The Stage, Booster Stage, and Hostage modules can be chained together to create multi-stage envelopes.

For a chain of individual modules to generate a sequence of stages, they must coordinate with each other in two ways: Precedence and Sequence.

1. Precedence: Whenever an module is generating a stage, all successor modules must forward that signal all the way through the chain to the final OUT output.

   That is, each module has precedence over all successor modules. When a module wants control, each successor module must defer to it.

2. Sequence: As each module completes its stage, it must hand off control to its successor to start the next stage.

Coordinating Precedence

Modules coordinate precedence through their DEFER and ACTIVE ports.

In a typical configuration, each module’s ACTIVE output is connected to its successor’s DEFER input. And each module’s OUT output is connected to its successor’s IN input.

When a module is generating a stage, it holds its ACTIVE gate high and sends the generated stage to its OUT output.

When the next module receives this high gate signal at its DEFER input, it defers to its predecessor. It forwards its IN signal (the output from the predecessor) to its own OUT port.

In this way, the first module’s OUT signal makes its way to the second module’s OUT output.

In addition, while the second module is deferring, it holds its own ACTIVE gate high. This causes the next module to defer, and the next, and the next, all the way to the end of the chain.

Through this chain of ACTIVE/DEFER signals, the highest precedence module assumes control of the entire chain’s output.

Coordinating Sequence

Modules coordinate sequence through their TRIG and EOC ports.

In a typical configuration, each module’s EOC output is connected to its successor’s TRIG input.

As each module completes its stage, it sends two important coordination signals:

• It lowers its ACTIVE gate which relinquishes its control over the successor modules.
• It sends a short pulse on its EOC output, which hands off control to its successor.

And the next module reacts:

• Because its DEFER input is now low, it stops deferring.
• Because its TRIG input rose (because of the EOC pulse), it begins generating its own stage.
• Because it is actively generating a stage, it raises its own ACTIVE gate, giving it the highest precedence in the chain. And so all of the successor modules now defer to it.

In this way, the chain of modules creates a sequence of stages and sends each stage through the final OUT output of the chain.