diff --git a/libraries/AP_HAL_AVR/SPIDevice_SPI0.cpp b/libraries/AP_HAL_AVR/SPIDevice_SPI0.cpp
index b5b4baa01e..7b155d1d3a 100644
--- a/libraries/AP_HAL_AVR/SPIDevice_SPI0.cpp
+++ b/libraries/AP_HAL_AVR/SPIDevice_SPI0.cpp
@@ -36,7 +36,7 @@ AP_HAL::Semaphore* AVRSPI0DeviceDriver::get_semaphore() {
     return &_semaphore;
 }
 
-void AVRSPI0DeviceDriver::cs_assert() {
+inline void AVRSPI0DeviceDriver::_cs_assert() {
     const uint8_t valid_spcr_mask = 
         (_BV(CPOL) | _BV(CPHA) | _BV(SPR1) | _BV(SPR0));
     uint8_t new_spcr = SPCR | (_spcr & valid_spcr_mask);
@@ -49,11 +49,11 @@ void AVRSPI0DeviceDriver::cs_assert() {
     _cs_pin->write(0);
 }
 
-void AVRSPI0DeviceDriver::cs_release() {
+inline void AVRSPI0DeviceDriver::_cs_release() {
     _cs_pin->write(1);
 }
 
-uint8_t AVRSPI0DeviceDriver::transfer(uint8_t data) {
+inline uint8_t AVRSPI0DeviceDriver::_transfer(uint8_t data) {
     if (spi0_transferflag) {
         hal.scheduler->panic(PSTR("PANIC: SPI0 transfer collision"));
     }
@@ -69,4 +69,25 @@ uint8_t AVRSPI0DeviceDriver::transfer(uint8_t data) {
     return read_spdr;
 }
 
+void AVRSPI0DeviceDriver::transaction(const uint8_t *tx, uint8_t *rx,
+        uint16_t len) {
+    _cs_assert();
+    for (uint16_t i = 0; i < len; i++) {
+        rx[i] = _transfer(tx[i]);
+    }
+    _cs_release();
+}
+
+void AVRSPI0DeviceDriver::cs_assert() {
+    _cs_assert();
+}
+
+void AVRSPI0DeviceDriver::cs_release() {
+    _cs_release();
+}
+
+uint8_t AVRSPI0DeviceDriver::transfer(uint8_t data) {
+    return _transfer(data);
+}
+
 #endif
diff --git a/libraries/AP_HAL_AVR/SPIDevice_SPI2.cpp b/libraries/AP_HAL_AVR/SPIDevice_SPI2.cpp
index 8ee0d9887c..baca5ea246 100644
--- a/libraries/AP_HAL_AVR/SPIDevice_SPI2.cpp
+++ b/libraries/AP_HAL_AVR/SPIDevice_SPI2.cpp
@@ -38,7 +38,7 @@ AP_HAL::Semaphore* AVRSPI2DeviceDriver::get_semaphore() {
     return &_semaphore;
 }
 
-void AVRSPI2DeviceDriver::cs_assert() {
+inline void AVRSPI2DeviceDriver::_cs_assert() {
     /* set the device UCSRnC configuration bits.
      * only sets data order, clock phase, and clock polarity bits (lowest
      * three bits)  */
@@ -50,11 +50,11 @@ void AVRSPI2DeviceDriver::cs_assert() {
     _cs_pin->write(0);
 }
 
-void AVRSPI2DeviceDriver::cs_release() {
+inline void AVRSPI2DeviceDriver::_cs_release() {
     _cs_pin->write(1);
 }
 
-uint8_t AVRSPI2DeviceDriver::transfer(uint8_t data) {
+inline uint8_t AVRSPI2DeviceDriver::_transfer(uint8_t data) {
     /* Wait for empty transmit buffer */
     while ( !( UCSR2A & _BV(UDRE2)) ) ;
 
@@ -68,4 +68,25 @@ uint8_t AVRSPI2DeviceDriver::transfer(uint8_t data) {
     return UDR2;
 }
 
+void AVRSPI2DeviceDriver::transaction(const uint8_t *tx, uint8_t *rx,
+        uint16_t len) {
+    _cs_assert();
+    for (uint16_t i = 0; i < len; i++) {
+        rx[i] = _transfer(tx[i]);
+    }
+    _cs_release();
+}
+
+void AVRSPI2DeviceDriver::cs_assert() {
+    _cs_assert();
+}
+
+void AVRSPI2DeviceDriver::cs_release() {
+    _cs_release();
+}
+
+uint8_t AVRSPI2DeviceDriver::transfer(uint8_t data) {
+    return _transfer(data);
+}
+
 #endif
diff --git a/libraries/AP_HAL_AVR/SPIDevice_SPI3.cpp b/libraries/AP_HAL_AVR/SPIDevice_SPI3.cpp
index 126b90d53c..ee245cc42e 100644
--- a/libraries/AP_HAL_AVR/SPIDevice_SPI3.cpp
+++ b/libraries/AP_HAL_AVR/SPIDevice_SPI3.cpp
@@ -43,7 +43,7 @@ AP_HAL::Semaphore* AVRSPI3DeviceDriver::get_semaphore() {
     return &_semaphore;
 }
 
-void AVRSPI3DeviceDriver::cs_assert() {
+void AVRSPI3DeviceDriver::_cs_assert() {
     /* set the device UCSRnC configuration bits.
      * only sets data order, clock phase, and clock polarity bits (lowest
      * three bits)  */
@@ -55,11 +55,11 @@ void AVRSPI3DeviceDriver::cs_assert() {
     _cs_pin->write(0);
 }
 
-void AVRSPI3DeviceDriver::cs_release() {
+void AVRSPI3DeviceDriver::_cs_release() {
     _cs_pin->write(1);
 }
 
-uint8_t AVRSPI3DeviceDriver::transfer(uint8_t data) {
+uint8_t AVRSPI3DeviceDriver::_transfer(uint8_t data) {
     /* Wait for empty transmit buffer */
     while ( !( UCSR3A & _BV(UDRE3)) ) ;
 
@@ -73,4 +73,25 @@ uint8_t AVRSPI3DeviceDriver::transfer(uint8_t data) {
     return UDR3;
 }
 
+void AVRSPI3DeviceDriver::transaction(const uint8_t *tx, uint8_t *rx,
+        uint16_t len) {
+    _cs_assert();
+    for (uint16_t i = 0; i < len; i++) {
+        rx[i] = _transfer(tx[i]);
+    }
+    _cs_release();
+}
+
+void AVRSPI3DeviceDriver::cs_assert() {
+    _cs_assert();
+}
+
+void AVRSPI3DeviceDriver::cs_release() {
+    _cs_release();
+}
+
+uint8_t AVRSPI3DeviceDriver::transfer(uint8_t data) {
+    return _transfer(data);
+}
+
 #endif
diff --git a/libraries/AP_HAL_AVR/SPIDevices.h b/libraries/AP_HAL_AVR/SPIDevices.h
index a494e8be31..43ff1f6c02 100644
--- a/libraries/AP_HAL_AVR/SPIDevices.h
+++ b/libraries/AP_HAL_AVR/SPIDevices.h
@@ -19,11 +19,18 @@ public:
 
     void init();
     AP_HAL::Semaphore* get_semaphore();
+
+    void transaction(const uint8_t *tx, uint8_t *rx, uint16_t len);
+
     void cs_assert();
     void cs_release();
     uint8_t transfer(uint8_t data);
 
 private:
+    void _cs_assert();
+    void _cs_release();
+    uint8_t _transfer(uint8_t data);
+
     static AP_HAL_AVR::AVRSemaphore _semaphore;
 
     AP_HAL_AVR::AVRDigitalSource *_cs_pin;
@@ -46,11 +53,18 @@ public:
 
     void init();
     AP_HAL::Semaphore* get_semaphore();
+
+    void transaction(const uint8_t *tx, uint8_t *rx, uint16_t len);
+
     void cs_assert();
     void cs_release();
     uint8_t transfer(uint8_t data);
 
 private:
+    void _cs_assert();
+    void _cs_release();
+    uint8_t _transfer(uint8_t data);
+
     static AP_HAL_AVR::AVRSemaphore _semaphore;
 
     AP_HAL_AVR::AVRDigitalSource *_cs_pin;
@@ -72,11 +86,17 @@ public:
 
     void init();
     AP_HAL::Semaphore* get_semaphore();
+
+    void transaction(const uint8_t *tx, uint8_t *rx, uint16_t len);
+
     void cs_assert();
     void cs_release();
     uint8_t transfer(uint8_t data);
 
 private:
+    void _cs_assert();
+    void _cs_release();
+    uint8_t _transfer(uint8_t data);
     static AP_HAL_AVR::AVRSemaphore _semaphore;
 
     AP_HAL_AVR::AVRDigitalSource *_cs_pin;