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- /* Copyright (C) 2012 by Jacob Alexander
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
- // ----- Includes -----
-
- // AVR Includes
- #include <avr/interrupt.h>
- #include <avr/io.h>
- #include <util/delay.h>
-
- // Project Includes
- #include <led.h>
- #include <print.h>
-
- // Local Includes
- #include "scan_loop.h"
-
-
-
- // ----- Defines -----
-
- // Pinout Defines
- #define DATA_PORT PORTC
- #define DATA_DDR DDRC
- #define DATA_PIN 7
- #define DATA_OUT PINC
-
- #define CLOCK_PORT PORTC
- #define CLOCK_DDR DDRC
- #define CLOCK_PIN 6
-
- #define RESET_PORT PORTF
- #define RESET_DDR DDRF
- #define RESET_PIN 7
-
-
- // ----- Macros -----
-
- // Make sure we haven't overflowed the buffer
- #define bufferAdd(byte) \
- if ( KeyIndex_BufferUsed < KEYBOARD_BUFFER ) \
- KeyIndex_Buffer[KeyIndex_BufferUsed++] = byte
-
-
-
- // ----- Variables -----
-
- // Buffer used to inform the macro processing module which keys have been detected as pressed
- volatile uint8_t KeyIndex_Buffer[KEYBOARD_BUFFER];
- volatile uint8_t KeyIndex_BufferUsed;
- volatile uint8_t KeyIndex_Add_InputSignal; // Used to pass the (click/input value) to the keyboard for the clicker
-
- volatile uint8_t currentWaveState = 0;
- volatile uint8_t currentWaveDone = 0;
- volatile uint8_t positionCounter = 0;
-
-
- // Buffer Signals
- volatile uint8_t BufferReadyToClear;
-
-
-
- // ----- Function Declarations -----
-
- void processKeyValue( uint8_t keyValue );
- void removeKeyValue( uint8_t keyValue );
-
-
-
- // ----- Interrupt Functions -----
-
- // Generates a constant external clock
- ISR( TIMER1_COMPA_vect )
- {
- if ( currentWaveState )
- {
- CLOCK_PORT &= ~(1 << CLOCK_PIN);
- currentWaveState--; // Keeps track of the clock value (for direct clock output)
- currentWaveDone--; // Keeps track of whether the current falling edge has been processed
- positionCounter++; // Counts the number of falling edges, reset is done by the controlling section (reset, or main scan)
- }
- else
- {
- CLOCK_PORT |= (1 << CLOCK_PIN);
- currentWaveState++;
- }
- }
-
-
-
- // ----- Functions -----
-
- // Setup
- inline void scan_setup()
- {
- // Setup Timer Pulse (16 bit)
-
- // TODO Clock can be adjusted to whatever (read chip datasheets for limits)
- // This seems like a good scan speed, as there don't seem to be any periodic
- // de-synchronization events, and is fast enough for scanning keys
- // Anything much more (100k baud), tends to cause a lot of de-synchronization
- // 16 MHz / (2 * Prescaler * (1 + OCR1A)) = 10k baud
- // Prescaler is 1
- cli();
- TCCR1B = 0x09;
- OCR1AH = 0x03;
- OCR1AL = 0x1F;
- TIMSK1 = (1 << OCIE1A);
- CLOCK_DDR = (1 << CLOCK_PIN);
- sei();
-
-
- // Initially buffer doesn't need to be cleared (it's empty...)
- BufferReadyToClear = 0;
-
- // Reset the keyboard before scanning, we might be in a wierd state
- scan_resetKeyboard();
- }
-
-
- // Main Detection Loop
- // Since this function is non-interruptable, we can do checks here on what stage of the
- // output clock we are at (0 or 1)
- // We are looking for a start of packet
- // If detected, all subsequent bits are then logged into a variable
- // Once the end of the packet has been detected (always the same length), decode the pressed keys
- inline uint8_t scan_loop()
- {
- // Read on each falling edge/after the falling edge of the clock
- if ( !currentWaveDone )
- {
- // Sample the current value 50 times
- // If there is a signal for 40/50 of the values, then it is active
- // This works as a very simple debouncing mechanism
- // XXX Could be done more intelligently:
- // Take into account the frequency of the clock + overhead, and space out the reads
- // Or do something like "dual edge" statistics, where you query the stats from both rising and falling edges
- // then make a decision (probably won't do much better against the last source of noise, but would do well for debouncing)
- uint8_t total = 0;
- uint8_t c = 0;
- for ( ; c < 50; c++ )
- if ( DATA_OUT & (1 << DATA_PIN) )
- total++;
-
-
- // Only use as a valid signal
- if ( total >= 40 )
- {
- // Reset the scan counter, all the keys have been iterated over
- // Ideally this should reset at 128, however
- // due to noise in the cabling, this often moves around
- // The minimum this can possibly set to is 124 as there
- // are keys to service at 123 (0x78)
- // Usually, unless there is lots of interference,
- // this should limit most of the noise.
- if ( positionCounter >= 124 )
- {
- positionCounter = 0;
-
- // Clear key buffer
- KeyIndex_BufferUsed = 0;
- }
- // Key Press Detected
- else
- {
- char tmp[15];
- hexToStr( positionCounter, tmp );
- dPrintStrsNL( "Key: ", tmp );
-
- bufferAdd( positionCounter );
- }
- }
-
- // Wait until the next falling clock edge for the next DATA scan
- currentWaveDone++;
- }
-
- // Check if the clock de-synchronized
- // And reset
- if ( positionCounter > 128 )
- {
- char tmp[15];
- hexToStr( positionCounter, tmp );
- erro_dPrint( "De-synchronization detected at: ", tmp );
- errorLED( 1 );
-
- positionCounter = 0;
- KeyIndex_BufferUsed = 0;
-
- // A keyboard reset requires interrupts to be enabled
- sei();
- scan_resetKeyboard();
- cli();
- }
-
- // Regardless of what happens, always return 0
- return 0;
- }
-
- // Send data
- uint8_t scan_sendData( uint8_t dataPayload )
- {
- return 0;
- }
-
- // Signal KeyIndex_Buffer that it has been properly read
- void scan_finishedWithBuffer( void )
- {
- }
-
- // Signal that the keys have been properly sent over USB
- void scan_finishedWithUSBBuffer( void )
- {
- }
-
- // Reset/Hold keyboard
- // NOTE: Does nothing with the HP150
- void scan_lockKeyboard( void )
- {
- }
-
- // NOTE: Does nothing with the HP150
- void scan_unlockKeyboard( void )
- {
- }
-
- // Reset Keyboard
- void scan_resetKeyboard( void )
- {
- info_print("Attempting to synchronize the keyboard, do not press any keys...");
- errorLED( 1 );
-
- // Do a proper keyboard reset (flushes the ripple counters)
- RESET_PORT |= (1 << RESET_PIN);
- _delay_us(10);
- RESET_PORT &= ~(1 << RESET_PIN);
-
- // Delay main keyboard scanning, until the bit counter is synchronized
- uint8_t synchronized = 0;
- while ( !synchronized )
- {
- // Read on each falling edge/after the falling edge of the clock
- if ( !currentWaveDone )
- {
- // Read the current data value
- if ( DATA_OUT & (1 << DATA_PIN) )
- {
- // Check if synchronized
- // There are 128 positions to scan for with the HP150 keyboard protocol
- if ( positionCounter == 128 )
- synchronized = 1;
-
- positionCounter = 0;
- }
-
- // Wait until the next falling clock edge for the next DATA scan
- currentWaveDone++;
- }
- }
-
- info_print("Keyboard Synchronized!");
- }
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