ECE 4180 Labs / Mbed 2 deprecated 4180_Lab1_IOExpandor

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Dependencies:   MCP23S17 mbed

Fork of MCP23S17_Basic_IO_Demo by jim hamblen

main.cpp@3:cf5a7230ef4d, 2016-09-25 (annotated)

Committer:
jeremycai3721
Date:
Sun Sep 25 20:16:55 2016 +0000
Revision:
3:cf5a7230ef4d
Parent:
2:934a0500abde 
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4180_1 2:934a0500abde 1 // A simple IO demo using the MCP23S17 library
4180_1 2:934a0500abde 2 //
4180_1 2:934a0500abde 3 // MCP23S17 Library Copyright (c) 2010 Romilly Cocking
4180_1 2:934a0500abde 4 // Released under the MIT License: http://mbed.org/license/mit
4180_1 2:934a0500abde 5 //
4180_1 2:934a0500abde 6 // See http://mbed.org/users/romilly/notebook/mcp23s17-addressable-16-bit-io-expander-with-spi/
4180_1 2:934a0500abde 7 //
4180_1 2:934a0500abde 8 //
4180_1 2:934a0500abde 9 // MCP23S17 datasheet http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf
4180_1 2:934a0500abde 10 // uses MCP23S17 library version 0.4
4180_1 0:12f4911d7ba0 11
4180_1 0:12f4911d7ba0 12 #include "mbed.h"
4180_1 0:12f4911d7ba0 13 #include "MCP23S17.h"
4180_1 2:934a0500abde 14 // Create SPI bus
4180_1 0:12f4911d7ba0 15 SPI spi(p5, p6, p7);
4180_1 2:934a0500abde 16 //
4180_1 2:934a0500abde 17 // Wiring Connections:
4180_1 0:12f4911d7ba0 18 // mbed p5,p6,p7 are tied to MCP23S17 SI, SO, SCK pins
4180_1 2:934a0500abde 19 // mbed p20 to MCP23S17 CS
4180_1 2:934a0500abde 20 // MCP23S17 reset pin pulled high
4180_1 2:934a0500abde 21 // MCP23S17 GPA0 connected to GPB0 for loopback test
4180_1 0:12f4911d7ba0 22 // A0, A1, A2 of the MCP23S17 are tied to ground on the breadboard, so the 8-bit address for writes is 0x40
4180_1 0:12f4911d7ba0 23 // This is referred to as the opcode in the device datasheet
4180_1 2:934a0500abde 24 char Opcode = 0x40;
4180_1 0:12f4911d7ba0 25
4180_1 0:12f4911d7ba0 26 // Next create a MCP23S17
4180_1 0:12f4911d7ba0 27 // mbed p20 is connected to ~chipSelect on the MCP23S17
4180_1 2:934a0500abde 28 MCP23S17 chip = MCP23S17(spi, p20, Opcode);
4180_1 0:12f4911d7ba0 29
4180_1 2:934a0500abde 30 // Optional software reset - mbed p14 to MCP23S17 reset pin
4180_1 2:934a0500abde 31 // DigitalOut reset(p14);
4180_1 1:70e1ebe47253 32
4180_1 0:12f4911d7ba0 33 DigitalOut led1(LED1); // mbed LED1 is used for test status display
4180_1 0:12f4911d7ba0 34
jeremycai3721 3:cf5a7230ef4d 35 int B0;
jeremycai3721 3:cf5a7230ef4d 36
4180_1 0:12f4911d7ba0 37 int main() {
4180_1 1:70e1ebe47253 38 // The MCP23S17 reset pin can just be pulled high, since it has a power on reset circuit.
4180_1 1:70e1ebe47253 39 // The reset pin can be used for a software forced reset by pulling it low with an mbed GPIO pin.
4180_1 1:70e1ebe47253 40 // But just leave it pulled high for this simple demo code.
4180_1 0:12f4911d7ba0 41 // After a power on reset, both IO ports default to input mode
4180_1 0:12f4911d7ba0 42 //
4180_1 1:70e1ebe47253 43 // Here is the optional code for a software reset
4180_1 1:70e1ebe47253 44 // reset = 0;
4180_1 1:70e1ebe47253 45 // wait_us(1);
4180_1 1:70e1ebe47253 46 // reset = 1;
4180_1 1:70e1ebe47253 47 //
4180_1 0:12f4911d7ba0 48 // Set all 8 Port A bits to output direction
4180_1 0:12f4911d7ba0 49 chip.direction(PORT_A, 0x00);
4180_1 0:12f4911d7ba0 50 // Set all 8 Port B bits to input direction
4180_1 0:12f4911d7ba0 51 chip.direction(PORT_B, 0xFF);
4180_1 0:12f4911d7ba0 52 led1=0;
4180_1 0:12f4911d7ba0 53 // Start Loopback test sending out and reading back values
4180_1 0:12f4911d7ba0 54 // loopback test uses A0 and B0 pins - so use a wire to jumper those two pins on MCP23S17 together
4180_1 0:12f4911d7ba0 55 while (1) {
jeremycai3721 3:cf5a7230ef4d 56 // read in B0 and see if it's 0 (button being pressed)
jeremycai3721 3:cf5a7230ef4d 57 B0 = chip.read(PORT_B)& 0x01;
jeremycai3721 3:cf5a7230ef4d 58 if (B0 == 0)
jeremycai3721 3:cf5a7230ef4d 59 {
jeremycai3721 3:cf5a7230ef4d 60 chip.write(PORT_A,1); // output 1 at A0 to light up LED
jeremycai3721 3:cf5a7230ef4d 61 } else {
jeremycai3721 3:cf5a7230ef4d 62 chip.write(PORT_A,0); // turn off LED
jeremycai3721 3:cf5a7230ef4d 63 }
jeremycai3721 3:cf5a7230ef4d 64
jeremycai3721 3:cf5a7230ef4d 65 // if yes, out put Port A0 to 1, to light up LED
jeremycai3721 3:cf5a7230ef4d 66 //
jeremycai3721 3:cf5a7230ef4d 67 // // write 0xAA to MCP23S17 Port A
jeremycai3721 3:cf5a7230ef4d 68 // chip.write(PORT_A, 0xAA);
jeremycai3721 3:cf5a7230ef4d 69 // wait(.5);
jeremycai3721 3:cf5a7230ef4d 70 // // read back value from MCP23S17 Port B and display B0 on mbed led1
jeremycai3721 3:cf5a7230ef4d 71 // led1 = chip.read(PORT_B)& 0x01;
jeremycai3721 3:cf5a7230ef4d 72 // // write 0x55 to MCP23S17 Port A
jeremycai3721 3:cf5a7230ef4d 73 // chip.write(PORT_A, 0x55);
jeremycai3721 3:cf5a7230ef4d 74 // wait(.5);
jeremycai3721 3:cf5a7230ef4d 75 // // read back value from MCP23S17 Port B and display B0 on mbed led1
jeremycai3721 3:cf5a7230ef4d 76 // led1 = chip.read(PORT_B)& 0x01;
jeremycai3721 3:cf5a7230ef4d 77 // // led1 should blink slowly when it is all working
4180_1 0:12f4911d7ba0 78 }
4180_1 0:12f4911d7ba0 79 }