Jack, thank you for your answer. I started from simple task however no luck yet. I added I2C to wishbone 9 and attached signals to pins Arduino_7 and Arduino_6 like in provided example. For sketch I used next modified code (originally provided for Wire arduino library): #include <i2c.h> #define DAC_ADDR 0x60 int lookup = 0; // index int mysin[512] = { 2048, 2073, 2098, 2123, 2148, 2174, 2199, 2224, … 1847, 1872, 1897, 1922, 1948, 1973, 1998, 2023 }; void setup() { I2C.begin(100000); I2C.enable(); } void loop() { I2C.start(DAC_ADDR,0); I2C.tx(64); I2C.tx(mysin[lookup] >> 4); I2C.tx((mysin[lookup] & 15) << 4); I2C.stop(); lookup = (lookup + 1) & 511; } Unfortunately I don’t see any activity at Pins 6 an 7. I would like to ask some questions which could help me moving forward: How need I declare in sketch that I attach I2C to wishbone 9 at ZPUino soft processor? What is second argument in function I2C.start? Thank you rmb