From 334de50c49317f281d87f44e7b9278e08af19254 Mon Sep 17 00:00:00 2001
From: Perry Hung <iperry@gmail.com>
Date: Mon, 14 Mar 2011 18:37:56 -0400
Subject: Add rudimentary error handling for nack condition

---
 main.cpp | 73 ++++++++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 50 insertions(+), 23 deletions(-)

(limited to 'main.cpp')

diff --git a/main.cpp b/main.cpp
index 7771fa7..db310c0 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,12 +1,13 @@
 // Sample i2c master example for development i2c branch. Writes 0-63 to
 // addresses 0-63 on a 24LC256 EEPROM, then reads them back.
 
+#include <string.h>
 #include "wirish.h"
 #include "i2c.h"
 
 static const uint8 slave_address = 0b1010001;
 
-#define NR_ELEMENTS 4
+#define NR_ELEMENTS 64
 uint8 buf0[NR_ELEMENTS + 2] = {0x0, 0x0};
 uint8 buf1[] = {0x0, 0x0};
 uint8 buf2[NR_ELEMENTS];
@@ -19,12 +20,15 @@ void toggle(void) {
 }
 
 void setup() {
+    uint32 bytes = 1;
     uint32 i;
+    int32 rc = -1;
 
     pinMode(BOARD_LED_PIN, OUTPUT);
-    pinMode(2, OUTPUT);
     Serial2.begin(9600);
     Serial2.println("Hello!");
+
+    pinMode(2, OUTPUT);
     digitalWrite(2, LOW);
 
     for (i = 2; i < sizeof buf0; i++) {
@@ -33,31 +37,54 @@ void setup() {
 
     i2c_master_enable(I2C1, 0);
 
-    /* Write some bytes */
-    msgs[0].addr = slave_address;
-    msgs[0].flags = 0;
-    msgs[0].length = sizeof buf0;
-    msgs[0].data = buf0;
-    i2c_master_xfer(I2C1, msgs, 1);
-    delay(5);
-
+    while (bytes < 64) {
+        Serial2.print("Writing ");
+        Serial2.print(bytes);
+        Serial2.print(" bytes...");
+
+        /* Write test pattern  */
+        msgs[0].addr = slave_address;
+        msgs[0].flags = 0;
+        msgs[0].length = 2+ bytes;
+        msgs[0].data = buf0;
+        i2c_master_xfer(I2C1, msgs, 1);
+        delay(5);
+
+        /* Read it back */
+        msgs[1].addr = slave_address;
+        msgs[1].flags = 0;
+        msgs[1].length = 2;
+        msgs[1].data = buf1;
+        /* Repeated start condition */
+        msgs[2].addr = slave_address;
+        msgs[2].flags = I2C_MSG_READ;
+        msgs[2].length = bytes;
+        msgs[2].data = buf2;
+        i2c_master_xfer(I2C1, msgs + 1, 2);
+
+        /* Compare */
+        rc = memcmp(&buf0[2], buf2, bytes);
+        if (rc == 0) {
+            Serial2.println("good!");
+        } else {
+            Serial2.println("failed!");
+        }
+
+        delay(5);
+        bytes++;
+    }
 }
 
+int32 rc;
+
 void loop() {
-    delay(100);
     toggleLED();
-    /* Write slave address to read */
-    msgs[1].addr = slave_address;
-    msgs[1].flags = 0;
-    msgs[1].length = 2;
-    msgs[1].data = buf1;
-
-    /* Repeated start condition, then read NR_ELEMENTS bytes back */
-    msgs[2].addr = slave_address;
-    msgs[2].flags = I2C_MSG_READ;
-    msgs[2].length = sizeof buf2;
-    msgs[2].data = buf2;
-    i2c_master_xfer(I2C1, msgs + 1, 2);
+    delay(100);
+    rc = i2c_master_xfer(I2C1, msgs + 1, 2);
+    if (rc < 0) {
+        Serial2.println("Failed transfer!");
+        i2c_master_enable(I2C1, 0);
+    }
 }
 
 // Force init to be called *first*, i.e. before static object allocation.
-- 
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