Gpio Interface; Using The Gpio10 Pin As Pulse Counter - Siemens AC75 Hardware Interface Description

AC75 Hardware Interface Description
Strictly confidential / Preliminary
3.16

GPIO Interface

The AC75 has 10 GPIOs for external hardware devices. Each GPIO can be configured for
use as input or output. All settings are AT command controlled.
The GIPO related AT commands are the following: AT^SPIO, AT^SCPIN, AT^SCPOL,
AT^SCPORT, AT^SDPORT, AT^SGIO, AT^SSIO. A detailed description can be found in [1].
3.16.1

Using the GPIO10 Pin as Pulse Counter

The GPIO10 pin can be assigned two different functions selectable by AT command:
•
The AT^SCPIN command configures the pin for use as GPIO.
•
With AT^SCCNT and AT^SSCNT the pin can be configured and operated as pulse
counter.
Both functions exclude each other. The pulse counter disables the GPIO functionality, and
vice versa, the GPIO functionality disables the pulse counter. Detailed AT command
descriptions can be found in [1].
The pulse counter is designed to measure signals from 0 to 1000 pulses per second. It can
be operated either in Limit counter mode or Start-Stop mode. Depending on the selected
mode the counted value is either the number of pulses or the time (in milliseconds) taken to
generate a number of pulses specified with AT^SCCNT.
In Limit counter mode, the displayed measurement result (URC "^SSCNT: <count>") implies
an inaccuracy <5ms. In Start-Stop mode, you can achieve 100% accuracy if you take care
that no pulses are transmitted before starting the pulse counter (AT^SSCNT=0 or 1) and
after closing the pulse counter (AT^SSCNT=3).
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27.04.2006