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/* Copyright (C) 2012 by Jacob Alexander |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining a copy |
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* of this software and associated documentation files (the "Software"), to deal |
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* in the Software without restriction, including without limitation the rights |
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
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* copies of the Software, and to permit persons to whom the Software is |
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* furnished to do so, subject to the following conditions: |
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* |
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* The above copyright notice and this permission notice shall be included in |
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* all copies or substantial portions of the Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
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* THE SOFTWARE. |
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*/ |
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// ----- Includes ----- |
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// AVR Includes |
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#include <avr/interrupt.h> |
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#include <avr/io.h> |
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#include <util/delay.h> |
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// Project Includes |
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#include <led.h> |
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#include <print.h> |
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// Local Includes |
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#include "scan_loop.h" |
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// ----- Defines ----- |
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// Pinout Defines |
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#define REQUEST_PORT PORTD |
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#define REQUEST_DDR DDRD |
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#define REQUEST_PIN 3 |
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#define DATA_READ PIND |
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#define DATA_PORT PORTD |
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#define DATA_DDR DDRD |
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#define DATA_PIN 2 |
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#define MAX_SAMPLES 10 |
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#define MAX_FAILURES 3731 |
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#define PACKET_STORAGE 24 // At worst only 8 packets, but with you keypresses you can get more |
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// ----- Macros ----- |
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#define READ_DATA DATA_READ & (1 << DATA_PIN) ? 0 : 1 |
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#define REQUEST_DATA() REQUEST_DDR &= ~(1 << REQUEST_PIN) // Start incoming keyboard transfer |
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#define STOP_DATA() REQUEST_DDR |= (1 << REQUEST_PIN) // Stop incoming keyboard data |
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// Make sure we haven't overflowed the buffer |
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#define bufferAdd(byte) \ |
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if ( KeyIndex_BufferUsed < KEYBOARD_BUFFER ) \ |
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KeyIndex_Buffer[KeyIndex_BufferUsed++] = byte |
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// ----- Variables ----- |
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// Buffer used to inform the macro processing module which keys have been detected as pressed |
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volatile uint8_t KeyIndex_Buffer[KEYBOARD_BUFFER]; |
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volatile uint8_t KeyIndex_BufferUsed; |
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// ----- Function Declarations ----- |
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void processPacketValue( uint16_t packetValue ); |
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// ----- Interrupt Functions ----- |
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// XXX - None Required |
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// ----- Functions ----- |
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// Setup |
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// This setup is very simple, as there is no extra hardware used in this scan module, other than GPIOs. |
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// To be nice, we wait a little bit after powering on, and dump any of the pending keyboard data. |
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// Afterwards (as long as no keys were being held), the keyboard should have a clean buffer, and be ready to go. |
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// (Even if keys were held down, everything should probably still work...) |
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inline void scan_setup() |
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{ |
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// Setup the DATA pin |
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DATA_DDR &= ~(1 << DATA_PIN); // Set to input |
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DATA_PORT |= (1 << DATA_PIN); // Set to pull-up resistor |
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// Setup the REQUEST pin |
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REQUEST_DDR |= (1 << REQUEST_PIN); // Set to output |
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STOP_DATA(); // Set the line high to stop incoming data |
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// Reset the keyboard before scanning, we might be in a wierd state |
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_delay_ms( 50 ); |
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scan_resetKeyboard(); |
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} |
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// Main Detection Loop |
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// The Univac-Sperry F3W9 has a convenient feature, an internal 8 key buffer |
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// This buffer is only emptied (i.e. sent over the bus) when the REQUEST line is held high |
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// Because of this, we can utilize the scan_loop to do all of the critical processing, |
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// without having to resort to interrupts, giving the data reading 100% of the CPU. |
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// This is because the USB interrupts can wait until the scan_loop is finished to continue. |
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// |
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// Normally, this approach isn't taken, as it's easier/faster/safer to use Teensy hardware shift registers |
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// for serial data transfers. |
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// However, since the Univac-Sperry F3W9 sends 20 bit packets (including the start bit), the Teensy |
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// doesn't have a shift register large enough (9 bit max), to hold the data. |
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// So the line must be polled manually using CPU cycles |
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// |
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// Another interesting feature is that there are 2 data lines. |
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// Output and /Output (NOT'ted version). |
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// Not really useful here, but could be used for error checking, or eliminating an external NOT gate if |
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// we were using (but can't...) a hardware decoder like a USART. |
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inline uint8_t scan_loop() |
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{ |
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// Protocol Notes: |
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// - Packets are 20 bits long, including the start bit |
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// - Each bit is ~105 usecs in length |
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// - Thus the average packet length is 2.205 msecs |
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// - Each packet is separated by at least 240 usecs (during a buffer unload) |
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// - While holding the key down, each packet has a space of about 910 usecs |
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// - A max of 8 keys can be sent at once (note, the arrow keys seem use 2 packets each, and thus take up twice as much buffer) |
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// - There is no timing danger for holding the request line, just that data may come in when you don't want it |
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// Now that the scan loop has been entered, we don't have to worry about interrupts stealing |
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// precious cycles. |
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REQUEST_DATA(); |
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// = Delays = |
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// |
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// For these calculations to work out properly, then Teensy should be running at 16 MHz |
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// - 1 bit : 105 usecs is 16 000 000 * 0.000105 = 1680 instructions |
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// - Bit centering : 52.5 usecs is 16 000 000 * 0.0000525 = 840 instructions |
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// - Delay : 5 msecs is 16 000 000 * 0.005 = 80 000 instructions |
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// - Microsecond : 1 usec is 16 000 000 * 0.000001 = 16 instructions |
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// |
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// Now, either I can follow these exactly, or based upon the fact that I have >840 tries to find the |
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// the start bit, and >1680 tries to read the subsequent bits, I have some "flex" time. |
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// Knowing this, I can make some assumptions that because I'm only reading a total of 20 bits, and will |
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// be re-centering for each packet. |
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// This will allow for less worrying about compiler optimizations (and porting!). |
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// The basic idea is to find a "reliable" value for the start bit, e.g. read it ~10 times. |
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// Using a for-loop and some addition counters, this should eat up approximately 20-30 instructions per read |
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// (very loose estimation). |
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// So reading 10 * 30 instructions = 300 instructions, which is much less than 840 instructions to where the |
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// bit center is, but is close enough that further delays of ~>1680 instructions will put the next read |
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// within the next bit period. |
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// This is all possible because interrupts are disabled at this point, otherwise, all of this reasoning |
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// would fall apart. |
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// _delay_us is available to use, fortunately. |
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// Input Packet Storage (before being processed) |
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uint16_t incomingPacket[PACKET_STORAGE]; |
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uint8_t numberOfIncomingPackets = 0; |
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// Sample the data line for ~5 ms, looking for a start bit |
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// - Sampling every 1 usecs, looking for 10 good samples |
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// - Accumulated samples will dumped if a high is detected |
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uint8_t samples = 0; |
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uint16_t failures = 0; |
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// Continue waiting for a start bit until MAX_FAILURES has been reached (~5ms of nothing) |
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while ( failures <= MAX_FAILURES ) |
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{ |
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// Attempt to find the start bit |
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while ( samples < MAX_SAMPLES ) |
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{ |
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// Delay first |
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_delay_us( 1 ); |
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// If data is valid, increment |
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if ( READ_DATA ) |
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{ |
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samples++; |
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} |
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// Reset |
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else |
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{ |
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samples = 0; |
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failures++; |
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// After ~5ms of failures, break the loop |
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// Each failure is approx 5 instructions + 1 usec, or approximately 1.34 usec) |
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// So ~3731 failures for ~5ms |
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// Being exact doesn't matter, as this is just to let the other parts of the |
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// controller do some processing |
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if ( failures > MAX_FAILURES ) |
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break; |
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} |
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} |
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// If 10 valid samples of the start bit were obtained, |
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if ( samples >= MAX_SAMPLES ) |
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{ |
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// Clean out the old packet memory |
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incomingPacket[numberOfIncomingPackets] = 0; |
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// Read the next 19 bits into memory (bit 0 is the start bit, which is always 0) |
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for ( uint8_t c = 1; c < 20; c++ ) |
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{ |
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// Wait until the middle of the next bit |
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_delay_us( 105 ); |
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// Append the current bit value |
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incomingPacket[numberOfIncomingPackets] |= (READ_DATA << c); |
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} |
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// Packet finished, increment counter |
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numberOfIncomingPackets++; |
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} |
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} |
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// Stop the keyboard input |
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STOP_DATA(); |
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// Finished receiving data from keyboard, start packet processing |
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for ( uint8_t packet = 0; packet < numberOfIncomingPackets; packet++ ) |
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processPacketValue( incomingPacket[packet] ); |
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return 0; |
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} |
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// Read in the Packet Data, and decide what to do with it |
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void processPacketValue( uint16_t packetValue ) |
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{ |
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// = Packet Layout = |
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// |
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// A is the first bit received (bit 0), T is the last |
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// |
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// | Modifier? | ?? | Scan Code | |
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// A B C D E F G H I J K L M N O P Q R S T |
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// |
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// A - Start bit |
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// - Always Low |
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// B -> H - Modifier enabled bits |
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// - Each bit represents a different modifier "mode" |
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// - B -> Shift/Lock |
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// - C -> ?? |
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// - D -> Func |
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// - E -> ?? |
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// - F -> ?? |
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// - G -> ?? |
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// - H -> ?? |
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// I -> L - ?? No idea yet... |
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// - The bits change for some combinations, but not pattern has been found yet... |
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// - I -> ?? |
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// - J -> ?? |
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// - K -> ?? |
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// - L -> ?? |
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// M -> T - Scan Code |
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// - Bits are organized from low to high (8 bit value) |
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// - M -> Bit 1 |
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// - N -> Bit 2 |
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// - O -> Bit 3 |
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// - P -> Bit 4 |
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// - Q -> Bit 5 |
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// - R -> Bit 6 |
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// - S -> Bit 7 |
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// - T -> Bit 8 |
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// Separate packet into sections |
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uint8_t scanCode = (packetValue & 0xFF000) << 12; |
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uint8_t modifiers = (packetValue & 0x000FE); |
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uint8_t extra = (packetValue & 0x00F00) << 8; |
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// Debug Info |
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char tmpStr1[3]; |
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char tmpStr2[3]; |
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char tmpStr3[3]; |
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hexToStr_op( scanCode, tmpStr1, 2 ); |
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hexToStr_op( modifiers, tmpStr2, 2 ); |
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hexToStr_op( extra, tmpStr3, 2 ); |
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dbug_dPrint( "Scancode: 0x", tmpStr1, " Modifiers: 0x", tmpStr2, " Extra: 0x", tmpStr3 ); |
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dbug_dPrint( "Packet: 0x", tmpStr2, tmpStr3, tmpStr1 ); |
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// TODO List |
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// - Modifier keys |
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// - Key Release mechanism |
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// Compute Modifier keys |
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// TODO |
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// Deal with special scan codes |
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switch ( scanCode ) |
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{ |
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default: |
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//bufferAdd( scanCode ); TODO - Uncomment when ready for USB output |
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break; |
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} |
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} |
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// Send data |
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// NOTE: Does nothing with the Univac-Sperry F3W9 |
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uint8_t scan_sendData( uint8_t dataPayload ) |
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{ |
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return 0; |
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} |
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// Signal KeyIndex_Buffer that it has been properly read |
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inline void scan_finishedWithBuffer( void ) |
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{ |
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return; |
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} |
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// Signal that the keys have been properly sent over USB |
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// TODO |
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inline void scan_finishedWithUSBBuffer( void ) |
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{ |
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/* |
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uint8_t foundModifiers = 0; |
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// Look for all of the modifiers present, there is a max of 8 (but only keys for 5 on the HASCI version) |
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for ( uint8_t c = 0; c < KeyIndex_BufferUsed; c++ ) |
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{ |
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// The modifier range is from 0x80 to 0x8F (well, the last bit is the ON/OFF signal, but whatever...) |
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if ( KeyIndex_Buffer[c] <= 0x8F && KeyIndex_Buffer[c] >= 0x80 ) |
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{ |
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// Add the modifier back into the the Key Buffer |
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KeyIndex_Buffer[foundModifiers] = KeyIndex_Buffer[c]; |
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foundModifiers++; |
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} |
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} |
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// Adjust the size of the new Key Buffer |
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KeyIndex_BufferUsed = foundModifiers; |
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*/ |
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} |
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// Reset/Hold keyboard |
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// NOTE: Does nothing with the Univac-Sperry F3W9 |
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void scan_lockKeyboard( void ) |
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{ |
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} |
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// NOTE: Does nothing with the Univac-Sperry F3W9 |
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void scan_unlockKeyboard( void ) |
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{ |
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} |
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// Reset Keyboard |
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// - Holds the input read line high to flush the buffer |
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// - This does not actually reset the keyboard, but always seems brings it to a sane state |
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// - Won't work fully if keys are being pressed done at the same time |
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void scan_resetKeyboard( void ) |
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{ |
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// Initiate data request line, but don't read the incoming data |
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REQUEST_DATA(); |
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// We shouldn't be receiving more than 8 packets (and maybe +1 error signal) |
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// This is around 22 ms of data, so a delay of 50 ms should be sufficient. |
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_delay_ms( 50 ); |
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// Stop request line |
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STOP_DATA(); |
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} |
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