+
+ /** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 1. */
+ #define TWI_BIT_PRESCALE_1 ((0 << TWPS1) | (0 << TWPS0))
+
+ /** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 4. */
+ #define TWI_BIT_PRESCALE_4 ((0 << TWPS1) | (1 << TWPS0))
+
+ /** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 16. */
+ #define TWI_BIT_PRESCALE_16 ((1 << TWPS1) | (0 << TWPS0))
+
+ /** Bit length prescaler for \ref TWI_Init(). This mask multiplies the TWI bit length prescaler by 64. */
+ #define TWI_BIT_PRESCALE_64 ((1 << TWPS1) | (1 << TWPS0))
+
+ /** Calculates the length of each bit on the TWI bus for a given target frequency. This may be used with
+ * the \ref TWI_Init() function to convert a bus frequency to a number of clocks for the \c BitLength
+ * parameter.
+ *
+ * \param[in] Prescale Prescaler set on the TWI bus.
+ * \param[in] Frequency Desired TWI bus frequency in Hz.
+ *
+ * \return Bit length in clocks for the given TWI bus frequency at the given prescaler value.
+ */
+ #define TWI_BITLENGTH_FROM_FREQ(Prescale, Frequency) ((((F_CPU / (Prescale)) / (Frequency)) - 16) / 2)
+