diff --git a/lib/ssd1306/ssd1306.c b/lib/ssd1306/ssd1306.c
--- a/lib/ssd1306/ssd1306.c
+++ b/lib/ssd1306/ssd1306.c
@@ -1,34 +1,21 @@
+//
+// ssd1306: OLED display driver
+//
+
 #include "stm32f3xx_hal.h"
 #include "ssd1306.h"
 
 
-SPI_HandleTypeDef hspi1;
-
-
-// SPI handle accessor
-SPI_HandleTypeDef* spi_get()
-{
-    return &hspi1;
-}
+// Private variables
+static SPI_HandleTypeDef hspi1;
 
 
-// Write command to OLED
-static void WriteCommand(unsigned char command)
-{
-  SSD_CS_Low();
-  SSD_A0_Low();
-  SPI_SendByte(command);
-  SSD_CS_High();
-}
+// Private method prototypes
+static void WriteCommand(unsigned char command);
+static void WriteData(unsigned char data);
+static void setStartPage(unsigned char d);
+static void setStartColumn(unsigned char d);
 
-// Write data to OLED
-static void WriteData(unsigned char data)
-{
-  SSD_CS_Low();
-  SSD_A0_High();
-  SPI_SendByte(data);
-  SSD_CS_High();
-}
 
 // Initialize OLED
 void ssd1306_init(void)
@@ -38,7 +25,7 @@ void ssd1306_init(void)
 	__GPIOB_CLK_ENABLE();
 	GPIO_InitTypeDef GPIO_InitStruct;
 
-	/*Configure GPIO pins : OLED_CS_Pin OLED_RESET_Pin OLED_DC_Pin */
+	// GPIO
 	GPIO_InitStruct.Pin = OLED_CS_Pin|OLED_RESET_Pin|OLED_DC_Pin;
 	GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 	GPIO_InitStruct.Pull = GPIO_NOPULL;
@@ -227,10 +214,27 @@ static const char fontData[][5] =
 	{0x22,0x5d,0x22,0x00,0x00},			//   (111) ez updown
 	{0x14,0x3e,0x14,0x00,0x00},         //   (112) ez updown short
 };
-/*
 
 
-*/
+// Write command to OLED
+static void WriteCommand(unsigned char command)
+{
+  SSD_CS_Low();
+  SSD_A0_Low();
+  SPI_SendByte(command);
+  SSD_CS_High();
+}
+
+
+// Write data to OLED
+static void WriteData(unsigned char data)
+{
+  SSD_CS_Low();
+  SSD_A0_High();
+  SPI_SendByte(data);
+  SSD_CS_High();
+}
+
 
 // Set start page
 static void setStartPage(unsigned char d)
@@ -248,7 +252,6 @@ static void setStartColumn(unsigned char
                                 // Default => 0x10
 }
 
-
 // Therm logo
 const uint8_t row[4][32] = {
 
@@ -439,4 +442,10 @@ void ssd1306_drawstringbig(const unsigne
 }
 
 
+// SPI handle accessor
+SPI_HandleTypeDef* spi_get()
+{
+    return &hspi1;
+}
+
 // vim:softtabstop=4 shiftwidth=4 expandtab