diff --git a/configs/stm3210e-eval/include/board.h b/configs/stm3210e-eval/include/board.h
index 30ad0ae985..9968957c21 100755
--- a/configs/stm3210e-eval/include/board.h
+++ b/configs/stm3210e-eval/include/board.h
@@ -85,7 +85,7 @@
 #define STM32_RCC_CFGR_PPRE1   RCC_CFGR_PPRE1_HCLKd2
 #define STM32_PCLK1_FREQUENCY  (STM32_HCLK_FREQUENCY/2)
 
-/* USB divider */
+/* USB divider -- Divide PLL clock by 1.5 */
 
 #define STM32_CFGR_USBPRE      0