Abstract: In a contention avoidance control device and a contention avoidance control method for PWM output and A/D conversion, the change timings of PWM outputs are detected, and output of a received A/D conversion trigger to an A/D conversion circuit is inhibited within a predetermined time measured based on the change timings.

Abstract: In a contention avoidance control device and a contention avoidance control method for PWM output and A/D conversion, the change timings of PWM outputs are detected, and output of a received A/D conversion trigger to an A/D conversion circuit is inhibited within a predetermined time measured based on the change timings.

Abstract: The potential of a smoothing capacitor for a speaker is smoothly changed by controlling the potential with use of a PWM signal and switching between outputting the PWM signal and an actual audio signal, thereby suppressing a pop sound. The scale of circuitry is reduced and cost is lowered by implementing a PWM circuit in a one-chip microcontroller. Noise is eliminated by outputting a pulse that has been divided in the PWM signal generation stage.

Abstract: In a tone output device 100, an oscillator 102 outputs a clock 141 that is emitted by a crystal resonator. A multiplication circuit 103 outputs a clock 142 that is generated by multiplying the clock 141. A timing control circuit 104 outputs a timing signal 150 generated based on the clock 142 for operations of a CPU 105. The CPU 105 operates in sync with the timing signal 150. The DA converter 115 operates in sync with a signal generated based on the clock 141. The timing adjustment circuit 114 detects deviation of the clock 142 from the clock 141 resulting from frequency jitter of the clock 142, and prevents occurrence of clock racing.

Abstract: The voltage on the most sensitive noise sensing line that is thin and long inside in terms of layout and is near the power supply line or the ground line is captured by use of the system clock. A layout fixing logic constituted by a flip-flop is provided, and only when the voltage on the noise sensing line is changed due to noise or the like, first sensing data is outputted at low level from the layout fixing logic. Noise immunity characteristics can be improved by changing the circuit operation of the memory by the first sensing data.

Abstract: The potential of a smoothing capacitor for a speaker is smoothly changed by controlling the potential with use of a PWM signal and switching between outputting the PWM signal and an actual audio signal, thereby suppressing a pop sound. The scale of circuitry is reduced and cost is lowered by implementing a PWM circuit in a one-chip microcontroller. Noise is eliminated by outputting a pulse that has been divided in the PWM signal generation stage.

Abstract: In a tone output device 100, an oscillator 102 outputs a clock 141 that is emitted by a crystal resonator. A multiplication circuit 103 outputs a clock 142 that is generated by multiplying the clock 141. A timing control circuit 104 outputs a timing signal 150 generated based on the clock 142 for operations of a CPU 105. The CPU 105 operates in sync with the timing signal 150. The DA converter 115 operates in sync with a signal generated based on the clock 141. The timing adjustment circuit 114 detects deviation of the clock 142 from the clock 141 resulting from frequency jitter of the clock 142, and prevents occurrence of clock racing.