User's Manual

Cinterion
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EHS8 Hardware Interface Overview Page 20 of 43
2.1 Application Interface
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EHS8_HIO_v02.770 2014-08-11
Confidential / Preliminary
impedance traces. The trace length of these signals should be balanced to minimize timing
skew and no longer as 100mm.
Four signal lines for Link Power Management (LPM). For further power reduction, the USB
HSIC interface supports LPM according to the USB 2.0 standard. The LPM defines power
management states and mechanisms to affect state changes that are used b y the
AP_WAKEUP and CP_WAKEUP signal lines to efficiently manage bus and system power.
To take advantage of the LPM feature, two further signals are needed to support power
management state transitions - the SUSPEND and HOST_ACTIVE signals.
2.1.10 PWM Interfaces
The GPIO6 and GPIO7 interface lines can be configured as Pulse Width Modulation interface
lines PWM1 and PWM2. The PWM interface lines can be used, for example, to connect
buzzers. The PWM1 line is shared with GPIO7 and the PWM2 line is shared with GPIO6 (for
GPIOs see
Section 2.1.6). GPIO and PWM functionality are mutually exclusive.
2.1.11 Pulse Counter
The GPIO8 line can be configured as pulse counter line COUNTER. The pulse counter interface
can be used, for example, as a clock (for GPIOs see
Section 2.1.6).
2.1.12 Status LED
The GPIO5 interface line can be configured to drive a status LED that indicates different
operating modes of the module (for GPIOs see
Section 2.1.6). GPIO and LED functionality
are mutually exclusive.
2.1.13 Fast Shutdown
The GPIO4 interface line can be configured as fast shutdown signal line FST_SHDN. The
configured FST_SHDN line is an active low control signal and must be applied for at least 10
milliseconds. If unused this line can be left open because of a configured internal pull-up resistor.