-#define AO_SPI_SPEED_8MHz STM_SPI_CR1_BR_PCLK_2
-#define AO_SPI_SPEED_4MHz STM_SPI_CR1_BR_PCLK_4
-#define AO_SPI_SPEED_2MHz STM_SPI_CR1_BR_PCLK_8
-#define AO_SPI_SPEED_1MHz STM_SPI_CR1_BR_PCLK_16
-#define AO_SPI_SPEED_500kHz STM_SPI_CR1_BR_PCLK_32
-#define AO_SPI_SPEED_250kHz STM_SPI_CR1_BR_PCLK_64
-#define AO_SPI_SPEED_125kHz STM_SPI_CR1_BR_PCLK_128
-#define AO_SPI_SPEED_62500Hz STM_SPI_CR1_BR_PCLK_256
+//#define AO_SPI_SPEED_8MHz STM_SPI_CR1_BR_PCLK_2 /* too fast to use safely */
+#define _AO_SPI_SPEED_4MHz STM_SPI_CR1_BR_PCLK_4
+#define _AO_SPI_SPEED_2MHz STM_SPI_CR1_BR_PCLK_8
+#define _AO_SPI_SPEED_1MHz STM_SPI_CR1_BR_PCLK_16
+#define _AO_SPI_SPEED_500kHz STM_SPI_CR1_BR_PCLK_32
+#define _AO_SPI_SPEED_250kHz STM_SPI_CR1_BR_PCLK_64
+#define _AO_SPI_SPEED_125kHz STM_SPI_CR1_BR_PCLK_128
+#define _AO_SPI_SPEED_62500Hz STM_SPI_CR1_BR_PCLK_256