Andy K / MAX3100

MAX3100, an external serial device to add additional serial ports via SPI

Dependents:   FLIGHT_CONTROL_AND_COMMUNICATIONS_SYSTEM

example3.h@2:2a49171453d5, 2012-08-03 (annotated)

Committer:
AjK
Date:
Fri Aug 03 12:28:27 2012 +0000
Revision:
2:2a49171453d5
Parent:
1:46c8c60e744a 
Add example4.h and ISR user callback code

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AjK 0:055897ab699b 1 /*
AjK 0:055897ab699b 2 Copyright (c) 2011 Andy Kirkham
AjK 0:055897ab699b 3
AjK 0:055897ab699b 4 Permission is hereby granted, free of charge, to any person obtaining a copy
AjK 0:055897ab699b 5 of this software and associated documentation files (the "Software"), to deal
AjK 0:055897ab699b 6 in the Software without restriction, including without limitation the rights
AjK 0:055897ab699b 7 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
AjK 0:055897ab699b 8 copies of the Software, and to permit persons to whom the Software is
AjK 0:055897ab699b 9 furnished to do so, subject to the following conditions:
AjK 0:055897ab699b 10
AjK 0:055897ab699b 11 The above copyright notice and this permission notice shall be included in
AjK 0:055897ab699b 12 all copies or substantial portions of the Software.
AjK 0:055897ab699b 13
AjK 0:055897ab699b 14 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
AjK 0:055897ab699b 15 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
AjK 0:055897ab699b 16 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AjK 0:055897ab699b 17 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
AjK 0:055897ab699b 18 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
AjK 0:055897ab699b 19 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
AjK 0:055897ab699b 20 THE SOFTWARE.
AjK 0:055897ab699b 21 */
AjK 0:055897ab699b 22
AjK 0:055897ab699b 23 #ifdef MAX3100_EXAMPLE_COMPILE
AjK 0:055897ab699b 24
AjK 0:055897ab699b 25 /*
AjK 0:055897ab699b 26 * NOTE! Unlike examples 1 & 2 (which are tested in the real world) this example
AjK 0:055897ab699b 27 * is theoretical only as I have not tested it. It should work but if you try it
AjK 0:055897ab699b 28 * and it doesn't work let me know! It's shown here as a starting point to demo
AjK 0:055897ab699b 29 * how to share multiple MAX3100 interrupts and address multiple chips using
AjK 0:055897ab699b 30 * external hardware to manage each MAX3100's CS signal.
AjK 0:055897ab699b 31 *
AjK 0:055897ab699b 32 * Connecting up the MAX3100 for this test program. Note, to form a "loopback"
AjK 0:055897ab699b 33 * the MAX3100 TX pin (13) is connected to the RX pin (12). Don't forget thwe Xtal
AjK 0:055897ab699b 34 * and power pins that are not shown here. Although I do PullUp mode on the IRQ pin
AjK 0:055897ab699b 35 * I still needed a real external pull up resistor on the IRQ line. You may need one
AjK 0:055897ab699b 36 * also.
AjK 0:055897ab699b 37 *
AjK 0:055897ab699b 38 * __________
AjK 0:055897ab699b 39 * / \
AjK 0:055897ab699b 40 * Mbed p8 |---> 1| A0 Y0 | 15 -----> MAX0
AjK 0:055897ab699b 41 * p9 |---> 2| A1 Y1 | 14 -----> MAX1
AjK 0:055897ab699b 42 * p10 |---> 3| A2 Y2 | 13 -----> MAX2
AjK 0:055897ab699b 43 * p11 |---> 5| CS3 Y3 | 12 -----> MAX3 (and on to MAX7)
AjK 0:055897ab699b 44 * \__________/ TTL138 (Tie CS1 to +ve and CS2 to 0v)
AjK 0:055897ab699b 45 *
AjK 0:055897ab699b 46 * ____________
AjK 0:055897ab699b 47 * / \ U1
AjK 0:055897ab699b 48 * Mbed MOSI p5 |-------*---------------> 1| Din TX | 13 ------\
AjK 0:055897ab699b 49 * MISO p6 |-----*-|---------------> 2| Dout | |
AjK 0:055897ab699b 50 * SCLK p7 |---*-|-|---------------> 3| Sclk RX | 12 ------/
AjK 0:055897ab699b 51 * | | | MAX0 --> 4| CS |
AjK 0:055897ab699b 52 * p12 |-*-|-|-|---------------> 5| IRQ | MAX3100
AjK 0:055897ab699b 53 * | | | | +5v ---> 6| SHTD | Xtal and PWR not shown.
AjK 0:055897ab699b 54 * | | | | \____________/
AjK 0:055897ab699b 55 * | | | | ____________
AjK 0:055897ab699b 56 * | | | | / \ U2
AjK 0:055897ab699b 57 * | | | *---------------> 1| Din TX | 13 ------\
AjK 0:055897ab699b 58 * | | *-|---------------> 2| Dout | |
AjK 0:055897ab699b 59 * | *-|-|---------------> 3| Sclk RX | 12 ------/
AjK 0:055897ab699b 60 * | | | | MAX1 --> 4| CS |
AjK 0:055897ab699b 61 * *-|-|-|---------------> 5| IRQ | MAX3100
AjK 0:055897ab699b 62 * | | | | +5v ---> 6| SHTD | Xtal and PWR not shown.
AjK 0:055897ab699b 63 * | | | | \____________/
AjK 0:055897ab699b 64 * | | | | ____________
AjK 0:055897ab699b 65 * | | | | / \ U3
AjK 0:055897ab699b 66 * | | | \---------------> 1| Din TX | 13 ------\
AjK 0:055897ab699b 67 * | | \-----------------> 2| Dout | |
AjK 0:055897ab699b 68 * | \-------------------> 3| Sclk RX | 12 ------/
AjK 0:055897ab699b 69 * | MAX2 --> 4| CS |
AjK 0:055897ab699b 70 * \---------------------> 5| IRQ | MAX3100
AjK 0:055897ab699b 71 * +5v ---> 6| SHTD | Xtal and PWR not shown.
AjK 0:055897ab699b 72 * \____________/
AjK 0:055897ab699b 73 *
AjK 0:055897ab699b 74 * Assume a further 5 MAX3100 devices connected to the bus in the same way
AjK 0:055897ab699b 75 * to make a total of 8 MAX3100 serial devices connected to a single SPI bus.
AjK 0:055897ab699b 76 * Additionally, they all share the same interrupt signal. This is possible
AjK 0:055897ab699b 77 * because the MAX3100 IRQ output is open drain. So you will need an external 1k
AjK 0:055897ab699b 78 * pull up resistor on the IRQ signal.
AjK 0:055897ab699b 79 */
AjK 0:055897ab699b 80
AjK 0:055897ab699b 81 #include "mbed.h"
AjK 0:055897ab699b 82 #include "MAX3100.h"
AjK 0:055897ab699b 83
AjK 0:055897ab699b 84 Serial pc(USBTX, USBRX);
AjK 0:055897ab699b 85 SPI spi(p5, p6, p7);
AjK 0:055897ab699b 86 BusOut addr(p8, p9, p10);
AjK 0:055897ab699b 87 DigitalOut cs(p11);
AjK 0:055897ab699b 88 InterruptIn irq(p12);
AjK 0:055897ab699b 89 MAX3100 *max[8];
AjK 0:055897ab699b 90
AjK 0:055897ab699b 91 // Class used to decode the address and handle shared interrupts.
AjK 0:055897ab699b 92 class MAX3100_Addr {
AjK 0:055897ab699b 93 public:
AjK 0:055897ab699b 94 void cs_select(int device, int val) {
AjK 0:055897ab699b 95 addr = device & 0x7; // Select device.
AjK 0:055897ab699b 96 cs.write(val & 1); // Assert/deassert chip CS.
AjK 0:055897ab699b 97 }
AjK 0:055897ab699b 98 void isr(void) {
AjK 0:055897ab699b 99 for (int i = 0; i < 8; i++) {
AjK 0:055897ab699b 100 if (max[i] != (MAX3100 *)NULL) max[i]->isr();
AjK 0:055897ab699b 101 }
AjK 0:055897ab699b 102 }
AjK 0:055897ab699b 103 };
AjK 0:055897ab699b 104
AjK 0:055897ab699b 105 MAX3100_Addr address;
AjK 0:055897ab699b 106
AjK 0:055897ab699b 107 int main() {
AjK 0:055897ab699b 108 int index;
AjK 0:055897ab699b 109
AjK 0:055897ab699b 110 cs = 1;
AjK 0:055897ab699b 111
AjK 0:055897ab699b 112 // Set the PC USB serial baud rate.
AjK 0:055897ab699b 113 pc.baud(115200);
AjK 0:055897ab699b 114
AjK 0:055897ab699b 115 // Format the SPI interface.
AjK 0:055897ab699b 116 spi.format(16, 0);
AjK 0:055897ab699b 117 spi.frequency(MAX3100_SPI_FREQ);
AjK 0:055897ab699b 118
AjK 0:055897ab699b 119 // Create the 8 devices and set them up.
AjK 0:055897ab699b 120 for (int index = 0; index < 8; index++) {
AjK 0:055897ab699b 121 max[index] = new MAX3100(&spi, NC, NC);
AjK 0:055897ab699b 122 max[index]->setDevice(index);
AjK 0:055897ab699b 123 max[index]->enableRxIrq();
AjK 0:055897ab699b 124 max[index]->enableTxIrq();
AjK 0:055897ab699b 125 max[index]->attach_cs(&address, &MAX3100_Addr::cs_select);
AjK 1:46c8c60e744a 126 max[index]->irqMask(p12); // Tell objects where shared InterruptIn is.
AjK 0:055897ab699b 127 }
AjK 0:055897ab699b 128
AjK 0:055897ab699b 129 // Connect the interrupt signal.
AjK 0:055897ab699b 130 irq.fall(&address, &MAX3100_Addr::isr);
AjK 0:055897ab699b 131
AjK 0:055897ab699b 132 // Any byte received on the "USB serial port" is sent to all MAX3100 devices.
AjK 0:055897ab699b 133 // Any byte received by a MAX3100 device is sent to the "USB serial port".
AjK 0:055897ab699b 134 while (1) {
AjK 0:055897ab699b 135 if (pc.readable()) {
AjK 0:055897ab699b 136 int c = pc.getc();
AjK 0:055897ab699b 137 for (index = 0; index < 8; index++) {
AjK 0:055897ab699b 138 if (max[index] != (MAX3100 *)NULL) {
AjK 0:055897ab699b 139 max[index]->putc(c);
AjK 0:055897ab699b 140 }
AjK 0:055897ab699b 141 }
AjK 0:055897ab699b 142 }
AjK 0:055897ab699b 143 for (index = 0; index < 8; index++) {
AjK 0:055897ab699b 144 if (max[index] != (MAX3100 *)NULL) {
AjK 0:055897ab699b 145 if (max[index]->readable()) {
AjK 0:055897ab699b 146 pc.putc(max[index]->getc());
AjK 0:055897ab699b 147 }
AjK 0:055897ab699b 148 }
AjK 0:055897ab699b 149 }
AjK 0:055897ab699b 150 }
AjK 0:055897ab699b 151 }
AjK 0:055897ab699b 152
AjK 0:055897ab699b 153 #endif