Datasheet

Internal Indexer Mode

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On the CPG006 board, the algorithm to compute acceleration, steady state, and deceleration is an hybrid

of two functions: How fast we are modifying the stepping rate so that a desired speed is reached and how

many steps we have allocated to modify said rate. This translates to two mechanisms on terminating the

acceleration profile. Either acceleration/deceleration culminates as we reach the desired/start speed, or as

the allocated number of steps elapses.

It is important to understand these two clauses are mutually exclusive; depending on which one is reached

first, the other one will be affected.

For example, if the acceleration percentage is too small, the acceleration profile will be capped by the

available number of steps, in which case the desired speed will most likely not be reached.

If the acceleration percentage is too high, then the desired speed will finish the acceleration profile and

whatever steps are left on the acceleration profile will be assigned to the steady state portion.

The user will find many different behaviors that are too numerous to mention and beyond the scope of this

guide. Experimentation will show all the possibilities present within this acceleration algorithm.

5 Internal Indexer Mode

When the SER_MODE (S1:8) signal is made HI, the microcontroller is configured to operate as an internal

indexer. In this mode, the serial communications channel is disabled and connection from a PC is not

necessary. User will operate the stepper driver by issuing their own signals through connectors J10 and

J11 as described in section 2.5 of this guide.

6 Schematics

A complete schematic for the DRV882xEVM is appended to this user's guide. It is also available in the

form of a PDF file (CPG006_Schematic.pdf) in the EVM Related folder in the product folder for the

downloadable EVM software package.

DRV882x Evaluation Modules SLMU002– June 2011

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