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ADVANCED COMMUNICATIONS & SENSING
USER GUIDE
SX8724SEVK
Evaluation Kit for SX8724S Data Acquisition System
ACS - Revision 1.0 May 2011
© Semtech Corp.
13.4.4 ADC controls
The group of controls named “ADC” lets the user control the ADC parameters. Parameters like number of
elementary conversions, the over-sampling rate, the sampling frequency at the input and the ADC biasing
current ratio can be tuned.
Select the correct input sampling frequency depending on the required input impedance and conversion
time. If necessary and/or possible, the power consumption can be reduced using the biasing parameters.
However, if the biasing current is too low, the performance of the ZoomingADC will be adversely affected.
Select the ADC parameters for the required resolution using over-sampling rate (OSR) and number of
elementary conversions (N
ELCONV
). Prefer over-sampling rate since it increases much faster the resolution
then N
ELCONV
. If the offset is important, select a number of elementary conversions > 1.
The user has also the possibility to decide if the ADC will work in single shot or in continuous mode of
samples acquisition.
13.4.5 General Controls
The general control provides an indication of the status of the GPIO and settings.
Please refer to the SX8724S datasheet for a detailed description.
13.4.6 RC Oscillator
The
RC oscillator
provides the master clock reference for the chip. It produces a clock at 4 MHz which is
divided internally in order to generate the clock sources needed by the other blocks.
It can be disabled to set de device in a low power mode. Any SPI command will wake up the RC oscillator
automatically.
13.4.7 GPIO
The direction of each bit within the GPIO block (input only or input/output) can be individually set using the
GPIO controls. If direction is set as “OUT”, the corresponding pin can be set as output high or low. The digital
pins are able to deliver a driving current up to 8 mA.
D0 and D1 are multi-functional pins, see
. for GPIO with V
REF
functionality.
Figure 21. General Control
