1.) Tuner and demodulator are connected directly to the I2C bus. Direct access to the tuner. * tuner can be silicon tuner or simple PLL * uncommon coupling ____________ ____________ ____________ | uC | | demod | | tuner | |------------| |------------| |------------| | | | | | | | |--------I2C-+------| | +-I2C--------| | | | | | | | | | | | | | | | | | |____________| | |____________| | |____________| +--------------------------+ 2.) Tuner is connected via demodulator to the I2C bus. There is I2C-gate in the demodulator. * tuner can be silicon tuner or simple PLL * common coupling, probably most used nowadays * access to tuner is behind I2C-gate ____________ ____________ ____________ | uC | | demod | | tuner | |------------| |------------| |------------| | | | | | | | |--------I2C--------|-----/ -----|--------I2C--------| | | | | | | | | | | | | | |____________| |____________| |____________| 3.) Tuner is connected to the demodulator and driven by demodulator. There is no direct access to tuner in any case. * tuner can be only simple PLL * tuner is programmed by following steps: - write tuner I2C address to the demodulator (TUN_ADDR) - write tuner frequency to the demodulator (CHAN_START) - write tuner control word (charge pump & bw) to the demodulator (CONT) - write request program tuner to the demodulator (TUNER_GO) * after TUNER_GO demodulator writes all those values to the tuner ____________ ____________ ____________ | uC | | demod | | tuner | |------------| |------------| |------------| | | | | | | | |--------I2C--------|--o ~ o--|--------I2C--------| | | | | | | | | | | | | | |____________| |____________| |____________|