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mpr121: Initial implementation

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This module implements support for the Grove I2C touch sensor
(mpr121).

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Zion Orent <zorent@ics.com>
Signed-off-by: John Van Drasek <john.r.van.drasek@intel.com>
This commit is contained in:
Jon Trulson
2014-12-09 13:44:01 -07:00
committed by John Van Drasek
parent 2eb0047643
commit 0c63500b36
8 changed files with 498 additions and 0 deletions
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src/mpr121/mpr121.cxx Normal file
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/*
* Author: Jon Trulson <jtrulson@ics.com>
* Copyright (c) 2014 Intel Corporation.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include <iostream>
#include <string>
#include "mpr121.h"
using namespace upm;
using namespace std;
MPR121::MPR121(int bus, uint8_t address)
{
// setup our i2c link
m_i2c = mraa_i2c_init(bus);
m_addr = address;
mraa_result_t ret = mraa_i2c_address(m_i2c, m_addr);
if (ret != MRAA_SUCCESS)
cerr << "MPR121: Could not initialize i2c bus. " << endl;
m_buttonStates = 0;
m_overCurrentFault = false;
}
MPR121::~MPR121()
{
mraa_i2c_stop(m_i2c);
}
mraa_result_t MPR121::writeBytes(uint8_t reg, uint8_t *buffer, unsigned int len)
{
if (!len || !buffer)
return MRAA_SUCCESS;
// create a buffer 1 byte larger than the supplied buffer,
// store the register in the first byte
uint8_t buf2[len + 1];
buf2[0] = reg;
// copy in the buffer after the reg byte
for (int i=1; i<(len + 1); i++)
buf2[i] = buffer[i-1];
mraa_i2c_address(m_i2c, m_addr);
return mraa_i2c_write(m_i2c, buf2, len + 1);
}
void MPR121::readBytes(uint8_t reg, uint8_t *buffer, unsigned int len)
{
if (!len || !buffer)
return;
// The usual mraa_i2c_read() does not work here, so we need to
// read each byte individually.
for (int i=0; i<len; i++)
buffer[i] = mraa_i2c_read_byte_data(m_i2c, reg + i);
return;
}
bool MPR121::configAN3944()
{
// Configure the mpr121 chip as recommended in the AN3944 MPR121
// Quick Start Guide
mraa_result_t rv;
// First, turn off all electrodes by zeroing out the Electrode Configuration
// register.
// If this one fails, it's unlikely any of the others will succeed.
uint8_t eleConf = 0x00;
if ((rv = writeBytes(0x5e, &eleConf, 1)) != MRAA_SUCCESS)
{
cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
return false;
}
// Section A
// Filtering when data is greater than baseline
// regs 0x2b-0x2e
uint8_t sectA[] = { 0x01, 0x01, 0x00, 0x00 };
if ((rv = writeBytes(0x2b, sectA, 4)) != MRAA_SUCCESS)
{
cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
return false;
}
// Section B
// Filtering when data is less than baseline
// regs 0x2f-0x32
uint8_t sectB[] = { 0x01, 0x01, 0xff, 0x02 };
if ((rv = writeBytes(0x2f, sectB, 4)) != MRAA_SUCCESS)
{
cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
return false;
}
// Section C
// Touch Threshold/Release registers, ELE0-ELE11
// regs 0x41-0x58
// __T_ __R_
uint8_t sectC[] = { 0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a,
0x0f, 0x0a };
if ((rv = writeBytes(0x41, sectC, 24)) != MRAA_SUCCESS)
{
cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
return false;
}
// Section D
// Filter configuration
// reg 0x5d
uint8_t filterConf = 0x04;
if ((rv = writeBytes(0x5d, &filterConf, 1)) != MRAA_SUCCESS)
{
cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
return false;
}
// Section F
// Autoconfiguration registers
// regs 0x7b-0x7f
uint8_t sectF0 = 0x0b;
if ((rv = writeBytes(0x7b, &sectF0, 1)) != MRAA_SUCCESS)
{
cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
return false;
}
uint8_t sectF1[] = { 0x9c, 0x65, 0x8c };
if ((rv = writeBytes(0x7d, sectF1, 3)) != MRAA_SUCCESS)
{
cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
return false;
}
// Section E - this one must be set last, and switches to run mode
// Enable all 12 electrodes, and set a pre-calibration to avoid
// excessive calibration delay on startup.
// reg 0x5e
eleConf = 0x8c;
if ((rv = writeBytes(0x5e, &eleConf, 1)) != MRAA_SUCCESS)
{
cerr << __FUNCTION__ << ": " << __LINE__<< ": I2C write failed." << endl;
return false;
}
return true;
}
void MPR121::readButtons()
{
uint8_t rv;
uint8_t buffer[2];
// read in the 2 bytes at register 0x00-0x01, and setup the member
// variables accordingly.
readBytes(0x00, buffer, 2);
m_buttonStates = (buffer[0] | ((buffer[1] & 0x1f) << 8));
if (buffer[1] & 0x80)
m_overCurrentFault = true;
else
m_overCurrentFault = false;
return;
}