127 lines
6 KiB
C++
127 lines
6 KiB
C++
/* Copyright 2020 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 Thinkpad 380ED laptop trackpoint.
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// The trackpoint strain gauge resistors are fed to an instrumentation amplifier which drives the
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// Teensy ADC inputs.
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// In the Arduino IDE, select Tools, Teensy 3.2. Also under Tools, select Keyboard+Mouse+Joystick
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//
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// Revision History
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// Rev 1.0 - April 22, 2020 - Original Release
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// Rev 1.1 - May 15, 2020 - Now using OSH Park PCB. Swapped A10 & A11. Added left & right mouse buttons.
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//
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// Defines
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#define TP_LEFT 20 // Trackpoint mouse buttons connected to Teensy 3.2 I/O's
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#define TP_RIGHT 5
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#define TP_RETURN 30
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// declare and initialize 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 = 50; // dead zone around the center. Can be as low as 3 but cursor may start to drift so add some safety margin.
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// Increase this number if the cursor moves without touching the TP. Decrease if too much force is needed.
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//
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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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//
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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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// 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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void setup()
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{
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delay(1000); // delay a second 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 8 reads to filter noise.
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x_center = analogRead(A11); // store the center (no movement) position for x
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y_center = analogRead(A10); // same for y
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//
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go_0(TP_RETURN); // send the buttons return pin low always
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go_pu(TP_RIGHT); // set right trackpoint button as input with a pullup
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go_pu(TP_LEFT); // set left trackpoint button as input with a pullup
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// When the keyboard code is added, detect when Fn - F8 is pushed to indicate that
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// x_center and y_center should be read again from the ADC. This would be because
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// the operator notices the cursor is moving without being pushed.
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}
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//
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// ************************************Main Loop***************************************************************
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void loop() {
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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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x_read = analogRead(A11); // read the ADC tied to the X sensor
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if (x_read > (x_center + noise_zone)) { // is ADC to the right of the noise zone beyond the resting position?
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x_delta = (x_read - (x_center + noise_zone)) / 10; // find out how far beyond noise zone. Divide by 10 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 if (x_read < (x_center - noise_zone)) { // is ADC to the left of the noise zone beyond the resting position?
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x_delta = (((x_center - noise_zone) - x_read) / 10) * -1; // Answer should be negative so multiply by -1
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mx = byte(x_delta);
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}
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y_read = analogRead(A10); // read the ADC tied to the Y sensor
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if (y_read > (y_center + noise_zone)) {
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y_delta = ((y_read - (y_center + noise_zone)) / 10) * -1; // up movement is negative for Mouse.move function
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my = byte(y_delta);
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}
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else if (y_read < (y_center - noise_zone)) {
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y_delta = (((y_center - noise_zone) - y_read) / 10);
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my = byte(y_delta);
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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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// ***********************read the touchpad left and right buttons***********************************
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if (!digitalRead(TP_RIGHT)) { // check if right button is low (low = pushed)
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right_button = 1; // save state of button
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}
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else { // clear right button
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right_button = 0; // save state of button
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}
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if (!digitalRead(TP_LEFT)) { // check if left button is low (low = pushed)
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left_button = 1; // save state of button
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}
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else { // clear left button
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left_button = 0; // save state of button
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}
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// Determine if the left or right mouse 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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//
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// **************************************End of trackpoint routine***********************************
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//
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delay(30); // wait 30ms before repeating next polling cycle
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}
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