From fd6035e05336fe9626d7ab1eb755bb156b9e17f3 Mon Sep 17 00:00:00 2001 From: Jacob Alexander Date: Mon, 19 Nov 2012 00:55:30 -0800 Subject: [PATCH] Adding more robust detection for the HP150 - 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 --- Scan/HP150/scan_loop.c | 116 +++++++++++++++++++++++++++-------------- 1 file changed, 77 insertions(+), 39 deletions(-) diff --git a/Scan/HP150/scan_loop.c b/Scan/HP150/scan_loop.c index be17cab..bfa0424 100644 --- a/Scan/HP150/scan_loop.c +++ b/Scan/HP150/scan_loop.c @@ -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 < 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; } }