Craig Raslawski / Mbed 2 deprecated MCP23S17_IO_Expander

4180Lab1Part3

Dependencies:   MCP23S17 mbed

Fork of MCP23S17_Basic_IO_Demo by jim hamblen

part3.cpp@3:3081585fbce1, 2017-02-27 (annotated)

Committer:
CRaslawski
Date:
Mon Feb 27 22:31:04 2017 +0000
Revision:
3:3081585fbce1
initial commit

Who changed what in which revision?

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CRaslawski 3:3081585fbce1 1 // A simple IO demo using the MCP23S17 library
CRaslawski 3:3081585fbce1 2 //
CRaslawski 3:3081585fbce1 3 // MCP23S17 Library Copyright (c) 2010 Romilly Cocking
CRaslawski 3:3081585fbce1 4 // Released under the MIT License: http://mbed.org/license/mit
CRaslawski 3:3081585fbce1 5 //
CRaslawski 3:3081585fbce1 6 // See http://mbed.org/users/romilly/notebook/mcp23s17-addressable-16-bit-io-expander-with-spi/
CRaslawski 3:3081585fbce1 7 //
CRaslawski 3:3081585fbce1 8 //
CRaslawski 3:3081585fbce1 9 // MCP23S17 datasheet http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf
CRaslawski 3:3081585fbce1 10 // uses MCP23S17 library version 0.4
CRaslawski 3:3081585fbce1 11
CRaslawski 3:3081585fbce1 12 #include "mbed.h"
CRaslawski 3:3081585fbce1 13 #include "MCP23S17.h"
CRaslawski 3:3081585fbce1 14 // Create SPI bus
CRaslawski 3:3081585fbce1 15 SPI spi(p11, p12, p13);
CRaslawski 3:3081585fbce1 16 //
CRaslawski 3:3081585fbce1 17 // Wiring Connections:
CRaslawski 3:3081585fbce1 18 // mbed p5,p6,p7 are tied to MCP23S17 SI, SO, SCK pins
CRaslawski 3:3081585fbce1 19 // mbed p20 to MCP23S17 CS
CRaslawski 3:3081585fbce1 20 // MCP23S17 reset pin pulled high
CRaslawski 3:3081585fbce1 21 // MCP23S17 GPA0 connected to GPB0 for loopback test
CRaslawski 3:3081585fbce1 22 // A0, A1, A2 of the MCP23S17 are tied to ground on the breadboard, so the 8-bit address for writes is 0x40
CRaslawski 3:3081585fbce1 23 // This is referred to as the opcode in the device datasheet
CRaslawski 3:3081585fbce1 24 char Opcode = 0x40;
CRaslawski 3:3081585fbce1 25
CRaslawski 3:3081585fbce1 26 // Next create a MCP23S17
CRaslawski 3:3081585fbce1 27 // mbed p20 is connected to ~chipSelect on the MCP23S17
CRaslawski 3:3081585fbce1 28 MCP23S17 chip = MCP23S17(spi, p20, Opcode);
CRaslawski 3:3081585fbce1 29
CRaslawski 3:3081585fbce1 30 // Optional software reset - mbed p14 to MCP23S17 reset pin
CRaslawski 3:3081585fbce1 31 // DigitalOut reset(p14);
CRaslawski 3:3081585fbce1 32
CRaslawski 3:3081585fbce1 33 DigitalOut led1(LED1); // mbed LED1 is used for test status display
CRaslawski 3:3081585fbce1 34
CRaslawski 3:3081585fbce1 35 int main()
CRaslawski 3:3081585fbce1 36 {
CRaslawski 3:3081585fbce1 37 // The MCP23S17 reset pin can just be pulled high, since it has a power on reset circuit.
CRaslawski 3:3081585fbce1 38 // The reset pin can be used for a software forced reset by pulling it low with an mbed GPIO pin.
CRaslawski 3:3081585fbce1 39 // But just leave it pulled high for this simple demo code.
CRaslawski 3:3081585fbce1 40 // After a power on reset, both IO ports default to input mode
CRaslawski 3:3081585fbce1 41 //
CRaslawski 3:3081585fbce1 42 // Here is the optional code for a software reset
CRaslawski 3:3081585fbce1 43 // reset = 0;
CRaslawski 3:3081585fbce1 44 // wait_us(1);
CRaslawski 3:3081585fbce1 45 // reset = 1;
CRaslawski 3:3081585fbce1 46 //
CRaslawski 3:3081585fbce1 47 // Set all 8 Port A bits to output direction
CRaslawski 3:3081585fbce1 48 chip.direction(PORT_A, 0x00);
CRaslawski 3:3081585fbce1 49 // Set all 8 Port B bits to input direction
CRaslawski 3:3081585fbce1 50 chip.direction(PORT_B, 0xFF);
CRaslawski 3:3081585fbce1 51 led1=0;
CRaslawski 3:3081585fbce1 52 // Start Loopback test sending out and reading back values
CRaslawski 3:3081585fbce1 53 // loopback test uses A0 and B0 pins - so use a wire to jumper those two pins on MCP23S17 together
CRaslawski 3:3081585fbce1 54
CRaslawski 3:3081585fbce1 55 /*
CRaslawski 3:3081585fbce1 56 while (1) {
CRaslawski 3:3081585fbce1 57 // write 0xAA to MCP23S17 Port A
CRaslawski 3:3081585fbce1 58 chip.write(PORT_A, 0xAA);
CRaslawski 3:3081585fbce1 59 wait(.5);
CRaslawski 3:3081585fbce1 60 // read back value from MCP23S17 Port B and display B0 on mbed led1
CRaslawski 3:3081585fbce1 61 led1 = chip.read(PORT_B)& 0x01;
CRaslawski 3:3081585fbce1 62 // write 0x55 to MCP23S17 Port A
CRaslawski 3:3081585fbce1 63 chip.write(PORT_A, 0x55);
CRaslawski 3:3081585fbce1 64 wait(.5);
CRaslawski 3:3081585fbce1 65 // read back value from MCP23S17 Port B and display B0 on mbed led1
CRaslawski 3:3081585fbce1 66 led1 = chip.read(PORT_B)& 0x01;
CRaslawski 3:3081585fbce1 67 // led1 should blink slowly when it is all working
CRaslawski 3:3081585fbce1 68 }
CRaslawski 3:3081585fbce1 69 */
CRaslawski 3:3081585fbce1 70 //run while loop to check if button has been pushed down
CRaslawski 3:3081585fbce1 71 //read port B for 0x01
CRaslawski 3:3081585fbce1 72 bool ledOn = false;
CRaslawski 3:3081585fbce1 73 while(1) {
CRaslawski 3:3081585fbce1 74 //wait(0.5);
CRaslawski 3:3081585fbce1 75 if( chip.read(PORT_B)&0x01 ){ //if button is pushed down, light LED
CRaslawski 3:3081585fbce1 76 //wait();
CRaslawski 3:3081585fbce1 77 if(ledOn) { //if on, turn led off
CRaslawski 3:3081585fbce1 78 chip.write(PORT_A, 0x00);
CRaslawski 3:3081585fbce1 79 ledOn = false;
CRaslawski 3:3081585fbce1 80 }
CRaslawski 3:3081585fbce1 81 else { //if led off, turn on.
CRaslawski 3:3081585fbce1 82 chip.write(PORT_A, 0x01); // write 1 to LED pin, turning it on
CRaslawski 3:3081585fbce1 83 ledOn = true;
CRaslawski 3:3081585fbce1 84 }
CRaslawski 3:3081585fbce1 85 }
CRaslawski 3:3081585fbce1 86 wait(.2);
CRaslawski 3:3081585fbce1 87 //else{
CRaslawski 3:3081585fbce1 88 // chip.write(PORT_A, 0x00); // write 1 to LED port, turning off
CRaslawski 3:3081585fbce1 89 //}
CRaslawski 3:3081585fbce1 90
CRaslawski 3:3081585fbce1 91 }
CRaslawski 3:3081585fbce1 92 }
CRaslawski 3:3081585fbce1 93