A method performed by a quality assurance integrated circuit for a print controller, the quality assurance integrated circuit comprising a memory; a system clock for generating a clock signal; clock trim circuitry for trimming the frequency of the clock signal; and a processor. the method includes, in the processor, in response to receiving an external signal, determining the number of cycles of the clock signal during a predetermined number of cycles of the external signal or the number of cycles of the external signal during a predetermined number of cycles of the clock signal and to output the determined number of cycles to an external circuit; and in response to receiving a trim value based on the determined number of cycles from the external circuit, storing the trim value in the memory and controlling the clock trim circuitry to trim the frequency of the clock signal using the trim value.