Dimming circuit and lighting device

A dimming circuit, comprising:

• a plurality of a least two switching circuits, the plurality of at least two switching circuits configured to provide a to-be-processed dimming signal, wherein a switching circuit of the plurality of at least two switching circuits comprises a switch and a controllable switch, the switch being connected between a power source and a terminal of the controllable switch, the controllable switch configured to provide the to-be-processed dimming signal based on a state of the switch;
• a signal processing unit corresponding to each of the plurality of at least two switching circuits, the signal processing unit having a first controllable switch;
• the first controllable switch having a first terminal configured to receive the to-be-processed dimming signal from a corresponding one of the plurality of at least two switching circuits, a second terminal connected to a first port of a controller, and a third terminal connected to a first voltage signal;
• the to-be-processed dimming signal and the first voltage signal controlling turning-on and turning-off of the first controllable switch,
• the to-be-processed dimming signal being converted into a second voltage signal, and outputted from the second terminal to the first port of the controller;
• and
• the controller, extracting a corresponding dimming control signal from a stored set of preset dimming signals based on a change of the second voltage signal, and outputting the extracted dimming control signal to a to-be-dimmed terminal, wherein each switch of the plurality of at least two switching circuits corresponds to a different preset dimming signals.