Possible UNO R4 compatability issue #48
Description
More info in this forum thread:
https://forums.adafruit.com/viewtopic.php?t=220309
Test sketch to use for demonstrating the issue:
/*********************************************************
This is a library for the MPR121 12-channel Capacitive touch sensor
Designed specifically to work with the MPR121 Breakout in the Adafruit shop
----> https://www.adafruit.com/products/
These sensors use I2C communicate, at least 2 pins are required
to interface
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!
Written by Limor Fried/Ladyada for Adafruit Industries.
BSD license, all text above must be included in any redistribution
**********************************************************/
#include <Wire.h>
#include "Adafruit_MPR121.h"
#ifndef _BV
#define _BV(bit) (1 << (bit))
#endif
// You can have up to 4 on one i2c bus but one is enough for testing!
Adafruit_MPR121 cap = Adafruit_MPR121();
// Keeps track of the last pins touched
// so we know when buttons are 'released'
uint16_t lasttouched = 0;
uint16_t currtouched = 0;
void setup() {
Serial.begin(9600);
while (!Serial) { // needed to keep leonardo/micro from starting too fast!
delay(10);
}
Serial.println("Adafruit MPR121 Capacitive Touch sensor test");
// Default address is 0x5A, if tied to 3.3V its 0x5B
// If tied to SDA its 0x5C and if SCL then 0x5D
if (!cap.begin(0x5A)) {
Serial.println("MPR121 not found, check wiring?");
while (1);
}
Serial.println("MPR121 found!");
// adding the next line per this forum thread: https://forums.adafruit.com/viewtopic.php?t=220309
cap.setAutoconfig(true);
}
void loop() {
// Get the currently touched pads
currtouched = cap.touched();
for (uint8_t i=0; i<12; i++) {
// it if *is* touched and *wasnt* touched before, alert!
if ((currtouched & _BV(i)) && !(lasttouched & _BV(i)) ) {
Serial.print(i); Serial.println(" touched");
}
// if it *was* touched and now *isnt*, alert!
if (!(currtouched & _BV(i)) && (lasttouched & _BV(i)) ) {
Serial.print(i); Serial.println(" released");
}
}
// reset our state
lasttouched = currtouched;
// comment out this line for detailed data from the sensor!
// return;
// debugging info, what
Serial.print("\t\t\t\t\t\t\t\t\t\t\t\t\t 0x"); Serial.println(cap.touched(), HEX);
Serial.print("Filt: ");
for (uint8_t i=0; i<12; i++) {
Serial.print(cap.filteredData(i)); Serial.print("\t");
}
Serial.println();
Serial.print("Base: ");
for (uint8_t i=0; i<12; i++) {
Serial.print(cap.baselineData(i)); Serial.print("\t");
}
Serial.println();
// put a delay so it isn't overwhelming
delay(100);
}Different setups seem to experience the issue more readily than others. Commenting out the delay(100); in the loop() also seems to make the issue show up faster.
The issue appears as saturated values in the reported touch values:
Filt: 696 538 356 274 712 715 716 716 720 720 722 713
Base: 704 700 716 708 712 712 716 716 716 716 720 712
0 touched
4 released
0xF
Filt: 591 437 296 256 713 716 717 717 720 719 722 714
Base: 704 700 716 708 712 712 716 716 716 716 720 712
4 touched
5 touched
6 touched
7 touched
8 touched
9 touched
10 touched
11 touched
0xFFF
Filt: 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535
Base: 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020
0xFFF
Filt: 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535
Base: 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020
0xFFF
Filt: 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535
Base: 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020 1020
Additionally - the MPR121 seems to be stuck at this point. The LED attached to the INT pin becomes stuck on. And the MPR121 is generally unresponsive.