controlling program flow

Hello Philip J,

The SigmaStudio compiler determines the execution order first by the flow of blocks in your schematic (blocks whose outputs are needed by other blocks of course execute first). Where there's several independent flows, often the blocks placed in the schematic first, show up earlier in the program. This being said, you'll be pleased to know that in Sigma-land, you never need to trace frame execution by viewing extra logic outputs with an oscilloscope. SigmaStudio keeps track of the instructions used when it compiles your signal flow, and won't let an "overloaded" program run. Say goodbye to the "half-sample rate" nonsense that can happen in C or assembler programming -- I promise you won't miss it.

For how to check your instruction (frame time) usage, please see:

https://ez.analog.com/message/47016#47016

Best regards.

Bob

Hello Philip,

It's possible to do what you asked for, but it takes a few tricks. At top left in this schematic is an inverter with feedback to itself, making it chase its tail to produce a fs/2 = 24 KHz clock. It feeds a string of MIPS-hungry functions which then "connects" (with a gain of zero) to a second fs/2 clock. Connecting them to opposite ends of the main signal chain this way forces them to be at opposite ends of the DSP code. Each clock feeds its own GPIO, so we can see the timing difference with a dual-trace scope.

The result below, shows the time difference between the two clocks:

It's 15 uS out of the total MIPS time of 1/fs = 20.8 us, or 738 instructions worth. The total instruction count of this project is 749.

Bob

Wow Bob, that's very clever.

Cheers

Miguel