Zhen Liu / Mbed 2 deprecated HW1_extraE

Extra problem 5 for HW 1

Dependencies:   MCP23S17 mbed

Fork of MCP23S17_Basic_IO_Demo by jim hamblen

main.cpp@3:07745b21792d, 2015-02-18 (annotated)

Committer:
lzzcd001
Date:
Wed Feb 18 14:49:26 2015 +0000
Revision:
3:07745b21792d
Parent:
2:934a0500abde 
Extra problem 5 for HW 1

Who changed what in which revision?

UserRevisionLine numberNew contents of line
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);
lzzcd001 3:07745b21792d 16 DigitalOut a(p21);
lzzcd001 3:07745b21792d 17
4180_1 2:934a0500abde 18 //
4180_1 2:934a0500abde 19 // Wiring Connections:
4180_1 0:12f4911d7ba0 20 // mbed p5,p6,p7 are tied to MCP23S17 SI, SO, SCK pins
4180_1 2:934a0500abde 21 // mbed p20 to MCP23S17 CS
4180_1 2:934a0500abde 22 // MCP23S17 reset pin pulled high
4180_1 2:934a0500abde 23 // MCP23S17 GPA0 connected to GPB0 for loopback test
4180_1 0:12f4911d7ba0 24 // 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 25 // This is referred to as the opcode in the device datasheet
4180_1 2:934a0500abde 26 char Opcode = 0x40;
lzzcd001 3:07745b21792d 27 char OpcodeIn = 0x42;
4180_1 0:12f4911d7ba0 28
4180_1 0:12f4911d7ba0 29 // Next create a MCP23S17
4180_1 0:12f4911d7ba0 30 // mbed p20 is connected to ~chipSelect on the MCP23S17
4180_1 2:934a0500abde 31 MCP23S17 chip = MCP23S17(spi, p20, Opcode);
lzzcd001 3:07745b21792d 32 MCP23S17 chip2 = MCP23S17(spi, p20, OpcodeIn);
4180_1 0:12f4911d7ba0 33
4180_1 2:934a0500abde 34 // Optional software reset - mbed p14 to MCP23S17 reset pin
4180_1 2:934a0500abde 35 // DigitalOut reset(p14);
4180_1 1:70e1ebe47253 36
4180_1 0:12f4911d7ba0 37 DigitalOut led1(LED1); // mbed LED1 is used for test status display
4180_1 0:12f4911d7ba0 38
4180_1 0:12f4911d7ba0 39 int main() {
lzzcd001 3:07745b21792d 40 a = 1;
4180_1 1:70e1ebe47253 41 // The MCP23S17 reset pin can just be pulled high, since it has a power on reset circuit.
4180_1 1:70e1ebe47253 42 // The reset pin can be used for a software forced reset by pulling it low with an mbed GPIO pin.
4180_1 1:70e1ebe47253 43 // But just leave it pulled high for this simple demo code.
4180_1 0:12f4911d7ba0 44 // After a power on reset, both IO ports default to input mode
4180_1 0:12f4911d7ba0 45 //
4180_1 1:70e1ebe47253 46 // Here is the optional code for a software reset
4180_1 1:70e1ebe47253 47 // reset = 0;
4180_1 1:70e1ebe47253 48 // wait_us(1);
4180_1 1:70e1ebe47253 49 // reset = 1;
4180_1 1:70e1ebe47253 50 //
4180_1 0:12f4911d7ba0 51 // Set all 8 Port A bits to output direction
4180_1 0:12f4911d7ba0 52 chip.direction(PORT_A, 0x00);
4180_1 0:12f4911d7ba0 53 // Set all 8 Port B bits to input direction
4180_1 0:12f4911d7ba0 54 chip.direction(PORT_B, 0xFF);
lzzcd001 3:07745b21792d 55 chip2.direction(PORT_A, 0x00);
lzzcd001 3:07745b21792d 56 chip2.direction(PORT_B, 0xFF);
4180_1 0:12f4911d7ba0 57 led1=0;
lzzcd001 3:07745b21792d 58 int mid = 0;
4180_1 0:12f4911d7ba0 59 // Start Loopback test sending out and reading back values
4180_1 0:12f4911d7ba0 60 // loopback test uses A0 and B0 pins - so use a wire to jumper those two pins on MCP23S17 together
4180_1 0:12f4911d7ba0 61 while (1) {
4180_1 0:12f4911d7ba0 62 // write 0xAA to MCP23S17 Port A
lzzcd001 3:07745b21792d 63 mid = chip.read(PORT_B) & 0x01;
lzzcd001 3:07745b21792d 64 wait(.1);
lzzcd001 3:07745b21792d 65 chip.write(PORT_A, mid);
4180_1 0:12f4911d7ba0 66 // read back value from MCP23S17 Port B and display B0 on mbed led1
lzzcd001 3:07745b21792d 67 wait(.1);
lzzcd001 3:07745b21792d 68 mid = chip2.read(PORT_B);
lzzcd001 3:07745b21792d 69 wait(.1);
4180_1 0:12f4911d7ba0 70 // write 0x55 to MCP23S17 Port A
lzzcd001 3:07745b21792d 71 chip2.write(PORT_A, mid);
lzzcd001 3:07745b21792d 72 wait(.1);
4180_1 2:934a0500abde 73 // led1 should blink slowly when it is all working
4180_1 0:12f4911d7ba0 74 }
4180_1 0:12f4911d7ba0 75 }