From a0377a315c9dee408508024f329582fc6f93c408 Mon Sep 17 00:00:00 2001
From: Klaus K Wilting <Klaus.K.Wilting@deutschebahn.com>
Date: Thu, 20 Sep 2018 13:23:22 +0200
Subject: [PATCH] gps.cpp, lorawan.cpp: i2c bugfixes (issue #156)

---
 src/gps.cpp       |  5 +----
 src/hal/generic.h |  6 +++++-
 src/lorawan.cpp   | 37 ++++++++++++++++++++++---------------
 3 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/src/gps.cpp b/src/gps.cpp
index 10d05c14..6020434f 100644
--- a/src/gps.cpp
+++ b/src/gps.cpp
@@ -5,7 +5,7 @@
 // Local logging tag
 static const char TAG[] = "main";
 
-TinyGPSPlus gps;        
+TinyGPSPlus gps;
 gpsStatus_t gps_status;
 
 // read GPS data and cast to global struct
@@ -53,7 +53,6 @@ void gps_loop(void *pvParameters) {
       Wire.write(0x00); // dummy write to start read
       Wire.endTransmission();
 
-      Wire.beginTransmission(GPS_ADDR);
       while (cfg.gpsmode) {
         Wire.requestFrom(GPS_ADDR | 0x01, 32);
         while (Wire.available()) {
@@ -61,8 +60,6 @@ void gps_loop(void *pvParameters) {
           vTaskDelay(2 / portTICK_PERIOD_MS); // polling mode: 500ms sleep
         }
       }
-      // after GPS function was disabled, close connect to GPS device
-      Wire.endTransmission();
 
 #endif // GPS Type
     }
diff --git a/src/hal/generic.h b/src/hal/generic.h
index d5863038..f25a8219 100644
--- a/src/hal/generic.h
+++ b/src/hal/generic.h
@@ -35,4 +35,8 @@
 // pin definitions for I2C interface of OLED Display
 #define OLED_RST GPIO_NUM_16 // SSD1306 RST
 #define I2C_SDA GPIO_NUM_4  // SD1306 D1+D2
-#define I2C_SCL GPIO_NUM_15 // SD1306 D0
\ No newline at end of file
+#define I2C_SCL GPIO_NUM_15 // SD1306 D0
+
+// I2C config for Microchip 24AA02E64 DEVEUI unique address
+#define MCP_24AA02E64_I2C_ADDRESS 0x50 // I2C address for the 24AA02E64 
+#define MCP_24AA02E64_MAC_ADDRESS 0xF8 // Memory adress of unique deveui 64 bits
\ No newline at end of file
diff --git a/src/lorawan.cpp b/src/lorawan.cpp
index 5ffed2cb..e7cbcf5e 100644
--- a/src/lorawan.cpp
+++ b/src/lorawan.cpp
@@ -20,6 +20,8 @@ const lmic_pinmap lmic_pins = {.mosi = PIN_SPI_MOSI,
                                .rst = RST,
                                .dio = {DIO0, DIO1, DIO2}};
 
+/* old version
+
 // DevEUI generator using devices's MAC address
 void gen_lora_deveui(uint8_t *pdeveui) {
   uint8_t *p = pdeveui, dmac[6];
@@ -37,13 +39,13 @@ void gen_lora_deveui(uint8_t *pdeveui) {
   }
 }
 
-/* The above function should be changed to this one, but this would be a breaking change
+*/
 
 // DevEUI generator using devices's MAC address
 void gen_lora_deveui(uint8_t *pdeveui) {
   uint8_t *p = pdeveui, dmac[6];
   ESP_ERROR_CHECK(esp_efuse_mac_get_default(dmac));
-   // deveui is LSB, we reverse it so TTN DEVEUI display
+  // deveui is LSB, we reverse it so TTN DEVEUI display
   // will remain the same as MAC address
   // MAC is 6 bytes, devEUI 8, set middle 2 ones
   // to an arbitrary value
@@ -56,7 +58,6 @@ void gen_lora_deveui(uint8_t *pdeveui) {
   *p++ = dmac[1];
   *p++ = dmac[0];
 }
-*/
 
 // Function to do a byte swap in a byte array
 void RevBytes(unsigned char *b, size_t c) {
@@ -98,29 +99,35 @@ void os_getDevEui(u1_t *buf) {
 void get_hard_deveui(uint8_t *pdeveui) {
   // read DEVEUI from Microchip 24AA02E64 2Kb serial eeprom if present
 #ifdef MCP_24AA02E64_I2C_ADDRESS
-  uint8_t i2c_ret;
+
   // Init this just in case, no more to 100KHz
   Wire.begin(I2C_SDA, I2C_SCL, 100000);
   Wire.beginTransmission(MCP_24AA02E64_I2C_ADDRESS);
   Wire.write(MCP_24AA02E64_MAC_ADDRESS);
-  i2c_ret = Wire.endTransmission();
-  // check if device seen on i2c bus
-  if (i2c_ret == 0) {
+
+  // check if device was seen on i2c bus
+  if (Wire.endTransmission() == 0) {
     char deveui[32] = "";
     uint8_t data;
+
     Wire.beginTransmission(MCP_24AA02E64_I2C_ADDRESS);
     Wire.write(MCP_24AA02E64_MAC_ADDRESS);
-    Wire.requestFrom(MCP_24AA02E64_I2C_ADDRESS, 8);
-    while (Wire.available()) {
-      data = Wire.read();
-      sprintf(deveui + strlen(deveui), "%02X ", data);
-      *pdeveui++ = data;
+    Wire.endTransmission();
+
+    if (Wire.requestFrom(MCP_24AA02E64_I2C_ADDRESS, 8)) {
+      while (Wire.available()) {
+        data = Wire.read();
+        sprintf(deveui + strlen(deveui), "%02X ", data);
+        *pdeveui++ = data;
+      }
+      ESP_LOGI(TAG, "Serial EEPROM found, read DEVEUI %s", deveui);
+    } else {
+      ESP_LOGI(TAG, "Could not read DEVEUI from serial EEPROM");
     }
-    i2c_ret = Wire.endTransmission();
-    ESP_LOGI(TAG, "Serial EEPROM 24AA02E64 found, read DEVEUI %s", deveui);
   } else {
-    ESP_LOGI(TAG, "Serial EEPROM 24AA02E64 not found ret=%d", i2c_ret);
+    ESP_LOGI(TAG, "Could not find serial EEPROM on I2C bus");
   }
+
   // Set back to 400KHz to speed up OLED
   Wire.setClock(400000);
 #endif // MCP 24AA02E64