GoPiGo3 C++ API Fixes for https://github.com/DexterInd/GoPiGo3/issues/369, plus README and clean utility

Software/C/GoPiGo3.cpp

@@ -571,7 +571,7 @@ int GoPiGo3::get_motor_encoder(uint8_t port, int32_t &value){
   }
   uint32_t Value;
   int res = spi_read_32(msg_type, Value);
-  value = (int)(Value / MOTOR_TICKS_PER_DEGREE);
+  value = (int32_t)(Value) / MOTOR_TICKS_PER_DEGREE;
   return res;
 }
 

Software/C/GoPiGo3.h

@@ -49,13 +49,13 @@
 #define ERROR_GROVE_TYPE_MISMATCH  -6
 #define ERROR_GROVE_DATA_ERROR     -7
 
-int spi_file_handle = -1;                    // SPI file handle
-struct spi_ioc_transfer spi_xfer_struct;     // SPI transfer struct
-uint8_t spi_array_out[LONGEST_SPI_TRANSFER]; // SPI out array
-uint8_t spi_array_in[LONGEST_SPI_TRANSFER];  // SPI in array
+static int spi_file_handle = -1;                    // SPI file handle
+static struct spi_ioc_transfer spi_xfer_struct;     // SPI transfer struct
+static uint8_t spi_array_out[LONGEST_SPI_TRANSFER]; // SPI out array
+static uint8_t spi_array_in[LONGEST_SPI_TRANSFER];  // SPI in array
 
 // Set up SPI. Open the file, and define the configuration.
-int spi_setup(){
+static int spi_setup(){
   spi_file_handle = open(SPIDEV_FILE_NAME, O_RDWR);
 
   if (spi_file_handle < 0){
@@ -71,7 +71,7 @@ int spi_setup(){
 }
 
 // Transfer length number of bytes. Write from outArray, read to inArray.
-int spi_transfer_array(uint8_t length, uint8_t *outArray, uint8_t *inArray){
+static int spi_transfer_array(uint8_t length, uint8_t *outArray, uint8_t *inArray){
   spi_xfer_struct.len = length;
   spi_xfer_struct.tx_buf = (unsigned long)outArray;
   spi_xfer_struct.rx_buf = (unsigned long)inArray;
@@ -84,13 +84,13 @@ int spi_transfer_array(uint8_t length, uint8_t *outArray, uint8_t *inArray){
 }
 
 // Function to call if an error occured that can not be resolved, such as failure to set up SPI
-void fatal_error(const char *error){
+static void fatal_error(const char *error){
   throw std::runtime_error(error);
 }
 
 //struct timespec _time;
-struct timeval _time;
-double get_time(){
+static struct timeval _time;
+static double get_time(){
   //clock_gettime(CLOCK_MONOTONIC_RAW, &_time);
   gettimeofday(&_time, NULL);
   return _time.tv_sec + (_time.tv_usec / 1000000);
@@ -252,8 +252,8 @@ class GoPiGo3{
     float WHEEL_BASE_CIRCUMFERENCE = WHEEL_BASE_WIDTH * M_PI;  // pi from cmath
     float WHEEL_CIRCUMFERENCE      = WHEEL_DIAMETER   * M_PI;  // pi from cmath
     int   MOTOR_GEAR_RATIO         = 120;
-    int   ENCODER_TICKS_PER_ROTATION = 6;  // default GoPiGo3 has 6 ticks, 16 ticks if in .list_of_serial_numbers.pkl file
-    int   MOTOR_TICKS_PER_DEGREE     = ((MOTOR_GEAR_RATIO * ENCODER_TICKS_PER_ROTATION) / 360.0);  // ticks per degree of wheel shaft rotation
+    int   ENCODER_TICKS_PER_ROTATION = 6;  // default GoPiGo3 has 6 ticks, 16 ticks if in .gpg3_list_of_serial_numbers.pkl file
+    float MOTOR_TICKS_PER_DEGREE     = ((MOTOR_GEAR_RATIO * ENCODER_TICKS_PER_ROTATION) / 360.0);  // ticks per degree of wheel shaft rotation
 
   // Confirm that the BrickPi3 is connected and up-to-date
     int     detect(bool critical = true);

Software/C/README.md

@@ -0,0 +1,77 @@
+# C++ programs for GoPiGo3
+
+The C++ GoPiGo3 API is defined by the files:  
+
+```
+GoPiGo3.h
+GoPiGo3.cpp
+```
+
+and libgopigo3.so is the built link library for the API.  
+
+Examples/ contains C++ programs that use the C++ GoPiGo3 API:  
+
+```
+info          Read GoPiGo3 Board Info  
+vbatt         Read the GoPiGo3 battery voltage  
+leds          Flash GoPiGo3 red LEDs  
+drive         Use keyboard to drive your GoPiGo3  
+servos        Rotate servos through range  
+grove_led     Blink Grove LED  
+sensors       Use Grove Ultrasonic and IR Receiver  
+i2c           Drive PCA9570 I2C Expander  
+motors        Gently spin left wheel forward,
+                    watch encoder values, right wheel turn
+```
+
+
+
+### To build
+
+1) install cmake:  
+
+```
+  sudo apt-get install cmake
+```
+2) run cmake to build make files  
+
+```
+  cmake CMakeLists.txt
+```
+
+5) run make to build the examples and the libgopigo3.so link library  
+
+```
+  make
+```
+
+6) try out the info executable:  
+
+```
+   ./info
+```
+
+7) Try out the other executables 
+
+
+NOTE:  To clean the folder of all build products and binaries  
+
+```
+   ./clean.sh
+```
+
+
+==============  
+
+NOTE:  To try your hand with the C++ GoPiGo3 API:
+
+```
+mkdir test
+cd test
+(create myrobot.cpp, and reference the the API with #include GoPiGo3.h)
+g++ -o myrobot myrobot.cpp ../GoPiGo3.cpp -I..
+./myrobot
+```
+
+The executable will be in the same folder as your C++ program (test/).  
+

Software/C/clean.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# FILE:  clean.sh
+
+# Use to fully clean out all cmake and make products (restore to original contents)
+
+echo -e "Removing all built executables"
+make clean
+echo -e "Removing all cmake generated files"
+rm CMakeCache.txt
+rm -rf CMakeFiles
+rm *.cmake
+rm Makefile
+echo -e "See README.txt for build instructions"
+
+