8 years ago · d177dbfa97
--- a/src/Row.cpp
+++ b/src/Row.cpp
 Larger SAMPLE_COUNTs are more reliable but consume more memory, where
 SAMPLE_COUNT*ROW_COUNT = bytes of memory consumed by keyboard
 SAMPLE_COUNT = 4 is very reliable for a keyboard.
 Avoid sampling the switch input at a rate synchronous to events in the environment
 that might create periodic EMI. For instance, 50 and 60 Hz.
 A keyboard with a faster scan rate responds faster.
 Follow these step to tune DELAY_MICROSECONDS for maximum scan rate for a given SAMPLE_COUNT:
 Initialize DELAY_MICROSECONDS in your sketch:
 const unsigned int Row::DELAY_MICROSECONDS = 1000;
 Add this to the sketch's loop() function:
 debug.print_microseconds_per_scan();
 Compile and load the sketch into the microcontroller; microseconds_per_scan is printed every second.
 Adjust the value of DELAY_MICROSECONDS and repeat until:
 debug.print_microseconds_per_scan() <= DEBOUNCE_TIME / SAMPLE_COUNT
 DEBOUNCE_TIME can be obtained from the switch's datasheet. Some switch bounce times are:
 Cherry MX specifies 5msec bounce time http://www.cherrycorp.com/english/switches/key/mx.htm
 hasu measured Cherry MX bounce times .3ms to 1.4ms http://geekhack.org/index.php?topic=42385.0
 Tactile switch MJTP series bounce 10 ms http://www.apem.com/files/apem/brochures/MJTP_6MM.pdf 
 Polling I2C may slow the scan rate enough so that no additional delay is needed:
 const unsigned int Row::DELAY_MICROSECONDS = 0;
 Slow-scan trick for debug messages that print too fast:
 change DELAY_MICROSECONDS to a large number like 10000
 That way debug messages are printed at a managable rate.
 */
 /* debounce() function
 Parameter rowState is bitwise, 1 means pressed, 0 means released.
--- a/src/Row.h
+++ b/src/Row.h
 class Row : public RowBase
 {
 private:
 static const unsigned int DELAY_MICROSECONDS; //delay between each Row scan for debouncing
 uint8_t samples[SAMPLE_COUNT]; //bitwise, one bit per key, most recent readings
 uint8_t samplesIndex; //samples[] current write index
 virtual uint8_t debounce(const uint8_t rowState);
--- a/src/RowBase.cpp
+++ b/src/RowBase.cpp
 uint16_t rowEnd; //1 bit marks positioned after last key of row 
 uint8_t debouncedChanged; //1 means debounced changed 
 wait(); 
 scan(activeHigh); //save column-port-pin values to portState 
 rowState = getRowState(rowEnd, activeHigh); 
 debouncedChanged = debounce(rowState); 
 pressRelease(rowEnd, debouncedChanged); 
 } 
 /* wait() delay's scan to give switches time to debounce. 
 This version of wait() is very simple. More sophisticated versions can override this one. 
 For fastest response time, wait() should be placed before scan() or after pressRelease() 
 (waiting between strobe and send would unnecessarily delay send). 
 A keyboard with a faster scan rate responds faster. 
 Follow these step to tune DELAY_MICROSECONDS for maximum scan rate for a given SAMPLE_COUNT: 
 Initialize DELAY_MICROSECONDS in your sketch: 
 const unsigned int Row::DELAY_MICROSECONDS = 1000; 
 Add this to the sketch's loop() function: 
 debug.print_microseconds_per_scan(); 
 Compile and load the sketch into the microcontroller; microseconds_per_scan is printed every second. 
 Adjust the value of DELAY_MICROSECONDS and repeat until: 
 debug.print_microseconds_per_scan() <= DEBOUNCE_TIME / SAMPLE_COUNT 
 DEBOUNCE_TIME can be obtained from the switch's datasheet. Some switch bounce times are: 
 Cherry MX specifies 5msec bounce time http://www.cherrycorp.com/english/switches/key/mx.htm 
 hasu measured Cherry MX bounce times .3ms to 1.4ms http://geekhack.org/index.php?topic=42385.0 
 Tactile switch MJTP series bounce 10 ms http://www.apem.com/files/apem/brochures/MJTP_6MM.pdf 
 Avoid sampling the switch input at a rate synchronous to events in the environment 
 that might create periodic EMI. For instance, 50 and 60 Hz. 
 Polling I2C may slow the scan rate enough so that no additional delay is needed: 
 const unsigned int Row::DELAY_MICROSECONDS = 0; 
 Slow-scan trick for debug messages that print too fast: 
 change DELAY_MICROSECONDS to a large number like 10000 
 That way debug messages are printed at a managable rate. 
 */ 
 void RowBase::wait() 
 { 
 delayMicroseconds(DELAY_MICROSECONDS); //delay between Row scans to debounce switches 
--- a/src/RowBase.h
+++ b/src/RowBase.h
 class RowBase 
 { 
 private: 
 static const unsigned int DELAY_MICROSECONDS; //delay between each Row scan for debouncing 
 Key *const *const ptrsKeys; //array of Key pointers 
 RowPort &refRowPort; //this row's IC port 
 ColPort *const *const ptrsColPorts; //array of column ports 
 const uint8_t colPortCount; 
 void wait(); 
 void scan(const bool activeHigh); 
 uint8_t getRowState(uint16_t& rowEnd, const bool activeHigh); 
 virtual uint8_t debounce(const uint8_t rowState)=0;