Revision 3:fdb89f47357f, committed 2018-10-16

Comitter:

kzar

Date:

Tue Oct 16 18:55:29 2018 +0000

Parent:

2:934a0500abde

Commit message:

SPI portexpander example code

Changed in this revision

--- a/main.cpp	Fri Jan 28 02:04:05 2011 +0000
+++ b/main.cpp	Tue Oct 16 18:55:29 2018 +0000
@@ -1,19 +1,8 @@
-// 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
-
 #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
@@ -30,37 +19,24 @@
 // Optional software reset - mbed p14 to MCP23S17 reset pin
 // DigitalOut reset(p14);
 
-DigitalOut led1(LED1); // mbed LED1 is used for test status display
 
 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
     chip.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
+    
+   // chip.interruptEnable(PORT_B, 0xFF);
+
+    uint8_t trigger;
     while (1) {
-        // 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
+        //Read in PortB and output it to PortA
+        trigger = chip.read(PORT_B);
+        chip.write(PORT_A, !trigger);
     }
 }