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Adding more robust detection for the HP150

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- All spare cycles are used to get a more accurate data line sample (waaaay more than actually needed, but this helps against noise)
- Switched to a pre/release (add/remove) rather than an add->clear mechanism (or a buffer+debounce/add->clear)
- Note that a pull-down resistor is NEEDED on the data line
This commit is contained in:
Jacob Alexander 2012-11-19 00:55:30 -08:00
parent 59e443552c
commit fd6035e053
1 changed files with 77 additions and 39 deletions
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116
Scan/HP150/scan_loop.c
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@ -69,9 +69,12 @@ 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;
volatile uint8_t statePositionCounter = 0;
volatile uint16_t stateSamplesTotal = 0;
volatile uint16_t stateSamples = 0;
// Buffer Signals
volatile uint8_t BufferReadyToClear;
@ -94,7 +97,7 @@ ISR( TIMER1_COMPA_vect )
{
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
statePositionCounter = positionCounter;
positionCounter++; // Counts the number of falling edges, reset is done by the controlling section (reset, or main scan)
}
else
@ -124,7 +127,9 @@ inline void scan_setup()
OCR1AH = 0x03;
OCR1AL = 0x1F;
TIMSK1 = (1 << OCIE1A);
CLOCK_DDR = (1 << CLOCK_PIN);
CLOCK_DDR |= (1 << CLOCK_PIN); // Set the clock pin as an output
DATA_PORT |= (1 << DATA_PIN); // Pull-up resistor for input the data line
sei();
@ -144,25 +149,12 @@ inline void scan_setup()
// 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 )
// Only use as a valid signal
// Check if there was a position change
if ( positionCounter != statePositionCounter )
{
// 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 )
// At least 80% of the samples must be valid
if ( stateSamples * 100 / stateSamplesTotal >= 80 )
{
// Reset the scan counter, all the keys have been iterated over
// Ideally this should reset at 128, however
@ -174,25 +166,60 @@ inline uint8_t scan_loop()
if ( positionCounter >= 124 )
{
positionCounter = 0;
// Clear key buffer
KeyIndex_BufferUsed = 0;
}
// Key Press Detected
else
// - Skip 0x00 to 0x0B (11) for better jitter immunity (as there are no keys mapped to those scancodes)
else if ( positionCounter > 0x0B )
{
char tmp[15];
hexToStr( positionCounter, tmp );
dPrintStrsNL( "Key: ", tmp );
bufferAdd( positionCounter );
// Make sure there aren't any duplicate keys
uint8_t c;
for ( c = 0; c < KeyIndex_BufferUsed; c++ )
if ( KeyIndex_Buffer[c] == positionCounter )
break;
// No duplicate keys, add it to the buffer
if ( c == KeyIndex_BufferUsed )
bufferAdd( positionCounter );
}
}
// Remove the key from the buffer
else if ( positionCounter < 124 && positionCounter > 0x0B )
{
// Check for the released key, and shift the other keys lower on the buffer
uint8_t c;
for ( c = 0; c < KeyIndex_BufferUsed; c++ )
{
// Key to release found
if ( KeyIndex_Buffer[c] == positionCounter )
{
// Shift keys from c position
for ( uint8_t k = c; k < KeyIndex_BufferUsed - 1; k++ )
KeyIndex_Buffer[k] = KeyIndex_Buffer[k + 1];
// Decrement Buffer
KeyIndex_BufferUsed--;
break;
}
}
}
// Wait until the next falling clock edge for the next DATA scan
currentWaveDone++;
// Clear the state counters
stateSamples = 0;
stateSamplesTotal = 0;
statePositionCounter = positionCounter;
}
// Pull in a data sample for this read instance
if ( DATA_OUT & (1 <<DATA_PIN) )
stateSamples++;
stateSamplesTotal++;
// Check if the clock de-synchronized
// And reset
if ( positionCounter > 128 )
@ -205,6 +232,10 @@ inline uint8_t scan_loop()
positionCounter = 0;
KeyIndex_BufferUsed = 0;
// Clear the state counters
stateSamples = 0;
stateSamplesTotal = 0;
// A keyboard reset requires interrupts to be enabled
sei();
scan_resetKeyboard();
@ -257,22 +288,29 @@ void scan_resetKeyboard( void )
uint8_t synchronized = 0;
while ( !synchronized )
{
// Read on each falling edge/after the falling edge of the clock
if ( !currentWaveDone )
// Only use as a valid signal
// Check if there was a position change
if ( positionCounter != statePositionCounter )
{
// Read the current data value
if ( DATA_OUT & (1 << DATA_PIN) )
// At least 80% of the samples must be valid
if ( stateSamples * 100 / stateSamplesTotal >= 80 )
{
// Check if synchronized
// There are 128 positions to scan for with the HP150 keyboard protocol
if ( positionCounter == 128 )
synchronized = 1;
// 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;
positionCounter = 0;
}
}
// Wait until the next falling clock edge for the next DATA scan
currentWaveDone++;
// Clear the state counters
stateSamples = 0;
stateSamplesTotal = 0;
statePositionCounter = positionCounter;
}
}