shows that the driver is active ( not tri-state or PullUp )
// PA5 -> shows the logic lever of PORT independend of driver
void Init()
{
DDRA = 0x20|0x10|0x08|0x2|0x01; // Pin 0,1,3,4,5 output
}
void WaitAndMirror()
{
for ( int i = 0; i<10; i++)
{
// Read Pin 2
bool pin = PINA & 4;
// Mirror to Pin 3
PORTA = (PORTA & ( 0xff - ( 1 << 3) )) | ( pin << 3);
}
}
int main()
{
Init();
// the loop drives PIN 0+1 to 4 states. Verilog has to calculate the results of all combinations
// of low,high,tristate and pull up.
while (1)
{
DDRA &= 0xff - 0x03; // drive to TriState
PORTA &= 0xff - 0x10; // shows driver is disabled
WaitAndMirror();
PORTA |= 0x20|0x03; // drive PullUp
WaitAndMirror();
DDRA |= 0x03; // drive Port to 1
PORTA |= 0x10; // show that our driver is enabled
WaitAndMirror();
PORTA &= 0xff - ( 0x20| 3); // drive Port to 0
WaitAndMirror();
};
}
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