Revision 3:ff23f7e9c064, committed 2016-09-25

Comitter:

jeremycai3721

Date:

Sun Sep 25 20:18:06 2016 +0000

Parent:

2:934a0500abde

Commit message:

CodeShare

Changed in this revision

--- a/main.cpp	Fri Jan 28 02:04:05 2011 +0000
+++ b/main.cpp	Sun Sep 25 20:18:06 2016 +0000
@@ -9,6 +9,15 @@
 // 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
@@ -27,11 +36,17 @@
 // 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.
@@ -46,21 +61,32 @@
 //  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);
+    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) {
-        // 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 = 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
     }
 }