Table of Contents
24/7 Data Acquisition Wildcard Users Guide
The following section describes the high-level software routines that initialize, calibrate, configure, and command the 24/7 Data Acquisition Wildcard. Once the 24/7 Data Acquisition Wildcard is commanded to start converting, it continually samples and converts at a fixed rate. You can read the output once or store each sequential conversion to a memory buffer. Only one channel is sampled at a time; selecting a new channel requires restarting a conversion.
The software routines use global variables to store the current module and channel information. Thus all of the 24/7 Data Acquisition Wildcard software routines are non-re-entrant and only a single task in a multitasking application can use a 24/7 Data Acquisition Wildcard.
Please take time to read through the example programs. The examples illustrate how to effectively use the pre-coded software drivers. Many subtleties involved with using the 24/7 Data Acquisition Wildcard are highlighted in the example code.
The following steps and corresponding routines are required to obtain a sample from the 24/7 Data Acquisition Wildcard:
Each step is described in detail in the next four sections.
To initialize the 24/7 Data Acquisition Wildcard, call Init_AD24. This configures the module for communication via the Mosaic controllerís Serial Peripheral Interface (SPI), starts the controllerís Timeslicer, and performs a reset (Reset_AD24) that disconnects all of the analog inputs from the AD7714 and resets its digital filter, analog modulator, and registers.
Once the module is initialized, you must choose what type of reference voltage to use. To use the on-board 2.5 V reference voltage, simply call Use_Onboard_Ref and make sure the jumper shunt on J1 is not installed. If an external reference voltage is required, connect the reference voltage to FDREF+ (pin 9 on H2) and FDREF- (pin 11 on H2) and call Use_External_Ref. These two routines connect the specified reference voltage to the reference input on the analog to digital converter. Be sure to only use 1.0 to 2.5 volts as an external reference voltage and be sure that FDREF+ is more positive with respect to FDREF-.
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