File content as of revision 2:2a49171453d5:

/*
    Copyright (c) 2011 Andy Kirkham
 
    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.
*/

#ifdef MAX3100_EXAMPLE_COMPILE

/*
 * NOTE! Unlike examples 1 & 2 (which are tested in the real world) this example
 * is theoretical only as I have not tested it. It should work but if you try it 
 * and it doesn't work let me know! It's shown here as a starting point to demo
 * how to share multiple MAX3100 interrupts and address multiple chips using
 * external hardware to manage each MAX3100's CS signal.
 * 
 * Connecting up the MAX3100 for this test program. Note, to form a "loopback"
 * the MAX3100 TX pin (13) is connected to the RX pin (12). Don't forget thwe Xtal
 * and power pins that are not shown here. Although I do PullUp mode on the IRQ pin
 * I still needed a real external pull up resistor on the IRQ line. You may need one
 * also.
 *
 *                      __________
 *                     /          \
 *      Mbed p8 |---> 1| A0    Y0 | 15 -----> MAX0
 *           p9 |---> 2| A1    Y1 | 14 -----> MAX1
 *          p10 |---> 3| A2    Y2 | 13 -----> MAX2
 *          p11 |---> 5| CS3   Y3 | 12 -----> MAX3 (and on to MAX7)
 *                     \__________/ TTL138 (Tie CS1 to +ve and CS2 to 0v)
 *
 *                                          ____________
 *                                         /            \ U1
 * Mbed MOSI p5 |-------*---------------> 1| Din     TX | 13 ------\
 *      MISO p6 |-----*-|---------------> 2| Dout       |          |
 *      SCLK p7 |---*-|-|---------------> 3| Sclk    RX | 12 ------/
 *                  | | |        MAX0 --> 4| CS         |
 *          p12 |-*-|-|-|---------------> 5| IRQ        | MAX3100 
 *                | | | |        +5v ---> 6| SHTD       | Xtal and PWR not shown.
 *                | | | |                  \____________/
 *                | | | |                   ____________
 *                | | | |                  /            \ U2
 *                | | | *---------------> 1| Din     TX | 13 ------\
 *                | | *-|---------------> 2| Dout       |          |
 *                | *-|-|---------------> 3| Sclk    RX | 12 ------/
 *                | | | |        MAX1 --> 4| CS         |
 *                *-|-|-|---------------> 5| IRQ        | MAX3100
 *                | | | |        +5v ---> 6| SHTD       | Xtal and PWR not shown.
 *                | | | |                  \____________/
 *                | | | |                   ____________
 *                | | | |                  /            \ U3
 *                | | | \---------------> 1| Din     TX | 13 ------\
 *                | | \-----------------> 2| Dout       |          |
 *                | \-------------------> 3| Sclk    RX | 12 ------/
 *                |              MAX2 --> 4| CS         |
 *                \---------------------> 5| IRQ        | MAX3100
 *                               +5v ---> 6| SHTD       | Xtal and PWR not shown.
 *                                         \____________/
 *
 * Assume a further 5 MAX3100 devices connected to the bus in the same way
 * to make a total of 8 MAX3100 serial devices connected to a single SPI bus.
 * Additionally, they all share the same interrupt signal. This is possible 
 * because the MAX3100 IRQ output is open drain. So you will need an external 1k
 * pull up resistor on the IRQ signal.
 */

#include "mbed.h"
#include "MAX3100.h"

Serial       pc(USBTX, USBRX);
SPI          spi(p5, p6, p7);
BusOut       addr(p8, p9, p10);
DigitalOut   cs(p11);
InterruptIn  irq(p12);
MAX3100      *max[8];

// Class used to decode the address and handle shared interrupts.
class MAX3100_Addr {
public:
    void cs_select(int device, int val) { 
        addr = device & 0x7; // Select device.
        cs.write(val & 1);   // Assert/deassert chip CS.
    }
    void isr(void) {
        for (int i = 0; i < 8; i++) {
            if (max[i] != (MAX3100 *)NULL) max[i]->isr();
        }
    }
};

MAX3100_Addr address;

int main() {
    int index;
    
    cs = 1;
    
    // Set the PC USB serial baud rate.
    pc.baud(115200);

    // Format the SPI interface.    
    spi.format(16, 0);
    spi.frequency(MAX3100_SPI_FREQ);
    
    // Create the 8 devices and set them up.
    for (int index = 0; index < 8; index++) {
        max[index] = new MAX3100(&spi, NC, NC);  
        max[index]->setDevice(index);   
        max[index]->enableRxIrq();
        max[index]->enableTxIrq();
        max[index]->attach_cs(&address, &MAX3100_Addr::cs_select);
        max[index]->irqMask(p12); // Tell objects where shared InterruptIn is.
    }
    
    // Connect the interrupt signal.
    irq.fall(&address, &MAX3100_Addr::isr);
    
    // Any byte received on the "USB serial port" is sent to all MAX3100 devices.
    // Any byte received by a MAX3100 device is sent to the "USB serial port".
    while (1) {
        if (pc.readable()) {
            int c = pc.getc();
            for (index = 0; index < 8; index++) {
                if (max[index] != (MAX3100 *)NULL) {
                    max[index]->putc(c);            
                }
            }            
        }
        for (index = 0; index < 8; index++) {
            if (max[index] != (MAX3100 *)NULL) {
                if (max[index]->readable()) {
                    pc.putc(max[index]->getc());
                }    
            }
        }        
    }    
}

#endif