User's Manual

Table Of Contents

EHS5-E/EHS5-US Hardware Interface Overview

2.1 Application Interface

EHS5_HIO_v01.000 Page 15 of 35 2012-11-14

Confidential / Preliminary

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When the EHS5-E/EHS5-US starts up, all GPIO lines are set to high-impedance state after ini-

tializing. Therefore, it is recommended to connect external pull-up or pull-down resistors to all

GPIO lines you want to use as output. This is necessary to keep these lines from floating or

driving any external devices.

2.1.7 I

C Interface

C is a serial, 8-bit oriented data transfer bus for bit rates up to 400kbps in Fast mode

. It con-

sists of two lines, the serial data line I2CDAT and the serial clock line I2CCLK. The module acts

as a single master device, e.g. the clock I2CCLK is driven by the module. I2CDAT is a bi-direc-

tional line. Each device connected to the bus is software addressable by a unique 7-bit ad-

dress, and simple master/slave relationships exist at all times. The module operates as master-

transmitter or as master-receiver. The customer application transmits or receives data only on

request of the module.

The I

C interface can be powered via the V180 line of EHS5-E/EHS5-US. If connected to the

V180 line, the I

C interface will properly shut down when the module enters the Power Down

mode.

Note: Good care should be taken when creating the PCB layout of the host application: The

traces of I2CCLK and I2CDAT should be equal in length and as short as possible.

2.1.8 PWM Interfaces

EHS5-E/EHS5-US offers two PWM (Pulse Width Modulation) interfaces, which 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.

2.1.9 Status LED

The GPIO5 line at the SMT application interface can be configured to drive a status LED which

indicates different operating modes of the module (for GPIOs see Section 2.1.6). GPIO and

LED functionality are mutually exclusive.

Table 2: GPIO assignment

GPIO PWM Status LED

GPIO5 Status LED

GPIO6 PWM2

GPIO7 PWM1

GPIO8

1. The I

C functionality will be available as of Release 2.