diff --git a/ssd1306.c b/ssd1306.c
--- a/ssd1306.c
+++ b/ssd1306.c
@@ -83,7 +83,8 @@ void SSD1303_Init(void)
 {
   /* Generate a reset */
   SSD_Reset_Low();
-  for(u32 i=5000;--i;);//ÑÓʱ5uSÒÔÉÏ
+  uint32_t i ;
+  for(i=5000;--i;);
   SSD_Reset_High();
   
   /*************************************************
@@ -223,7 +224,8 @@ unsigned long SSD1303_OFF(void)
 {
   if(iS_SSD_On){
 #ifdef  DEBUG_UI
-    for(u32 i=0;i<SSD1303_COLUMN_NUMBER*SSD1303_PAGE_NUMBER;i++){
+    uint32_t i = 0;
+    for(i=0;i<SSD1303_COLUMN_NUMBER*SSD1303_PAGE_NUMBER;i++){
       SSD1303_Buffer[i] = 0;
     }
 #else
@@ -299,18 +301,18 @@ void  OnPageTransferDone(void)
     WriteCommand(0x10);
   }
   SSD_A0_High();
-  DMA1_Channel5->CCR &= ((u32)0xFFFFFFFE);
+  DMA1_Channel5->CCR &= ((uint32_t)0xFFFFFFFE);
   DMA1_Channel5->CNDTR = SSD1303_COLUMN_NUMBER+SSD1303_COLUMN_MARGIN_START + SSD1303_COLUMN_MARGIN_END;
-  DMA1_Channel5->CMAR = (u32)(SSD1303_Buffer+SSD1303_COLUMN_NUMBER*pageIndex - SSD1303_COLUMN_MARGIN_START);
-  DMA_SSD_1303->CCR |= ((u32)0x00000001);
+  DMA1_Channel5->CMAR = (uint32_t)(SSD1303_Buffer+SSD1303_COLUMN_NUMBER*pageIndex - SSD1303_COLUMN_MARGIN_START);
+  DMA_SSD_1303->CCR |= ((uint32_t)0x00000001);
   pageIndex++;
 #else
   SSD_A0_High();
-  DMA_SSD_1303->CCR &= ((u32)0xFFFFFFFE);
+  DMA_SSD_1303->CCR &= ((uint32_t)0xFFFFFFFE);
   DMA_SSD_1303->CNDTR = SSD1303_COLUMN_NUMBER*SSD1303_PAGE_NUMBER;//+SSD1303_COLUMN_MARGIN_START + SSD1303_COLUMN_MARGIN_END;
-  DMA_SSD_1303->CMAR = (u32)(SSD1303_Buffer);//+SSD1303_COLUMN_NUMBER*pageIndex);
+  DMA_SSD_1303->CMAR = (uint32_t)(SSD1303_Buffer);//+SSD1303_COLUMN_NUMBER*pageIndex);
   //DMA_Cmd(DMA_SSD_1303, ENABLE);
-  DMA_SSD_1303->CCR |= ((u32)0x00000001);
+  DMA_SSD_1303->CCR |= ((uint32_t)0x00000001);
 //  pageIndex++;
   pageIndex = SSD1303_PAGE_NUMBER;
 #endif
@@ -389,7 +391,9 @@ unsigned long SSD1303_DrawBlock(
     unsigned char mask1 = (1<<offset1)-1;
     unsigned char mask2 = ~((1<<offset2)-1);
     cy = (cy+offset1)/8;
-    for(Pos_t i=0;i<cx;i++){
+   
+    Pos_t i = 0;
+    for(i=0;i<cx;i++){
       Pos_t j = 0;
       unsigned short tmp = *pStart & mask1;
       for(;j<cy;j++){
@@ -409,7 +413,9 @@ unsigned long SSD1303_DrawBlock(
     unsigned char mask1 = ~((1<<offset1)-1);
     unsigned char mask2 = ((1<<offset2)-1);
     cy = (cy+offset1)/8;
-    for(Pos_t i=0;i<cx;i++){
+
+    Pos_t i = 0;
+    for(i=0;i<cx;i++){
       Pos_t j = 1;
       *pStart ^= mask1;
       for(;j<cy;j++){
@@ -512,7 +518,8 @@ unsigned long SSD1303_ReadPoint(
 void  SSD1303_FillScreen(Color_t color)
 {
   unsigned char mask = color ? 0xFF : 0;
-  for(unsigned long i=0;i<SSD1303_COLUMN_NUMBER*SSD1303_PAGE_NUMBER;i++){
+  unsigned long i = 0;
+  for(i=0;i<SSD1303_COLUMN_NUMBER*SSD1303_PAGE_NUMBER;i++){
     SSD1303_Buffer[i] = mask;
   }
 }