Somewhat confusingly, the pin is configured as “analog in”. The name is a bit misleading because the DAC module drives the pin when configured. However, this configuration does perform the important function of disconnecting any digital input buffer Once a DAC is initialized, data may be written using the following commands (defined in stm32f10x_dac.[ch] where align is one of DAC_Align_12b_R, DAC_Align_12b_L, DAC_Align_8b_R.