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ls_sensor.ino
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ls_sensor.ino
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/******************************** ls_sensor: LinnStrument Sensor **********************************
This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License.
To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/
or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.
***************************************************************************************************
These functions handle the sensing of touches on the LinnStrument's touch surface.
**************************************************************************************************/
// These are the rectified pressure sensititivies for each column
// CAREFUL, contrary to all the other arrays these are rows first and columns second since it makes it much easier to visualize and edit the
// actual values in a spreadsheet
short Z_BIAS[MAXROWS][MAXCOLS];
const short Z_BIAS_200_SEPTEMBER2014[MAXROWS][MAXCOLS] = {
{350, 1506, 1497, 1417, 1357, 1297, 1241, 1205, 1177, 1153, 1129, 1109, 1093, 1087, 1087, 1089, 1095, 1093, 1109, 1121, 1157, 1209, 1277, 1361, 1441, 1256},
{350, 1506, 1418, 1350, 1282, 1222, 1178, 1150, 1126, 1101, 1086, 1070, 1062, 1054, 1050, 1050, 1054, 1062, 1074, 1086, 1114, 1150, 1214, 1290, 1386, 1256},
{350, 1443, 1359, 1295, 1227, 1175, 1143, 1119, 1095, 1067, 1051, 1039, 1031, 1019, 1016, 1018, 1023, 1029, 1039, 1051, 1079, 1111, 1171, 1243, 1331, 1193},
{350, 1400, 1320, 1260, 1200, 1152, 1120, 1096, 1072, 1048, 1036, 1024, 1016, 1006, 1000, 1000, 1006, 1012, 1020, 1032, 1056, 1088, 1150, 1216, 1293, 1150},
{350, 1400, 1320, 1260, 1200, 1152, 1120, 1096, 1072, 1048, 1036, 1024, 1016, 1006, 1000, 1000, 1006, 1012, 1020, 1032, 1056, 1088, 1150, 1216, 1293, 1150},
{350, 1443, 1359, 1295, 1227, 1175, 1143, 1119, 1095, 1067, 1051, 1039, 1031, 1019, 1016, 1018, 1023, 1029, 1039, 1051, 1079, 1111, 1171, 1243, 1331, 1193},
{350, 1506, 1418, 1350, 1282, 1222, 1178, 1150, 1126, 1101, 1086, 1070, 1062, 1054, 1050, 1050, 1054, 1062, 1074, 1086, 1114, 1150, 1214, 1290, 1386, 1256},
{350, 1506, 1497, 1417, 1357, 1297, 1241, 1205, 1177, 1153, 1129, 1109, 1093, 1087, 1087, 1089, 1095, 1093, 1109, 1121, 1157, 1209, 1277, 1361, 1441, 1256}
};
const short Z_BIAS_128_SEPTEMBER2016[MAXROWS][MAXCOLS] = {
{500, 2560, 2320, 2150, 2020, 1920, 1840, 1780, 1720, 1700, 1730, 1790, 1860, 1940, 2020, 2100, 2160, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{500, 2220, 2040, 1900, 1780, 1680, 1600, 1560, 1520, 1500, 1530, 1570, 1640, 1720, 1800, 1900, 2000, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{500, 2200, 1980, 1860, 1720, 1600, 1510, 1470, 1440, 1440, 1460, 1470, 1500, 1580, 1680, 1780, 1900, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{500, 2100, 1960, 1820, 1700, 1580, 1500, 1440, 1420, 1400, 1440, 1500, 1560, 1640, 1740, 1860, 2000, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{500, 1920, 1840, 1740, 1660, 1600, 1540, 1520, 1490, 1480, 1500, 1560, 1660, 1760, 1840, 1960, 2040, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{500, 2080, 1920, 1800, 1720, 1640, 1580, 1524, 1500, 1480, 1520, 1580, 1660, 1760, 1860, 1960, 2080, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{500, 2240, 2080, 1940, 1800, 1720, 1640, 1580, 1540, 1540, 1560, 1600, 1660, 1760, 1880, 2000, 2140, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{500, 2320, 2120, 1980, 1900, 1820, 1740, 1680, 1650, 1660, 1700, 1760, 1820, 1880, 1960, 2060, 2200, 0, 0, 0, 0, 0, 0, 0, 0, 0}
};
// Make LS128 feel more like LS200, here is the LS200 bias array but with the center 9 columns removed:
// delete from here ^ to here ^
const short Z_BIAS_128_SEPTEMBER2019[MAXROWS][MAXCOLS] = {
{350, 1506, 1497, 1417, 1357, 1297, 1241, 1205, 1177, 1109, 1121, 1157, 1209, 1277, 1361, 1441, 1256, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{350, 1506, 1418, 1350, 1282, 1222, 1178, 1150, 1126, 1074, 1086, 1114, 1150, 1214, 1290, 1386, 1256, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{350, 1443, 1359, 1295, 1227, 1175, 1143, 1119, 1095, 1039, 1051, 1079, 1111, 1171, 1243, 1331, 1193, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{350, 1400, 1320, 1260, 1200, 1152, 1120, 1096, 1072, 1020, 1032, 1056, 1088, 1150, 1216, 1293, 1150, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{350, 1400, 1320, 1260, 1200, 1152, 1120, 1096, 1072, 1020, 1032, 1056, 1088, 1150, 1216, 1293, 1150, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{350, 1443, 1359, 1295, 1227, 1175, 1143, 1119, 1095, 1039, 1051, 1079, 1111, 1171, 1243, 1331, 1193, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{350, 1506, 1418, 1350, 1282, 1222, 1178, 1150, 1126, 1074, 1086, 1114, 1150, 1214, 1290, 1386, 1256, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{350, 1506, 1497, 1417, 1357, 1297, 1241, 1205, 1177, 1109, 1121, 1157, 1209, 1277, 1361, 1441, 1256, 0, 0, 0, 0, 0, 0, 0, 0, 0}
};
const short Z_BIAS_MULTIPLIER = 1400;
// readX:
// Reads raw X value at the currently addressed column and row
const short READX_FLATZONE = 25;
const short READX_RANGE = 25;
const short READX_MAX_DELAY = 250;
const short READX_MIN_DELAY = 150;
const short READX_RANGE_DELAY = READX_MAX_DELAY - READX_MIN_DELAY;
void initializeSensors() {
if (LINNMODEL == 200) {
for (byte r = 0; r < MAXROWS; ++r) {
for (byte c = 0; c < MAXCOLS; ++c) {
Z_BIAS[r][c] = Z_BIAS_200_SEPTEMBER2014[r][c];
}
}
}
else if (LINNMODEL == 128) {
for (byte r = 0; r < MAXROWS; ++r) {
for (byte c = 0; c < MAXCOLS; ++c) {
Z_BIAS[r][c] = Z_BIAS_128_SEPTEMBER2019[r][c];
}
}
}
Device.sensorSensitivityZ = DEFAULT_SENSOR_SENSITIVITY_Z;
Device.sensorLoZ = DEFAULT_SENSOR_LO_Z;
Device.sensorFeatherZ = DEFAULT_SENSOR_FEATHER_Z;
Device.sensorRangeZ = DEFAULT_SENSOR_RANGE_Z;
}
inline short readX(byte zPct) { // returns the raw X value at the addressed cell
#ifdef TESTING_SENSOR_DISABLE
if (sensorCell->disabled) {
return 0;
}
#endif
DEBUGPRINT((3,"readX\n"));
selectSensorCell(sensorCol, sensorRow, READ_X); // set analog switches to this column and row, and to read X
short d;
if (zPct <= READX_FLATZONE) {
d = READX_MAX_DELAY;
}
else {
d = READX_MAX_DELAY - (READX_RANGE_DELAY * min(zPct - READX_FLATZONE, READX_RANGE) / READX_RANGE);
}
delayUsec(d); // delay required after setting analog switches for stable X read
return spiAnalogRead();
}
// readY:
// Reads Y value for current cell and returns a value of 0-127 within cell's y axis
const short READY_FLATZONE = 30;
const short READY_RANGE = 40;
const short READY_MAX_DELAY = 200;
const short READY_MIN_DELAY = 60;
const short READY_RANGE_DELAY = READY_MAX_DELAY - READY_MIN_DELAY;
inline short readY(byte zPct) { // returns a value of 0-127 within cell's y axis
#ifdef TESTING_SENSOR_DISABLE
if (sensorCell->disabled) {
return 0;
}
#endif
DEBUGPRINT((3,"readY\n"));
selectSensorCell(sensorCol, sensorRow, READ_Y); // set analog switches to this cell and to read Y
short d;
if (zPct <= READY_FLATZONE) {
d = READY_MAX_DELAY;
}
else {
d = READY_MAX_DELAY - (READY_RANGE_DELAY * min(zPct - READY_FLATZONE, READY_RANGE) / READY_RANGE);
}
delayUsec(d); // delay required after setting analog switches for stable Y read
return spiAnalogRead();
}
// readZ:
// Reads Z value at current cell
const short READZ_DELAY_CONTROLMODE = 50;
const short READZ_DELAY_SWITCH = 24;
const short READZ_DELAY_SENSOR = 15;
const short READZ_DELAY_SENSORINITIAL = 14;
const short READZ_SETTLING_PRESSURE_THRESHOLD = 80;
inline short applyRawZBias(short rawZ) {
// apply the bias for each column, we also raise the baseline values to make the highest points just as sensitive and the lowest ones more sensitive
return rawZ = (rawZ * Z_BIAS_MULTIPLIER) / Z_BIAS[sensorRow][sensorCol];
}
inline unsigned short readZ() { // returns the raw Z value
#ifdef TESTING_SENSOR_DISABLE
if (sensorCell->disabled) {
return 0;
}
#endif
DEBUGPRINT((3,"readZ\n"));
selectSensorCell(sensorCol, sensorRow, READ_Z); // set analog switches to current cell in touch sensor and read Z
short rawZ;
if (controlModeActive) {
delayUsec(READZ_DELAY_CONTROLMODE);
// read raw Z value and invert it from (4095 - 0) to (0-4095)
rawZ = 4095 - spiAnalogRead();
}
else {
// if there are active touches in the column, always use a settling time
if (sensorCol == 0) {
delayUsec(READZ_DELAY_SWITCH);
}
else if (rowsInColsTouched[sensorCol]) {
delayUsec(READZ_DELAY_SENSOR);
}
// read raw Z value and invert it from (4095 - 0) to (0-4095)
rawZ = 4095 - spiAnalogRead();
// if there are no active touches in the column, but the raw pressure without settling time exceeds the value threshold,
// introduce a settling time to read the proper stabilized value
if (rowsInColsTouched[sensorCol] == 0 && rawZ > READZ_SETTLING_PRESSURE_THRESHOLD) {
delayUsec(READZ_DELAY_SENSORINITIAL);
rawZ = 4095 - spiAnalogRead();
}
}
// store the last value that was read straight off of the sensor without any compensation
lastReadSensorRawZ = rawZ;
// scale the sensor based on the sensitivity setting
rawZ = rawZ * Device.sensorSensitivityZ / 100;
rawZ = applyRawZBias(rawZ);
return rawZ;
}
// spiAnalogRead:
// returns raw ADC output at current cell
inline short spiAnalogRead() {
byte msb = SPI.transfer(SPI_ADC, 0, SPI_CONTINUE); // read byte MSB
byte lsb = SPI.transfer(SPI_ADC, 0); // read byte LSB
// assemble the 2 transfered bytes into an int
short raw = short(msb) << 8;
raw |= lsb;
// shift the 14-bit value from bits 16-2 to bits 14-0
return (raw >> 2) & 0xFFF;
}
/****************************************************** ANALOG SWITCHES *********************************************/
/*
selectSensorCell:
Sends a 16-bit word over SPI to the touch sensor in order to set the analog switches to:
1) select a column and row, and
2) connect ends of rows and columns to various combination of 3.3 volts, ground and ADC (with or without pullup) in order to read X, Y or Z.
Here are what each of the bits do:
MS byte:
7 6 5 4 3 2 1 0
colBotSw ColTopSw colAdr4inv colAdr4 colAdr3 colAdr2 colAdr1 colAdr0
0=gnd, 1=ADC 0=ADC, 1=+3.3v
if switchCode = READ_X: 1 0 colAdr4inv colAdr4 colAdr3 colAdr2 colAdr1 colAdr0
if switchCode = READ_Y: 0 1 colAdr4inv colAdr4 colAdr3 colAdr2 colAdr1 colAdr0
if switchCode = READ_Z: 1 0 colAdr4inv colAdr4 colAdr3 colAdr2 colAdr1 colAdr0
LS byte:
7 6 5 4 3 2 1 0
not used rowRightSwB adcPullup rowRightSwA rowLeftSw rowAdr2 rowAdr1 rowAdr0
0=ADC,1=+3.3 1=pullup,0=not 0=gnd,1=RT_SW_B 0=gnd, 1=ADC
if switchCode = READ_X: 1 0 1 0 rowAdr2 rowAdr1 rowAdr0
if switchCode = READ_Y: 0 0 1 1 rowAdr2 rowAdr1 rowAdr0
if switchCode = READ_Z: N/A 1 0 0 rowAdr2 rowAdr1 rowAdr0
*/
// col: column to be addressed by analog switches
// row: row to be addressed by analog switches
// switchCode: set analog switches to read X (0), Y (1) or Z (2)
inline void selectSensorCell(byte col, byte row, byte switchCode) {
// first set lower 5 bits of MSB to specified column
byte msb = col; // set MSB of SPI value to column
if ((col & 16) == 0) msb = col | B00100000; // if column address 4 is 0, set bit 5 of MSB (inverted state of bit 4) to 1
// then set lower 3 bits of LSB to specified row
byte lsb = row; // set LSB of SPI value to row
// now, set bits 5-7 of MSB and bits 3-6 of LSB (routing analog swiches)
switch (switchCode) // set SPI values differently depending on reading X, Y or Z
{
case READ_X: // if reading X...
msb |= B10000000; // set colBotSw to ADC
lsb |= B01010000; // set rowRightSwA to RT_SW_B and rowRightSwB to +3.3 (for low-R Analog Devices switches)
break;
case READ_Y: // if reading Y...
msb |= B01000000; // set colTopSw to +3.3v
lsb |= B00011000; // set rowRightSwA to RT_SW_B and rowRightSwB to ADC (for low-R Analog Devices switches)
break;
case READ_Z: // if reading Z...
msb |= B10000000; // set colBotSw to ADC
lsb |= B00100000; // set rowRightSwA to GND and rowRightSwB doesn't matter (for low-R Analog Devices switches)
break;
default:
break;
}
SPI.transfer(SPI_SENSOR, lsb, SPI_CONTINUE); // to daisy-chained 595 (LSB)
SPI.transfer(SPI_SENSOR, msb); // to first 595 at MOSI (MSB, for both sensor columns and LED columns)
}