Diff: main.cpp

Revision:

2:2e8fca65efaf

Parent:

1:d7fe22a24841

Child:

3:8f437a811ecf

--- a/main.cpp	Sat Aug 21 16:51:33 2010 +0000
+++ b/main.cpp	Sun Aug 22 15:39:32 2010 +0000
@@ -1,54 +1,165 @@
 /* Test drive 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/
+*
+* NB this code is inteded to test the driver library, not the chip
+* which is assumed to work as specified
+* MCP23S17 datasheet http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf
+* version 0.2
 */
+
 #include "mbed.h"
 #include "MCP23S17.h"
 
 SPI spi(p5, p6, p7);
 
-char writeOpcode = 0x40; // A0, A1, A2 are tied to ground on the breadboard.
-MCP23S17 chip = MCP23S17(spi, p20, 0x40);
-DigitalInOut chipA0(p12);
-DigitalInOut  chipB0(p10);
+// 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;
+// mbed pin20 is connected to ~chipSelect of the MCP23S17
+MCP23S17 chip = MCP23S17(spi, p20, writeOpcode); // create MCP23S17
+DigitalOut    chipNotReset(p14); // connected to ~reset of the MCP23S17
+DigitalInOut chipA0(p12);  // connected to Port A bit 0 of the MCP23S17
+DigitalInOut  chipB0(p10); // connected to Port B bit 0 of the MCP23S17
+DigitalIn   chipIntA(p16); // connected to INTA on the MCP23S17
+DigitalIn   chipIntB(p18); // connected to INTB on the MCP23S17
 
-void checkEqual(int expected, int actual, char * text) {
+void reset() {
+    // I'm not sure we need the delays, but better safe than sorry.
+    chipNotReset = 0;  // reset chip
+    wait_us(10);
+    chipNotReset = 1;
+    wait_us(10);
+}
+
+void checkEqual(int expected, int actual, char * description) {
     if (expected != actual) {
-        printf("%s **TEST FAILED** - expected %i but get %i\r\n", text, expected, actual);
+        printf("%s **TEST FAILED** - expected %i but get %i\r\n", description, expected, actual);
         exit(-1);
     }
 }
 
-int main() {
+void testInputFromPortA() {
+    reset();
+    chipA0.output(); // prepare to output from the mbed
+    chip.directionA(0x01); // chip Port A bit 0 set to input
+    chipA0 = 0;
+    checkEqual(0, chip.inputA() && 0x1,"read from A0");
+    chipA0 = 1;
+    checkEqual(1, chip.inputA() && 0x1,"read from A0");
+}
+
+void testInputFromPortB() {
+    reset();
+    chipB0.output(); // output from the mbed
+    chip.directionB(0x01); //  bit 0 set to input
+    chipB0 = 0;
+    checkEqual(0, chip.inputB() && 0x1,"read from B0");
+    chipB0 = 1;
+    checkEqual(1, chip.inputB() && 0x1,"read from B0");
+}
+
+void testOutputToPortA() {
+    reset();
+    chipA0.input(); // input to the mbed
+    chip.directionA(0xFE); //  bit 0 set to output
+    chip.outputA(0x00);
+    checkEqual(0, int(chipA0),"write to A0");
+    chip.outputA(0x01);
+    checkEqual(1, int(chipA0),"write to A0");
+}
+
+void testOutputToPortB() {
+    reset();
+    chipB0.input(); // input to the mbed
+    chip.directionB(0xFE); //  bit 0 set to output
+    chip.outputB(0x00);
+    checkEqual(0, int(chipB0),"write to B0");
+    chip.outputB(0x01);
+    checkEqual(1, int(chipB0),"write to B0");
+}
+
+void testInterruptEnableOnPortA() {
+// NB by default both int pins are Active-LOW
+    reset();
     chipA0.output(); // output from the mbed
-    chipB0.input();   // input to the mbed
-    for (int i = 0; i < 100; i++) {
-        chip.directionA(0xFF); // all 8 bits set to input
-        chip.directionB(0xFE); // bit 0 set to output
-        chipA0 = 1;
-        // copy input bit 0 from A to output bit 0 on B
-        chip.outputB(chip.inputA() && 1);
-        checkEqual(1, int(chipB0),"copying 1 from A0 to B0");
-        // copy input bit 0 from A to output bit 0 on B
-        chipA0 = 0;
-        chip.outputB(chip.inputA() && 1);
-        checkEqual(0, int(chipB0), "copying 0 from A0 to B0");
-    }
-    
+    chip.directionA(0x01); //  bit 0 set to input
+    chipA0 = 1;
+    checkEqual(1, int(chipIntA),"interrupts not yet enabled");
+    chipA0 = 0;
+    chip.interruptEnableA(0x01); // interupt enabled on pin 0
+    checkEqual(1, int(chipIntA), "value has not changed");
+    chipA0 = 1;
+    wait_us(1); // test fails without this - mbed is too darned fast!
+    checkEqual(0, int(chipIntA), "value has changed");
+}
+
+void testInterruptEnableOnPortB() {
+// NB by default both int pins are Active-LOW
+    reset();
+    chipB0.output(); // output from the mbed
+    chip.directionB(0x01); //  bit 0 set to input
+    chipB0 = 1;
+    chip.interruptEnableB(0x01); // interupt enabled on pin 0
+    wait_us(1); 
+    checkEqual(0, int(chipIntB), "interruptB");
+}
+
+void testMirrorInterrupts() {
+    reset();
     chipB0.output(); // output from the mbed
-    chipA0.input();   // input to the mbed
-     for (int i = 0; i < 100; i++) {
-        chip.directionB(0xFF); // all 8 bits set to input
-        chip.directionA(0xFE); // bit 0 set to output
-        chipB0 = 1;
-        // copy input bit 0 from B to output bit 0 on A
-        chip.outputA(chip.inputB() && 1);
-        checkEqual(1, int(chipB0),"copying 1 from B0 to A0");
-        // copy input bit 0 from B to output bit 0 on A
-        chipB0 = 0;
-        chip.outputA(chip.inputB() && 1);
-        checkEqual(0, int(chipB0), "copying 0 from B0 to A0");
-    }
-    
+    chip.directionB(0x01); //  bit 0 set to input
+    chipB0 = 1;
+    chip.interruptEnableB(0x01); // interupt enabled on pin 0
+    wait_us(1); 
+    checkEqual(0, int(chipIntB), "interruptB");
+    checkEqual(1, int(chipIntA), "before mirroring"); // no interrupt A yet
+    chip.mirrorInterrupts(true);
+    wait_us(1); 
+    checkEqual(0, int(chipIntA), "after mirroring");
+    chip.mirrorInterrupts(false);
+    wait_us(1); 
+    checkEqual(1, int(chipIntA), "after mirroring turned off");
+}
+
+void testInterruptPolarity() {
+// NB by default both int pins are Active-LOW
+// interrupt off (so LHIGH) after POR
+    reset();
+    checkEqual(1, int(chipIntA),"interrupt ACTIVE_LOW by default");
+    chip.interruptPolarity(ACTIVE_HIGH);
+    wait_us(1);
+    checkEqual(0, int(chipIntA), "interrupt ACTIVE_HIGH");
+    chip.interruptPolarity(ACTIVE_LOW);
+    wait_us(1);
+    checkEqual(1, int(chipIntA), "interrupt ACTIVE_LOW");
 }
+
+void testInterruptControlAndDefaultValueOnPortA() {
+     reset();
+     chipA0.output(); // output from the mbed
+     chip.directionA(0x01); //  bit 0 set to input
+     chipA0 = 0;
+     checkEqual(1, int(chipIntA),"interrupt ACTIVE_LOW by default");
+     chip.interruptEnableA(0x01); // interupt enabled on pin 0
+     chip.defaultValueA(0x01); // default value != input value
+     checkEqual(1, int(chipIntA),"still no interrupt"); // interrupt control still set to interrupt on change
+     chip.interruptControlA(0x01);
+     wait_us(1);
+     checkEqual(0, int(chipIntA), "expecting interrupt as default != input");
+}
+
+int main() {
+    testInputFromPortA();
+    testInputFromPortB();
+    testOutputToPortA();
+    testOutputToPortB();
+    testInterruptEnableOnPortA();
+    testInterruptEnableOnPortB();
+    testInterruptPolarity();
+    testMirrorInterrupts();
+    testInterruptControlAndDefaultValueOnPortA();
+    printf("all tests OK\r\n");
+}