diff --git a/SampleProjects/TestSomething/test/defines.cpp b/SampleProjects/TestSomething/test/defines.cpp
index 6b09d851..c0f43344 100644
--- a/SampleProjects/TestSomething/test/defines.cpp
+++ b/SampleProjects/TestSomething/test/defines.cpp
@@ -8,4 +8,26 @@ unittest(binary)
   assertEqual(100, B1100100);
 }
 
+#ifdef __AVR__
+#define DDRE      _SFR_IO8(0x02)
+
+ unittest(SFR_IO8)
+ {
+   // in normal arduino code, you can do this.  in arduino_ci, you might get an
+   // error like: cannot take the address of an rvalue of type 'int'
+   //
+   // this tests that directly
+   auto foo = &DDRE;  // avoid compiler warning by using the result of an expression
+ }
+
+unittest(read_write)
+{
+  _SFR_IO8(1) = 0x11;
+  _SFR_IO8(2) = 0x22;
+  assertEqual((int) 0x11, (int) _SFR_IO8(1));
+  assertEqual((int) 0x22, (int) _SFR_IO8(2));
+  assertEqual((int) 0x2211, (int) _SFR_IO16(1));
+}
+#endif
+
 unittest_main()
diff --git a/SampleProjects/TestSomething/test/godmode.cpp b/SampleProjects/TestSomething/test/godmode.cpp
index e6c69502..d9ab6716 100644
--- a/SampleProjects/TestSomething/test/godmode.cpp
+++ b/SampleProjects/TestSomething/test/godmode.cpp
@@ -175,18 +175,35 @@ unittest(spi) {
   // 8-bit
   state->reset();
   state->spi.dataIn = "LMNO";
+  SPI.beginTransaction(SPISettings(14000000, LSBFIRST, SPI_MODE0));
   uint8_t out8 = SPI.transfer('a');
+  SPI.endTransaction();
   assertEqual("a", state->spi.dataOut);
   assertEqual('L', out8);
   assertEqual("MNO", state->spi.dataIn);
 
-  // 16-bit
+  // 16-bit MSBFIRST
   union { uint16_t val; struct { char lsb; char msb; }; } in16, out16;
   state->reset();
   state->spi.dataIn = "LMNO";
   in16.lsb = 'a';
   in16.msb = 'b';
+  SPI.beginTransaction(SPISettings(14000000, MSBFIRST, SPI_MODE0));
   out16.val = SPI.transfer16(in16.val);
+  SPI.endTransaction();
+  assertEqual("NO", state->spi.dataIn);
+  assertEqual('M', out16.lsb);
+  assertEqual('L', out16.msb);
+  assertEqual("ba", state->spi.dataOut);
+
+  // 16-bit LSBFIRST
+  state->reset();
+  state->spi.dataIn = "LMNO";
+  in16.lsb = 'a';
+  in16.msb = 'b';
+  SPI.beginTransaction(SPISettings(14000000, LSBFIRST, SPI_MODE0));
+  out16.val = SPI.transfer16(in16.val);
+  SPI.endTransaction();
   assertEqual("NO", state->spi.dataIn);
   assertEqual('L', out16.lsb);
   assertEqual('M', out16.msb);
@@ -196,7 +213,9 @@ unittest(spi) {
   state->reset();
   state->spi.dataIn = "LMNOP";
   char inBuf[6] = "abcde";
+  SPI.beginTransaction(SPISettings(14000000, LSBFIRST, SPI_MODE0));
   SPI.transfer(inBuf, 4);
+  SPI.endTransaction();
 
   assertEqual("abcd", state->spi.dataOut);
   assertEqual("LMNOe", String(inBuf));
diff --git a/cpp/arduino/Godmode.cpp b/cpp/arduino/Godmode.cpp
index 102afca6..36f44cfd 100644
--- a/cpp/arduino/Godmode.cpp
+++ b/cpp/arduino/Godmode.cpp
@@ -113,3 +113,5 @@ SPIClass SPI = SPIClass(&GODMODE()->spi.dataIn, &GODMODE()->spi.dataOut);
 
 // defined in Wire.h
 TwoWire Wire = TwoWire();
+
+volatile uint8_t __ARDUINO_CI_SFR_MOCK[1024];
diff --git a/cpp/arduino/SPI.h b/cpp/arduino/SPI.h
index f10cd201..15cfdf31 100644
--- a/cpp/arduino/SPI.h
+++ b/cpp/arduino/SPI.h
@@ -40,7 +40,10 @@
 
 class SPISettings {
 public:
-  SPISettings(uint32_t clock, uint8_t bitOrder, uint8_t dataMode){};
+  uint8_t bitOrder;
+  SPISettings(uint32_t clock, uint8_t bitOrder = MSBFIRST, uint8_t dataMode = SPI_MODE0){
+    this->bitOrder = bitOrder;
+  };
   SPISettings(){};
 };
 
@@ -68,6 +71,7 @@ class SPIClass: public ObservableDataStream {
   // and configure the correct settings.
   void beginTransaction(SPISettings settings)
   {
+    this->bitOrder = settings.bitOrder;
     #ifdef SPI_TRANSACTION_MISMATCH_LED
     if (inTransactionFlag) {
       pinMode(SPI_TRANSACTION_MISMATCH_LED, OUTPUT);
@@ -94,7 +98,7 @@ class SPIClass: public ObservableDataStream {
   uint16_t transfer16(uint16_t data) {
     union { uint16_t val; struct { uint8_t lsb; uint8_t msb; }; } in, out;
     in.val = data;
-    if (!(SPCR & (1 << DORD))) {
+    if (bitOrder == MSBFIRST) {
       out.msb = transfer(in.msb);
       out.lsb =  transfer(in.lsb);
     } else {
@@ -143,6 +147,7 @@ class SPIClass: public ObservableDataStream {
   #endif
 
   bool isStarted = false;
+  uint8_t bitOrder;
   String* dataIn;
   String* dataOut;
 };
diff --git a/cpp/arduino/avr/io.h b/cpp/arduino/avr/io.h
index f07699a0..41c9811b 100644
--- a/cpp/arduino/avr/io.h
+++ b/cpp/arduino/avr/io.h
@@ -96,7 +96,15 @@
 #ifndef _AVR_IO_H_
 #define _AVR_IO_H_
 
-#define _SFR_IO8(io_addr) (io_addr) // this macro is all we need from the sfr file
+#include <stdint.h>
+
+// hardware mocks
+extern volatile uint8_t __ARDUINO_CI_SFR_MOCK[1024];
+#define _SFR_IO8(io_addr) (*(volatile uint8_t *)(__ARDUINO_CI_SFR_MOCK + io_addr)) // this macro is all we need from the sfr file
+#define _SFR_IO16(io_addr) (*(volatile uint16_t *)(__ARDUINO_CI_SFR_MOCK + io_addr)) // this macro is all we need from the sfr file
+#define _SFR_MEM8(io_addr) (*(volatile uint8_t *)(__ARDUINO_CI_SFR_MOCK + io_addr)) // this macro is all we need from the sfr file
+#define _SFR_MEM16(io_addr) (*(volatile uint16_t *)(__ARDUINO_CI_SFR_MOCK + io_addr)) // this macro is all we need from the sfr file
+#define _SFR_MEM32(io_addr) (*(volatile uint32_t *)(__ARDUINO_CI_SFR_MOCK + io_addr)) // this macro is all we need from the sfr file
 
 #if defined (__AVR_AT94K__)
 #  include "ioat94k.h"