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/*
 * MCP4822A - DAC array library.
 *
 * Copyright (c) 2011 Steven Beard, UK Astronomy Technology Centre.
 *
 * 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 "mbed.h"
#include "MCP4822A.h"

using namespace mbed;

/*+
 * Interface to an array of MCP4822 12-bit dual-output DACs daisy chained
 * on an SPI bus and selected using DigitalOut pins.
 *
 * For a detailed API description see MCP4822.h.
 *-
 */
// Constructor
MCP4822A::MCP4822A(int ndacs, PinName mosi, PinName sclk, PinName ncslist[], PinName nldac) : _spi(mosi, NC, sclk) {

    // Create an array of DigitalOut objects connected to each NCS pin.
    int i;
    _ndacs = (ndacs > 0) ? ndacs : 1;
    _ncs_array = new DigitalOut*[ _ndacs ];
    for (i=0; i<_ndacs; i++) {
        _ncs_array[i] = new DigitalOut( ncslist[i] );
    }

    // The LDAC pin is optional.
    if (nldac == NC) {
        // LDAC is not connected for this DAC.
        _latched = 0;
        _nldac = NULL;
    } else {
        // LDAC is connected - create a DigitalOut object connected to it.
        _latched = 1;
        _nldac = new DigitalOut( nldac );
    }

    // Initialise the DAC SPI interface.
    _init();
}

// Destructor
MCP4822A::~MCP4822A() {

    // Before destroying the object, shut down all the chips.
    shdn_all();

    // Delete all the NCS DigitalOut objects and the array pointing to
    // them.
    int i;
    for (i=0; i<_ndacs; i++) {
        delete _ncs_array[i];
    }
    delete [] _ncs_array;

    // Delete the LDAC DigitalOut object if it exists.
    if (_latched ) delete _nldac;
}

// Initialise SPI interface.
void MCP4822A::_init() {

    // Set up the SPI for 16-bit values (12-bit + 4 command bits) and mode 0.
    _spi.format(16, 0);

    // Start with all the CS and LDAC signals high (disabled)
    int i;
    for (i=0; i<_ndacs; i++) {
        _ncs_array[i]->write(1);
    }

    if (_latched ) _nldac->write(1);
    return;
}

// Set SPI clock frequency.
void MCP4822A::frequency( int freq ) {

    // Set the SPI interface clock frequency in Hz.
    _spi.frequency( freq );
    return;
}

/*
 * Note: There is a lot of code in common between the following 4 functions.
 * The code is kept in line to keep it efficient. Could the functions have
 * been written as templates?
 */
// Write to DAC channel A with gain 1.
void MCP4822A::writeA1(int dac, int value) {

    // Set up the command register with the appropriate value.
    // For efficiency, the caller is assumed to have checked dac.
    int reg;
    reg = (value & 0x0FFF) | MCP4822_REG_A1;

    // Select the DAC chip, write to its command register and
    // then unselect the DAC chip.
    _ncs_array[dac]->write(0);
    _spi.write(reg);
    _ncs_array[dac]->write(1);
    return;
}

// Write to DAC channel A with gain 2.
void MCP4822A::writeA2(int dac, int value) {

    // Set up the command register with the appropriate value.
    // For efficiency, the caller is assumed to have checked dac.
    int reg;
    reg = (value & 0x0FFF) | MCP4822_REG_A2;

    // Select the DAC chip, write to its command register and then
    // unselect the DAC chip.
    _ncs_array[dac]->write(0);
    _spi.write(reg);
    _ncs_array[dac]->write(1);
    return;
}

// Write to DAC channel B with gain 1.
void MCP4822A::writeB1(int dac, int value) {

    // Set up the command register with the appropriate value.
    // For efficiency, the caller is assumed to have checked dac.
    int reg;
    reg = (value & 0x0FFF) | MCP4822_REG_B1;

    // Select the DAC chip, write to its command register and then
    // unselect the DAC chip.
    _ncs_array[dac]->write(0);
    _spi.write(reg);
    _ncs_array[dac]->write(1);
    return;
}

// Write to DAC channel B with gain 2.
void MCP4822A::writeB2(int dac, int value) {

    // Set up the command register with the appropriate value.
    // For efficiency, the caller is assumed to have checked dac.
    int reg;
    reg = (value & 0x0FFF) | MCP4822_REG_B2;

    // Select the DAC chip, write to its command register and then
    // unselect the DAC chip.
    _ncs_array[dac]->write(0);
    _spi.write(reg);
    _ncs_array[dac]->write(1);
    return;
}

// Write an array of values to the DACs.
void MCP4822A::write(int nchans, int values[], int gain, int latch) {

    // nchans must be at least 1 but less than or equal to ndacs x 2.
    if (nchans < 1) nchans = 1;
    const int maxchans = _ndacs * 2;
    if (nchans > maxchans) nchans = maxchans;

    if (latch && _latched)
        latch_disable();

    int i, dac;
    if ( gain == 2 ) {

        for (i=0; i<nchans;) {
            dac = i/2;
            writeA2(dac, values[i]);
            i++;
            if (i < nchans) {
                writeB2(dac, values[i]);
                i++;
            } else break;
        }
    } else {

        for (i=0; i<nchans;) {
            dac = i/2;
            writeA1(dac, values[i]);
            i++;
            if (i < nchans) {
                writeB1(dac, values[i]);
                i++;
            } else break;
        }
    }

    // Automatically latch the new voltages if the latch flag is 1.
    if (latch && _latched)
        latch_enable();
    return;
}

// Convert a voltage into a 12-bit value.
int MCP4822A::voltage2value( float voltage, int gain ) {

    int value = int(4096000.0 * abs(voltage) / float(MCP4822_VREF * gain));
    if ( value > 0x0FFF ) value = 0x0FFF;
    return value;
}

// Convert a 12-bit value into a voltage.
float MCP4822A::value2voltage( int value, int gain ) {

    float voltage = value * MCP4822_VREF * gain / 4096000.0;
    return voltage;
}

// Set latch signal to "enable".
void MCP4822A::latch_enable() {

    // Latch all chips. There should be a delay of at least T_LS=40
    // nanoseconds between the last CS rising edge and the LDAC falling
    // edge. The software function calls seem to be sufficient to
    // introduce that delay. A delay may be inserted here if this
    // software is ported to a faster processor.
    if (_latched) _nldac->write(0);
    // The LDAC pulse width must be at least T_LD=100 nanoseconds long.
    // A delay can be inserted here if necessary, but so far this has
    // not been needed (see above).
    return;
}

// Set latch signal to "disable".
void MCP4822A::latch_disable() {

    // Disable latch for all chips.
    if (_latched) _nldac->write(1);
    return;
}

// Shut down one chip.
void MCP4822A::shdn( int dac ) {

    // Shut down one particular chip
    _ncs_array[dac]->write(0);
    _spi.write(MCP4822_REG_SHDN);
    _ncs_array[dac]->write(1);
    return;
}

// Shut down all chips.
void MCP4822A::shdn_all( ) {

    // Shut down all chips
    int dac;
    for (dac=0; dac<_ndacs; dac++) {
        shdn( dac );
    }
    latch_disable();
    return;
}