ECE 4180 Labs / Mbed 2 deprecated 4180_Lab1_IOExpandor

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Dependencies:   MCP23S17 mbed

Fork of MCP23S17_Basic_IO_Demo by jim hamblen

Files at this revision

API Documentation at this revision

Revision 3:cf5a7230ef4d, committed 2016-09-25

Comitter:
jeremycai3721
Date:
Sun Sep 25 20:16:55 2016 +0000
Parent:
2:934a0500abde
Commit message:
CodeShare

Changed in this revision

main.cpp Show annotated file Show diff for this revision Revisions of this file 
--- a/main.cpp	Fri Jan 28 02:04:05 2011 +0000
+++ b/main.cpp	Sun Sep 25 20:16:55 2016 +0000
@@ -32,6 +32,8 @@
 
 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.
@@ -51,16 +53,27 @@
 //  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) {
-        // 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 B0 and see if it's 0 (button being pressed)
+        B0 = chip.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
     }
 }