Bi-level Discrete Monitor (BDM) interface

The bi-level discrete monitor (BDM) interfaces are used for reasonably static, discrete status and telemetry monitoring by the core element. The monitored signal is bi-level discrete in that it can take only two values, high or low, indicated by the signal voltage. The bi-level discrete interface consists of a signal, BL_DATA_IN, which is generated by the peripheral element. This signal is sampled periodically by the core element.

In a practical implementation, a number of bi-level discrete interfaces can be aggregated to form a multiple bit data word in the core element. The bi-level discrete input interface consists of a signal, BL_DATA_IN, which can assume two values, high or low, with respect to the signal reference. This signal is maintained continuously by the peripheral element and can be sampled at any time by the core element. On sampling, the core element encodes the BL_DATA_IN value into a single binary bit of data which can be embedded in a larger data word. There are no timing parameters associated with this interface. The BL_DATA_IN signal is maintained continuously by the peripheral element and can generally be regarded as static. However, if the BL_DATA_IN signal is sampled during a transition from one level to the other, the result determined by the core element can be invalid.