ECE 4180 Labs
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4180_Lab1_IOExpandor_XC
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Fork of MCP23S17_Basic_IO_Demo by
main.cpp
- Committer:
- jeremycai3721
- Date:
- 2016-09-25
- Revision:
- 3:ff23f7e9c064
- Parent:
- 2:934a0500abde
File content as of revision 3:ff23f7e9c064:
// A simple IO demo using the MCP23S17 library // // MCP23S17 Library Copyright (c) 2010 Romilly Cocking // Released under the MIT License: http://mbed.org/license/mit // // See http://mbed.org/users/romilly/notebook/mcp23s17-addressable-16-bit-io-expander-with-spi/ // // // MCP23S17 datasheet http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf // uses MCP23S17 library version 0.4 // Extra Credit // Chip 2 is used to read in pushbutton data on // CS "Chip Select" for chip2 is P19 // Chip 2 reads Pushbutton input from B0 // Chip 1 outputs LED high on A0 #include "mbed.h" #include "MCP23S17.h" // Create SPI bus SPI spi(p5, p6, p7); // // Wiring Connections: // mbed p5,p6,p7 are tied to MCP23S17 SI, SO, SCK pins // mbed p20 to MCP23S17 CS // MCP23S17 reset pin pulled high // MCP23S17 GPA0 connected to GPB0 for loopback test // A0, A1, A2 of the MCP23S17 are tied to ground on the breadboard, so the 8-bit address for writes is 0x40 // This is referred to as the opcode in the device datasheet char Opcode = 0x40; // Next create a MCP23S17 // mbed p20 is connected to ~chipSelect on the MCP23S17 MCP23S17 chip = MCP23S17(spi, p20, Opcode); // Chip 2 instance // CS pin (chip select) is P19 on mbed MCP23S17 chip2 = MCP23S17(spi, p19, Opcode); // Optional software reset - mbed p14 to MCP23S17 reset pin // DigitalOut reset(p14); DigitalOut led1(LED1); // mbed LED1 is used for test status display int B0; int main() { // The MCP23S17 reset pin can just be pulled high, since it has a power on reset circuit. // The reset pin can be used for a software forced reset by pulling it low with an mbed GPIO pin. // But just leave it pulled high for this simple demo code. // After a power on reset, both IO ports default to input mode // // Here is the optional code for a software reset // reset = 0; // wait_us(1); // reset = 1; // // Set all 8 Port A bits to output direction chip.direction(PORT_A, 0x00); // Set all 8 Port B bits to input direction chip2.direction(PORT_B, 0xFF); led1=0; // Start Loopback test sending out and reading back values // loopback test uses A0 and B0 pins - so use a wire to jumper those two pins on MCP23S17 together while (1) { // read in B0 and see if it's 0 (button being pressed) B0 = chip2.read(PORT_B)& 0x01; if (B0 == 0) { chip.write(PORT_A,1); // output 1 at A0 to light up LED } else { chip.write(PORT_A,0); // turn off LED } // if yes, out put Port A0 to 1, to light up LED // // // write 0xAA to MCP23S17 Port A // chip.write(PORT_A, 0xAA); // wait(.5); // // read back value from MCP23S17 Port B and display B0 on mbed led1 // led1 = chip.read(PORT_B)& 0x01; // // write 0x55 to MCP23S17 Port A // chip.write(PORT_A, 0x55); // wait(.5); // // read back value from MCP23S17 Port B and display B0 on mbed led1 // led1 = chip.read(PORT_B)& 0x01; // // led1 should blink slowly when it is all working } }