Some kind of function generator and it needs sine, square, sawtooth and traingle. the " sine, square, sawtooth" are done by a DDS and now I need the sawtooth.
Indeed I also thought that, generate it from a SPI DAC, but lets take a look.
fosc µC = 40MHz, spi clk = fosc/4 = 10 MHz ( SPI DAC = 20 MHz), 2 bytes need to be sent to set the output voltage => update at = 10MHz/16 =625 kHz. Lets say a sawtooth 0 to 5V, Deltva V? 100 steps? f sawtooth = 6,25kHz . I can use some kind of recovery filter but the cut off frequency has to be variable...