165 lines
7.4 KiB
C++
165 lines
7.4 KiB
C++
/* Copyright 2021 Frank Adams
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// This software interfaces the Teensy 3.2 with a Fujitsu Ergotrac touch sensor from a Lifebook 755x.
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// Connections: Teensy I/O 9 to pin 1 - This drives the reference pulse to the touch sensor
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// Teensy ADC 10 to pin 2 - ADC reads this pulse voltage for the X movement
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// Teensy ADC 11 to pin 3 - ADC reads this pulse voltage for the Y movement
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// Teensy Ground to pin 4
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//
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// Revision History
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// Rev New Nov 2, 2021 - Original Release
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//
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// X/Y outputs from ErgoTrac feed Teensy ADC channels
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#define ErgoTrac_X A10
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#define ErgoTrac_Y A11
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// Reference signal from Teensy into ErgoTrac
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#define ErgoTrac_Ref 9
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// left and right mouse buttons
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#define TP_LEFT 8
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#define TP_RIGHT 7
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//
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// declare and initialize ErgoTrac variables
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int x_read; // stores the reading from the X ADC
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int y_read; // same for the Y ADC
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char mx; // signed byte used by the Mouse.move function for x value. Positive value moves to the right
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char my; // positive y value moves down
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int x_delta; // signed 16 bit value gives x movement amount
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int y_delta; // y version.
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int x_center; //resting position of x sensor
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int y_center; //resting position of y sensor
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int noise_zone = 150; // dead zone around the center.
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char slowdown_left = 75; // factor to slow the curser movement down going left
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char slowdown_right = 60; // factor to slow the curser movement down going right
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char slowdown_up = 70; // factor to slow the curser movement down going up
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char slowdown_down = 75; // factor to slow the curser movement down going down
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boolean left_button = 0; // on/off variable for left button, 1 = pushed
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boolean right_button = 0; // on/off variable for right button, 1 = pushed
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boolean old_left_button = 0; // on/off variable for left button from the previous cycle
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boolean old_right_button = 0; // on/off variable for right button from the previous cycle
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boolean button_change = 0; // Shows when the left or right buttons have changed, 1 = change
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// Function to set a pin to high impedance (acts like open drain output)
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void go_z(int pin)
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{
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pinMode(pin, INPUT);
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digitalWrite(pin, HIGH);
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}
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//
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// Function to set a pin as an input with a pullup
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void go_pu(int pin)
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{
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pinMode(pin, INPUT_PULLUP);
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digitalWrite(pin, HIGH);
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}
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//
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// Function to send a pin to a logic low
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void go_0(int pin)
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{
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pinMode(pin, OUTPUT);
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digitalWrite(pin, LOW);
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}
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//
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// Function to send a pin to a logic high
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void go_1(int pin)
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{
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pinMode(pin, OUTPUT);
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digitalWrite(pin, HIGH);
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}
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//
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// Function to re-capture the at-rest X & Y ADC values
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void recenter(void) {
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digitalWrite(ErgoTrac_Ref, LOW); // resting state of reference
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delay(25); // wait before sending calibration pulse
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digitalWrite(ErgoTrac_Ref, HIGH); // Send calibration pulse high
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delayMicroseconds(400); // wait before reading ADC to allow for rise time
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x_center = analogRead(ErgoTrac_X); // store the center (no movement) value for x
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y_center = analogRead(ErgoTrac_Y); // same for y
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delayMicroseconds(50); // wait before releasing calibration pulse
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digitalWrite(ErgoTrac_Ref, LOW); // Send calibration pulse back to resting state
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}
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// ************************************Begin Routine*********************************************************
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void setup()
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{
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go_pu(TP_RIGHT); // set right button as input with a pullup
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go_pu(TP_LEFT); // set left button as input with a pullup
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delay(2000); // wait to let things settle out
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analogReadRes(13); // set ADC resolution to 13 bits (16 bit ADC but low 3 bits are random noise)
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analogReadAveraging(8); // ADC will take the average of multiple reads to filter noise.
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pinMode(ErgoTrac_Ref, OUTPUT); // define Teensy I/O that drives the refernce pulses to the ErgoTrac
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recenter(); // capture the at-rest X and Y position
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delay(25); // wait before entering main loop
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}
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//
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// ************************************Main Loop***************************************************************
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void loop() {
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digitalWrite(ErgoTrac_Ref, HIGH); // send calibration reference pulse
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mx = 0; // for each loop, start with zero and update only if movement detected
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my = 0; // same for y
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// Read the ADC's
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x_read = analogRead(ErgoTrac_X); // read the ADC tied to the X sensor
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y_read = analogRead(ErgoTrac_Y); // read the ADC tied to the Y sensor
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// Check if X or Y movement is beyond the dead zone
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if ((x_read > (x_center + noise_zone)) || (x_read < (x_center - noise_zone)) || (y_read > (y_center + noise_zone)) || (y_read < (y_center - noise_zone))) {
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// Only do the following if at least one reading is beyond the dead zone.
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// Figure out if the X value is to the right or the left of the center resting value
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if (x_read > x_center) { // is X ADC to the right of the resting position?
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x_delta = (x_read - x_center) / slowdown_right; // find out how far beyond center. Divide it to slow it down.
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mx = byte(x_delta); // convert signed 16 bit to signed 8 bit
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}
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else { // X ADC is equal or to the left of the resting position
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x_delta = ((x_center - x_read) / slowdown_left) * -1; // Answer should be negative so multiply by -1
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mx = byte(x_delta); // convert signed 16 bit to signed 8 bit
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}
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// Figure out if the Y value is above or below the center resting value
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if (y_read > y_center) { // is Y ADC above the resting position?
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y_delta = ((y_read - y_center) / slowdown_down) * -1; // up movement is negative for Mouse.move function
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my = byte(y_delta); // convert signed 16 bit to signed 8 bit
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}
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else { // Y ADC is equal or below the resting position
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y_delta = (y_center - y_read) / slowdown_up;
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my = byte(y_delta); // convert signed 16 bit to signed 8 bit
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}
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}
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// send the x and y data over usb if either one is not at center position
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if ((mx != 0x00) || (my != 0x00)) {
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Mouse.move(mx,my);
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}
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digitalWrite(ErgoTrac_Ref, LOW); // release calibration reference
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//
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// Read the right button
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//
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if (!digitalRead(TP_RIGHT)) { // check if right button is low (low = pushed)
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right_button = 1; // set the right button
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}
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else { // clear right button
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right_button = 0; // clear the right button
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}
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// Read the left button
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if (!digitalRead(TP_LEFT)) { // check if left button is low (low = pushed)
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left_button = 1; // set the left button
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}
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else { // clear left button
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left_button = 0; // clear the left button
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}
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//
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// Determine if the buttons have changed (using XOR) since the last cycle
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button_change = ((left_button ^ old_left_button) | (right_button ^ old_right_button));
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// Don't send button status if there's no change since last time
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if (button_change){
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Mouse.set_buttons(left_button,0, right_button); // send button status over USB
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}
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old_left_button = left_button; // remember button status for the next cycle
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old_right_button = right_button;
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delay(25); // wait before repeating
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}
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