89 lines
4.4 KiB
C++
89 lines
4.4 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 implements an I2C Touchpad Controller using a Teensy 3.2
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// It assumes the TP is at I2C address 0x24
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// Register 0 is the pointer register used to access all other registers
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// Register 1 is the button register. 0x00=no buttons, 0x03=left button, 0x04=right button
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// Register 2 function unknown - not used
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// Register 3 is the X delta movement 8 bit 2's complement value. Left to right gives positive values
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// Register 4 is the Y delta movement 8 bit 2's complement value. Top to bottom gives positive values
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// Register 5 function unknown - not used
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// Register 6 is the touch sensor. 0x00=no touch, 0x0f=touch - The code below does not use this register
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//
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// Release Date: August 3, 2021
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//
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#include <Wire.h> // used for i2c bus to touchpad
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//
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// define the pins on the Teensy used for the touchpad I2C bus
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#define TP_DATA 14 // Touchpad i2c data signal
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#define TP_CLK 15 // Touchpad i2c clock signal
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//
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//----------------------------------Setup before main loop-------------------------------------------
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//
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void setup() {
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Wire.begin(); // i2c for touchpad
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}
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// declare and initialize touchpad variables
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char buttonreg; // touchpad left and right buttons read from register #1. Left button is bit 0 and 1, right button is bit 2
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char xreg; // touchpad x movement from register #3. 2's complement, left to right movement gives positive value.
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char yreg; // touchpad y movement from register #4. 2's complement, top to bottom movement gives positive value.
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boolean left_button = 0; // Active high, on/off variable for left button
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boolean right_button = 0; // Active high, on/off variable for right button
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boolean old_left_button = 0; // Active high, on/off variable for left button status from the previous polling cycle
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boolean old_right_button = 0; // Active high, on/off variable for right button status from the previous polling cycle
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boolean button_change = 0; // Active high, shows when a touchpad left or right button has changed since the last polling cycle
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//
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//---------------------------------Main Loop---------------------------------------------
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//
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void loop() {
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// poll the touchpad for new movement or button data
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//
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Wire.beginTransmission(0x24); // Load the TP register pointer
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Wire.write(0x01); // so it points to register 1
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Wire.endTransmission(); //
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Wire.requestFrom(0x24, 4); // Read 4 bytes from the TP starting at register 1
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buttonreg = Wire.read(); // read the button status bits in register 1
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Wire.read(); // read and throw away byte from unused register 2
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xreg = Wire.read(); // read the X value from register 3
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yreg = Wire.read(); // read the Y value from register 4
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// send the x and y data back via usb if either one is non-zero
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if ((xreg != 0x00) || (yreg != 0x00)) {
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Mouse.move(xreg,yreg);
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}
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//
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// check the left and right bits in the button register from the touchpad
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if (buttonreg == 0x03) { // the left button is pushed
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left_button = 1; // set the left button variable
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}
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else { // otherwise clear the left button variable
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left_button = 0;
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}
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if (buttonreg == 0x04) { // the right button is pushed
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right_button = 1; // set the right button variable
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}
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else { // otherwise clear right button variable
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right_button = 0;
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}
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// Determine if the left or right touchpad buttons have changed since last polling cycle using xor
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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 left, middle, and right button status
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}
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old_left_button = left_button; // remember button status for next polling cycle
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old_right_button = right_button;
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//
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delay(25); // This is the polling rate in msec
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//
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}
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