USB_Laptop_Keyboard_Controller/Example_Touchpads/Touchpad_3p2.ino
2018-12-02 19:11:09 -08:00

377 lines
16 KiB
C++

/* Copyright 2018 Frank Adams
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// This software interfaces the Teensy 3.2 with a PS/2 touchpad found in an HP DV9000 laptop.
// The ps/2 code uses the USB PJRC Mouse functions at www.pjrc.com/teensy/td_mouse.html
// The ps/2 code has a watchdog timer so the code can't hang if a clock edge is missed.
// In the Arduino IDE, select Tools, Teensy LC. Also under Tools, select Keyboard+Mouse+Joystick
//
// Revision History
// Rev 1.0 - Nov 23, 2018 - Original Release
// Rev 1.1 - Dec 2, 2018 - Replaced ps/2 trackpoint code from playground arduino with my own code
//
// This code has been tested on the touchpad from an HP Pavilion DV9000
// Touchpad part number 920-000702-04 Rev A
// The test points on the touchpad were wired to a Teensy 3.2 as follows:
// T22 = 5V wired to the Teensy Vin pin
// T23 = Gnd wired to the Teensy Ground pin It's hard to solder to the T23 ground plane so I soldered to a bypass cap gnd pad.
// T10 = Clock wired to the Teensy I/O 30 pin
// T11 = Data wired to the Teensy I/O 27 pin
//
// Clock and Data measure open to the 5 volt pin, indicating no pull up resistors but,
// Clock and Data both measure 5 volts when the touchpad is powered, indicating active pullups are in
// the touchpad blob top chip.
// The ps/2 signals are at 5 volts from the touchpad to the Teensy which is 5 volt tolerant.
// The ps/2 signals are at 3.3 volts from the Teensy to the touchpad which is enough to be a logic high.
// In the Arduino IDE, select Tools, Teensy 3.2. Also under Tools, select Keyboard+Mouse+Joystick
//
// The touchpad ps/2 data and clock lines are connected to the following Teensy I/O pins
#define TP_DATA 27
#define TP_CLK 30
//
// Declare variable that will be used by functions
boolean touchpad_error = LOW; // sent high when touch pad routine times out
//
// Function to float a pin and let the pull-up or Touchpad determine the logic level
void go_z(int pin)
{
pinMode(pin, INPUT); // make the pin an input so it floats
digitalWrite(pin, HIGH);
}
// function to drive a pin to a logic low
void go_0(int pin)
{
pinMode(pin, OUTPUT);
digitalWrite(pin, LOW);
}
//
// *****************Functions for Touchpad***************************
//
// Function to send the touchpad a byte of data (command)
//
void tp_write(char send_data)
{
unsigned int timeout = 200; // breakout of loop if over this value in msec
elapsedMillis watchdog; // zero the watchdog timer clock
char odd_parity = 0; // clear parity bit count
// Enable the bus by floating the clock and data
go_z(TP_CLK); //
go_z(TP_DATA); //
delayMicroseconds(250); // wait before requesting the bus
go_0(TP_CLK); // Send the Clock line low to request to transmit data
delayMicroseconds(100); // wait for 100 microseconds per bus spec
go_0(TP_DATA); // Send the Data line low (the start bit)
delayMicroseconds(1); //
go_z(TP_CLK); // Release the Clock line so it is pulled high
delayMicroseconds(1); // give some time to let the clock line go high
while (digitalRead(TP_CLK) == HIGH) { // loop until the clock goes low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
// send the 8 bits of send_data
for (int j=0; j<8; j++) {
if (send_data & 1) { //check if lsb is set
go_z(TP_DATA); // send a 1 to TP
odd_parity = odd_parity + 1; // keep running total of 1's sent
}
else {
go_0(TP_DATA); // send a 0 to TP
}
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == LOW) { // loop until the clock goes high
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == HIGH) { // loop until the clock goes low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
send_data = send_data >> 1; // shift data right by 1 to prepare for next loop
}
// send the parity bit
if (odd_parity & 1) { //check if lsb of parity is set
go_0(TP_DATA); // already odd so send a 0 to TP
}
else {
go_z(TP_DATA); // send a 1 to TP to make parity odd
}
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == LOW) { // loop until the clock goes high
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == HIGH) { // loop until the clock goes low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
go_z(TP_DATA); // Release the Data line so it goes high as the stop bit
delayMicroseconds(80); // testing shows delay at least 40us
while (digitalRead(TP_CLK) == HIGH) { // loop until the clock goes low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
delayMicroseconds(1); // wait to let the data settle
if (digitalRead(TP_DATA)) { // Ack bit s/b low if good transfer
touchpad_error = HIGH; //bad ack bit so set the error flag
}
while ((digitalRead(TP_CLK) == LOW) || (digitalRead(TP_DATA) == LOW)) { // loop if clock or data are low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
// Inhibit the bus so the tp only talks when we're listening
go_0(TP_CLK);
}
//
// Function to get a byte of data from the touchpad
//
char tp_read(void)
{
unsigned int timeout = 200; // breakout of loop if over this value in msec
elapsedMillis watchdog; // zero the watchdog timer clock
char rcv_data = 0; // initialize to zero
char mask = 1; // shift a 1 across the 8 bits to select where to load the data
char rcv_parity = 0; // count the ones received
go_z(TP_CLK); // release the clock
go_z(TP_DATA); // release the data
delayMicroseconds(5); // delay to let clock go high
while (digitalRead(TP_CLK) == HIGH) { // loop until the clock goes low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
if (digitalRead(TP_DATA)) { // Start bit s/b low from tp
touchpad_error = HIGH; // No start bit so set the error flag
}
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == LOW) { // loop until the clock goes high
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
for (int k=0; k<8; k++) {
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == HIGH) { // loop until the clock goes low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
if (digitalRead(TP_DATA)) { // check if data is high
rcv_data = rcv_data | mask; // set the appropriate bit in the rcv data
rcv_parity++; // increment the parity bit counter
}
mask = mask << 1;
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == LOW) { // loop until the clock goes high
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
}
// receive parity
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == HIGH) { // loop until the clock goes low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
if (digitalRead(TP_DATA)) { // check if received parity is high
rcv_parity++; // increment the parity bit counter
}
rcv_parity = rcv_parity & 1; // mask off all bits except the lsb
if (rcv_parity == 0) { // check for bad (even) parity
touchpad_error = HIGH; //bad parity so set the error flag
}
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == LOW) { // loop until the clock goes high
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
// stop bit
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == HIGH) { // loop until the clock goes low
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
if (digitalRead(TP_DATA) == LOW) { // check if stop bit is bad (low)
touchpad_error = HIGH; //bad stop bit so set the error flag
}
delayMicroseconds(1); // delay to let the clock settle out
while (digitalRead(TP_CLK) == LOW) { // loop until the clock goes high
if (watchdog >= timeout) { //check for infinite loop
touchpad_error = HIGH; // set error flag
break; // break out of infinite loop
}
}
// Inhibit the bus so the tp only talks when we're listening
go_0(TP_CLK);
return rcv_data; // pass the received data back
}
//
void touchpad_init()
{
touchpad_error = LOW; // start with no error
go_z(TP_CLK); // float the clock and data to touchpad
go_z(TP_DATA);
// Sending reset command to touchpad
tp_write(0xff);
if (tp_read() != 0xfa) { // verify correct ack byte
touchpad_error = HIGH;
}
delayMicroseconds(100); // give the tp time to run its self diagnostic
// verify proper response from tp
if (tp_read() != 0xaa) { // verify basic assurance test passed
touchpad_error = HIGH;
}
if (tp_read() != 0x00) { // verify correct device id
touchpad_error = HIGH;
}
// increase resolution from 4 counts/mm to 8 counts/mm
tp_write(0xe8); // Sending resolution command
if (tp_read() != 0xfa) { // verify correct ack byte
touchpad_error = HIGH;
}
tp_write(0x03); // value of 03 = 8 counts/mm resolution (default is 4 counts/mm)
if (tp_read() != 0xfa) { // verify correct ack byte
touchpad_error = HIGH;
}
// Sending remote mode code so the touchpad will send data only when polled
tp_write(0xf0); // remote mode
if (tp_read() != 0xfa) { // verify correct ack byte
touchpad_error = HIGH;
}
if (touchpad_error == HIGH) { // check for any errors from tp
delayMicroseconds(300); // wait before trying to initialize tp one last time
tp_write(0xff); // send tp reset code
tp_read(); // read but don't look at response from tp
tp_read(); // read but don't look at response from tp
tp_read(); // read but don't look at response from tp
tp_write(0xe8); // Send resolution command
tp_read(); // read but don't look at response from tp
tp_write(0x03); // value of 03 gives 8 counts/mm resolution
tp_read(); // read but don't look at response from tp
tp_write(0xf0); // remote mode
tp_read(); // read but don't look at response from tp
delayMicroseconds(100);
}
}
// ************************************Begin Routine*********************************************************
void setup()
{
touchpad_init(); // reset touchpad, then set it's resolution and put it in remote mode
if (touchpad_error) {
touchpad_init(); // try one more time to initialize the touchpad
}
}
// declare and initialize variables
char mstat; // touchpad status reg = Y overflow, X overflow, Y sign bit, X sign bit, Always 1, Middle Btn, Right Btn, Left Btn
char mx; // touchpad x movement = 8 data bits. The sign bit is in the status register to
// make a 9 bit 2's complement value. Left to right on the touchpad gives a positive value.
char my; // touchpad y movement also 8 bits plus sign. Touchpad movement away from the user gives a positive value.
boolean over_flow; // set if x or y movement values are bad due to overflow
boolean left_button = 0; // on/off variable for left button = bit 0 of mstat
boolean right_button = 0; // on/off variable for right button = bit 1 of mstat
boolean old_left_button = 0; // on/off variable for left button status the previous polling cycle
boolean old_right_button = 0; // on/off variable for right button status the previous polling cycle
boolean button_change = 0; // Active high, shows when a touchpad left or right button has changed since last polling cycle
// ************************************Main Loop***************************************************************
void loop() {
// poll the touchpad for new movement data
over_flow = 0; // assume no overflow until status is received
touchpad_error = LOW; // start with no error
tp_write(0xeb); // request data
if (tp_read() != 0xfa) { // verify correct ack byte
touchpad_error = HIGH;
}
mstat = tp_read(); // save into status variable
mx = tp_read(); // save into x variable
my = tp_read(); // save into y variable
if (((0x80 & mstat) == 0x80) || ((0x40 & mstat) == 0x40)) { // x or y overflow bits set?
over_flow = 1; // set the overflow flag
}
// change the x data from 9 bit to 8 bit 2's complement
mx = mx >> 1; // convert to 7 bits of data by dividing by 2
mx = mx & 0x7f; // don't allow sign extension
if ((0x10 & mstat) == 0x10) { // move the sign into
mx = 0x80 | mx; // the 8th bit position
}
// change the y data from 9 bit to 8 bit 2's complement and then take the 2's complement
// because y movement on ps/2 format is opposite of touchpad.move function
my = my >> 1; // convert to 7 bits of data by dividing by 2
my = my & 0x7f; // don't allow sign extension
if ((0x20 & mstat) == 0x20) { // move the sign into
my = 0x80 | my; // the 8th bit position
}
my = (~my + 0x01); // change the sign of y data by taking the 2's complement (invert and add 1)
// zero out mx and my if over_flow or touchpad_error is set
if ((over_flow) || (touchpad_error)) {
mx = 0x00; // data is garbage so zero it out
my = 0x00;
}
// send the x and y data back via usb if either one is non-zero
if ((mx != 0x00) || (my != 0x00)) {
Mouse.move(mx,my);
}
//
// send the touchpad left and right button status over usb if no error
if (!touchpad_error) {
if ((0x01 & mstat) == 0x01) { // if left button set
left_button = 1;
}
else { // clear left button
left_button = 0;
}
if ((0x02 & mstat) == 0x02) { // if right button set
right_button = 1;
}
else { // clear right button
right_button = 0;
}
// Determine if the left or right touch pad buttons have changed since last polling cycle
button_change = (left_button ^ old_left_button) | (right_button ^ old_right_button);
// Don't send button status if there's no change since last time.
if (button_change){
Mouse.set_buttons(left_button, 0, right_button); // send button status
}
old_left_button = left_button; // remember new button status for next polling cycle
old_right_button = right_button;
}
//
// **************************************End of touchpad routine***********************************
//
delay(30); // wait 30ms before repeating next polling cycle
}