The Logic System

Each of the DSP configurable Soundweb London devices also contains a configurable logic system. You can toggle between the audio configuration and logic configuration using the audio and logic buttons in the Configuration Window.

The Soundweb London processor contains several processing chips including a CPU (Central Processing Unit) and 2 or more DSPs (Digital Signal Processors). The CPU handles all communication (Ethernet, serial etc.), parameter linking, display, led's etc. The DSPs are for audio signal processing. The logic runs on the Soundweb London CPU, not the DSP. This means it will not use any DSP resources. However, it will use CPU resources which will be explained in more detail below.

Logic Objects are placed and wired up in the same way as in the audio configuration. Many of the logic objects have properties which allow you to add and/or remove input or output ports. Each logic object is quite basic, but when added together they can perform very complex operations, e.g. a priority paging system. Each logic object has a run order which can be displayed by enabling the option in the Logic Menu. The run order is the order in which the logic object will be processed. Attention must be paid to the run order if logic signals are looped back to previous logic objects (like a feedback loop) since the objects may then have a different run order to what you might expect.

Many logic objects have default control panels and parameters which can be controlled. These parameters allow you to interact with the logic system and also facilitate the logic system to interact with the audio system. You can for example link a logic end to a mute. The logic allows a quick method of creating these links. For example, you can drag and drop the mute control from a panel directly on to the logic end object in the logic configuration window. This will automatically create an exact link between the mute parameter and the logic end parameter. The link will appear in the Design Tree under 'Logic Links'.

Resource Meter

At the top of the logic configuration window is a logic resource meter which gives an indication of resource usage. Each logic object has an approximate host processor usage. It is approximate because it is impossible to calculate an exact figure. The resource meter is the total of these approximate values. 100% logic resource usage equates to approximately 50% host CPU usage. However, it is unlikely that you will see this amount of CPU usage being used. This is because there are optimisations in the logic which means that most logic objects will not be processed if no change is made to the inputs, in which case the logic object will not consume any host CPU usage. Other logic objects such as the Calendar object are processed every logic tick (100ms) and so can consume lots of host CPU usage. The logic resource meter therefore gives a worst case figure, based on every logic object being processed every tick. However, you should still not rely on this figure when determining if the logic will run successfully in the device. This is because the host processor which runs the logic also performs many other tasks which cannot be estimated by London Architect. Examples of items which affect host CPU usage are:- number of devices on the network, number of open control panels in London Architect, and cross-device linking.

The only way to determine if the device will successfully run the logic system is to go online with your design file and observe the CPU meter in the device default control panel. This will be required for every device running logic. If the figure is above 90% then there may be occasions where the logic will run slower than every 100ms, and meters will appear to slow down. In extreme cases, controls will grey out on control panels.