1 files changed, 80 insertions, 0 deletions
diff --git a/docs/references/spi.md b/docs/references/spi.md
new file mode 100644
index 0000000..f63d304
--- /dev/null
+++ b/docs/references/spi.md
@@ -0,0 +1,80 @@
+Serial peripheral interface
+===========================
+To use include: `spi.h`  
+This interface is link to MOSI and MISO pins. Also SS pin is used when slave mode
+initialized.
+
+Configuration
+-------------
+To use SPI you must enable `CONFIG_SPI` configuration symbol.
+
+References
+----------
+### Function spi\_init
+```C
+static inline void spi_init(enum spiMode mode)
+```
+Initializes SPI interface.  
+Parameters:  
+    mode - Specify mode of SPI interface  
+  
+NOTE: Global interrupts must be enabled for right function of SPI.
+
+### Function spi\_busy
+```C
+static inline int8_t spi_busy(void)
+```
+Returns NULL when device is not busy.  
+When device is busy return values in non-zero.
+
+### Function spi\_join    
+```C
+static inline void spi_join(void)
+```
+Blocks processor until device is not busy.
+
+### Function spi\_send
+```C
+static inline uint8_t spi_send(uint8_t data)
+```
+Swap bytes with slave over SPI.  
+This function blocks execution until device isn't busy (transfer completed).  
+WARNING: Invoke this only when interface is initialized in MASTER mode.
+
+### Function spi\_transfer
+```C
+static inline void spi_transfer(uint8_t data)
+```
+Transfer byte to slave over SPI.  
+This function isn't blocking execution until transfer is complete.  
+Always call spi\_join before this function when called outside of spi\_receive().  
+WARNING: Invoke this only when interface is initialized in MASTER mode.
+
+### Function spi\_expose
+```C
+static inline void spi_expose(uint8_t data)
+```
+Expose data for next master request.
+Please don't use this when device is busy.
+Best place to call this is spi\_receive().  
+WARNING: Invoke this only when interface is initialized in SLAVE mode.
+
+### Function pointer spi\_receive
+```C
+extern void (*spi_receive)(uint8_t data)
+```
+This function is called every time transfer is finished.
+And until return from this function interrupts are disabled.
+
+### Enum spiMode
+```C
+enum spiMode {
+    SPI_MODE_MASTER,
+    SPI_MODE_SLAVE
+};
+```
+This is used as parameter for spi\_init function.
+
+Relevant examples
+-----------------
+* spiblink