diff --git a/src/utility/linux_kernel/gpio.cpp b/src/utility/linux_kernel/gpio.cpp
index e70b5eb..0ca9e15 100644
--- a/src/utility/linux_kernel/gpio.cpp
+++ b/src/utility/linux_kernel/gpio.cpp
@@ -20,8 +20,8 @@
     #include <unistd.h>    // close()
     #include <fcntl.h>     // open()
     #include <sys/ioctl.h> // ioctl()
-    #include <errno.h>     // errno, strerror()
-    #include <string.h>    // std::string, strcpy()
+    #include <errno.h>     // errno
+    #include <string.h>    // strerror(), memset(), strcpy()
     #include <map>
     #include "linux/gpio.h"
     #include "gpio.h"
diff --git a/src/utility/linux_kernel/gpio.h b/src/utility/linux_kernel/gpio.h
index 4f64fd0..f04ef1c 100644
--- a/src/utility/linux_kernel/gpio.h
+++ b/src/utility/linux_kernel/gpio.h
@@ -20,8 +20,8 @@
 #define CIRQUEPINNACLE_UTILITY_LINUX_KERNEL_GPIO_H_
 #ifndef ARDUINO
 
-    #include <stdexcept>
-    #include <cstdint>
+    #include <cstdint>      // uintXX_t
+    #include <stdexcept>    // std::exception, std::string
     #include "linux/gpio.h" // gpiochip_info
 
     #ifdef __cplusplus
diff --git a/src/utility/linux_kernel/i2c.cpp b/src/utility/linux_kernel/i2c.cpp
index 0e0093d..b4138cb 100644
--- a/src/utility/linux_kernel/i2c.cpp
+++ b/src/utility/linux_kernel/i2c.cpp
@@ -18,11 +18,15 @@
  */
 #ifndef ARDUINO
 
-    #include <stdlib.h>
-    #include <stdio.h>
-    #include <fcntl.h>
-    #include <unistd.h>
-    #include <sys/ioctl.h>
+    #include <stdlib.h>    // free(), malloc()
+    #include <stddef.h>    // size_t
+    #include <stdint.h>    // uintXX_t
+    #include <stdio.h>     // sprintf
+    #include <unistd.h>    // close()
+    #include <fcntl.h>     // open()
+    #include <sys/ioctl.h> // ioctl()
+    #include <errno.h>     // errno
+    #include <string.h>    // strerror()
     #include <linux/i2c.h>
     #include <linux/i2c-dev.h>
     #include "i2c.h"
@@ -51,7 +55,9 @@ namespace cirque_pinnacle_arduino_wrappers {
         sprintf(filename, "/dev/i2c-%d", busNumber);
         file = open(filename, O_RDWR);
         if (file < 0) {
-            throw I2CException("Can't open I2C bus. Check access rights.");
+            std::string msg = "[TwoWire::begin] Can't open I2C bus; ";
+            msg += strerror(errno);
+            throw I2CException(msg);
         }
         bus_fd = file;
     }
@@ -65,7 +71,9 @@ namespace cirque_pinnacle_arduino_wrappers {
     void TwoWire::beginTransmission(uint8_t address)
     {
         if (ioctl(bus_fd, I2C_SLAVE, address) < 0) {
-            throw I2CException("Could not select I2C slave address.");
+            std::string msg = "[TwoWire::beginTransmission] Could not select I2C slave address; ";
+            msg += strerror(errno);
+            throw I2CException(msg);
         }
         xBuffIndex = 0;
         xBuffLen = 0;
@@ -76,7 +84,9 @@ namespace cirque_pinnacle_arduino_wrappers {
         (void)sendStop; // param not used in this implementation
 
         if (::write(bus_fd, xBuff, xBuffLen) != xBuffLen) {
-            throw I2CException("Could not write data to I2C bus.");
+            std::string msg = "[TwoWire::endTransmission] Could not write data to I2C bus; ";
+            msg += strerror(errno);
+            throw I2CException(msg);
         }
         return xBuffLen;
     }
@@ -102,7 +112,9 @@ namespace cirque_pinnacle_arduino_wrappers {
         xBuffIndex = 0;
         int retVal = ::read(bus_fd, xBuff, quantity);
         if (retVal < 0) {
-            throw I2CException("Could not read data from I2C bus.");
+            std::string msg = "[TwoWire::endTransmission] Could not read data from I2C bus; ";
+            msg += strerror(errno);
+            throw I2CException(msg);
         }
         xBuffLen = quantity;
         return xBuffLen;
diff --git a/src/utility/linux_kernel/i2c.h b/src/utility/linux_kernel/i2c.h
index fcbfa57..14139aa 100644
--- a/src/utility/linux_kernel/i2c.h
+++ b/src/utility/linux_kernel/i2c.h
@@ -20,8 +20,8 @@
 #define CIRQUEPINNACLE_UTILITY_LINUX_KERNEL_I2C_H_
 #ifndef ARDUINO
 
-    #include <cstdint>
-    #include <stdexcept>
+    #include <cstdint>   // uintXX_t
+    #include <stdexcept> // std::exception, std::string
 
     #ifdef __cplusplus
 extern "C" {
diff --git a/src/utility/linux_kernel/spi.cpp b/src/utility/linux_kernel/spi.cpp
index efc2dc7..b82aed5 100644
--- a/src/utility/linux_kernel/spi.cpp
+++ b/src/utility/linux_kernel/spi.cpp
@@ -17,13 +17,13 @@
  * SOFTWARE.
  */
 #ifndef ARDUINO
-    #include <fcntl.h>
+    #include <stdint.h>    // uintXX_ts
+    #include <unistd.h>    // close()
+    #include <fcntl.h>     // open()
+    #include <sys/ioctl.h> // ioctl()
+    #include <errno.h>     // errno,
+    #include <string.h>    // memset() strerror()
     #include <linux/spi/spidev.h>
-    #include <memory.h>
-    #include <stdio.h>
-    #include <stdlib.h>
-    #include <sys/ioctl.h>
-    #include <unistd.h>
     #include "spi.h"
 
     #ifdef __cplusplus
@@ -61,7 +61,11 @@ namespace cirque_pinnacle_arduino_wrappers {
 
         fd = open(device, O_RDWR);
         if (fd < 0) {
-            throw SPIException("can't open device");
+            std::string msg = "[SPIClass::begin] Could not open device ";
+            msg += device;
+            msg += "; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
         spiIsInitialized = true;
 
@@ -70,35 +74,47 @@ namespace cirque_pinnacle_arduino_wrappers {
         // spi mode
         ret = ioctl(fd, SPI_IOC_WR_MODE, &settings.mode);
         if (ret == -1) {
-            throw SPIException("SPI can't set mode");
+            std::string msg = "[SPIClass::begin] Could not set write mode; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
 
         ret = ioctl(fd, SPI_IOC_RD_MODE, &settings.mode);
         if (ret == -1) {
-            throw SPIException("SPI can't read mode");
+            std::string msg = "[SPIClass::begin] Could not set read mode; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
 
         // bits per word
         uint8_t bits = PINNACLE_SPI_BITS_PER_WORD;
         ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
         if (ret == -1) {
-            throw SPIException("SPI can't set bits per word");
+            std::string msg = "[SPIClass::begin] Could not set write bits per word; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
 
         ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
         if (ret == -1) {
-            throw SPIException("SPI can't read bits per word");
+            std::string msg = "[SPIClass::begin] Could not set read bits per word; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
 
         // max speed Hz
         ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &settings.clock);
         if (ret == -1) {
-            throw SPIException("SPI can't set max speed Hz");
+            std::string msg = "[SPIClass::begin] Could not set write max speed Hz; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
 
         ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &settings.clock);
         if (ret == -1) {
-            throw SPIException("SPI can't read max speed Hz");
+            std::string msg = "[SPIClass::begin] Could not set read max speed Hz; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
 
         _spi_speed = settings.clock;
@@ -120,7 +136,9 @@ namespace cirque_pinnacle_arduino_wrappers {
         int ret;
         ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
         if (ret < 1) {
-            throw SPIException("SPI ioctl() transfer failed.");
+            std::string msg = "[SPIClass::transfer(tx)] Could not transfer buffer; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
         return rx;
     }
@@ -140,7 +158,9 @@ namespace cirque_pinnacle_arduino_wrappers {
         int ret;
         ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
         if (ret < 1) {
-            throw SPIException("SPI ioctl() transfer failed.");
+            std::string msg = "[SPIClass::transfer(tx, rx, len)] Could not transfer buffer; ";
+            msg += strerror(errno);
+            throw SPIException(msg);
         }
     }
 
diff --git a/src/utility/linux_kernel/spi.h b/src/utility/linux_kernel/spi.h
index 3bb2991..573c6c5 100644
--- a/src/utility/linux_kernel/spi.h
+++ b/src/utility/linux_kernel/spi.h
@@ -20,8 +20,8 @@
 #define CIRQUEPINNACLE_UTILITY_LINUX_KERNEL_SPI_H_
 #ifndef ARDUINO
 
-    #include <cstdint>
-    #include <stdexcept>
+    #include <cstdint>   // uintXX_t
+    #include <stdexcept> // std::exception, std::string
     #include <linux/spi/spidev.h>
 
     #ifdef __cplusplus