jim hamblen / Mbed 2 deprecated MCP23S17_Basic_IO_Demo

A simple IO demo using the MCP23S17 library

Dependencies:   mbed MCP23S17

Demo for Microchip MCP23S17 16-bit SPI I/O expander chip on mbed LPC1768 using hardware SPI functions. See comments in main.cpp for pin usage. This chip is still available in a DIP package, so it is easy to try on a breadboard. A complete datasheet for the Microchip MCP23SA17 SPI I/O port expander chip can be found at http://ww1.microchip.com/downloads/en/DeviceDoc/20001952c.pdf

Import programMCP23S17_Basic_IO_Demo

A simple IO demo using the MCP23S17 library

Last commit 28 Jan 2011 by jim hamblen

Diff: main.cpp

Revision:
2:934a0500abde
Parent:
1:70e1ebe47253
--- a/main.cpp	Fri Jan 28 01:44:27 2011 +0000
+++ b/main.cpp	Fri Jan 28 02:04:05 2011 +0000
@@ -1,29 +1,34 @@
-/* A simple IO demo using the 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/
-*
+// 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
 
-* MCP23S17 datasheet http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf
-* version 0.4
-*/
 #include "mbed.h"
 #include "MCP23S17.h"
-
+// Create SPI bus
 SPI spi(p5, p6, p7);
-// Create SPI bus
+// 
+// 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 writeOpcode = 0x40;
+char Opcode = 0x40;
 
 // Next create a MCP23S17
 // mbed p20 is connected to ~chipSelect on the MCP23S17
-MCP23S17 chip = MCP23S17(spi, p20, writeOpcode);
+MCP23S17 chip = MCP23S17(spi, p20, Opcode);
 
-// Optional software reset - mbed p20 to MCP23S17 reset pin
-// DigitalOut reset(p20);
+// Optional software reset - mbed p14 to MCP23S17 reset pin
+// DigitalOut reset(p14);
 
 DigitalOut led1(LED1); // mbed LED1 is used for test status display
 
@@ -56,6 +61,6 @@
         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 if it is all working
+        // led1 should blink slowly when it is all working
     }
 }