The sysclk-lwla driver still suffers from occasional device hiccups on first use. The problem manifests itself by invalid USB reply lengths in response to the first commands sent to the device after firmware download.

Experimentation suggests that the problem occurs mostly when external voltages are applied to the input pins before or during initialization. However, sometimes the device also hiccups if connected hardware is switched on after initialization of the logic analyzer. In all cases, a physical USB disconnect and reconnect sequence is required to get the device to work again. Sometimes it is even necessary to repeat this step more than once.

In all cases, there seem to be no further problems once the device has been used successfully at least once.

My suspicion is that the problem is due to a missing device reset during driver initialization. If I understand the USB spec correctly, selecting the same USB device configuration as already configured is supposed to soft-reset the device. However, when I had this in the driver, the device *never* initialized correctly.

The original vendor software appears to reset both the interface and the configuration twice during application start-up. However, there seems to be something special still missing, because I could never get that initialization sequence to work.