| 摘要 |
<p>A system for synchronising the operation of a measurement instrument having a microcontroller, a local oscillator and function circuitry to an external timebase. The system comprises a USB Host Controller; an interrupt generator adapted to respond to ITPs by generating respective interrupts and passing the interrupts to the microcontroller; and a timer for measuring an interval between receptions of the ITPs in a time domain of the local oscillator. The system is adapted to control the instrument to open one or more Isochronous communication pipes or endpoints to the USB Host Controller, to ensure that the instrument is in link state U0 in preparation for receiving a plurality of ITPs and to control the USB Host Controller to send a plurality of the ITPs to the Isochronous communication pipes or endpoints, the microcontroller is configured to respond to each of the plurality of interrupts by generating an output signal adapted to be used as a synchronization reference signal, and the instrument is configured to create a mapping between respective local times of a plurality of operations or events of the function circuitry of the instrument and a time domain of the USB Host Controller. The system may comprise the instrument. The instrument may be a Super Speed USB device.</p> |
