APPLICATION NOTE GR/GS64 General Purpose and Alternate Function I/O. Reference: WI_DEV_Gx64_APN_008 Revision: 001 Date: 2006/12/15

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1 Reference: WI_DEV_Gx64_APN_008 Revision: 001 Date: 2006/12/15

2 The information contained in this document is the proprietary information of Wavecom Inc. The contents are confidential and any disclosure to persons other than the officers, employees, agents or subcontractors of the owner or licensee of this document, without the prior written consent of Wavecom Inc, is strictly prohibited. Further, no portion of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, without the prior written consent of Wavecom Inc, the copyright holder. First Edition (December 2006) Wavecom Inc publishes this manual without making any warranty as to the content contained herein. Further Wavecom Inc reserves the right to make modifications, additions and deletions to this manual due to typographical errors, inaccurate information, or improvements to programs and/or equipment at any time and without notice. Such changes will, nevertheless be incorporated into new editions of this manual. All rights reserved. Wavecom Inc, 2006 Publication number: Printed in US Page: 2/13

3 Table of Contents 1 Introduction LOGIC INTERFACE VOLTAGE GPIO vs. Alternate I/O Functions DEFAULT SETTINGS AT*GPIO OR ALTERNATE FUNCTION SELECTION Using GPIO USING GPIO FOR CONTROL USING GPIO FOR MONITORING Using Alternate I/O functions UART 1 MODEM CONTROL ACTIVITY INDICATION SD/MMC SUPPORT I2C SUPPORT Appendix A -- I/O Pins by GR/GS64 Device Type Page: 3/13

4 1 Introduction The GR/GS64 family of Wireless CPUs is designed to provide a rich and flexible set of physical interfaces. These interfaces allow the application designer to integrate GR/GS64 Wireless CPUs into the widest possible variety of applications and still meet cost, power and size constraints. GR/GS64 general purpose input and output (GPIO) pins represent the simplest of digital interfaces single line digital signals. GPIO pins can be used to control or monitor devices such as relays, contacts, actuators and lamps with appropriate signal conditioning. GR/GS64 Wireless CPUs provide as many as thirty-three GPIO pins. GR/GS64 Wireless CPUs also provide up to three analogue-to-digital converters. These convert analogue voltage levels to digital measurements. With appropriate transducers, applications can use the measurements to monitor a wide variety of physical conditions like temperatures, pressures or fluid levels. 1.1 Logic Interface Voltage All GPIO interfaces are referenced to the voltage level available on system connectors VREF-pin, unless otherwise is stated in the units Integrators Manual. GR/GS64 Wireless CPU type VREF Direction VREF Voltage Level GS64 Output from Wireless CPU 1.8V GR64001 Output from Wireless CPU 2.8V GR64002 Input to Wireless CPU 1.8V 5.0V Under no circumstances can a logic signal exceed VREF. Level translators must be incorporated if the application logic voltage is different than that of the Wireless CPU. Failure to heed to this requirement can lead to unexpected behaviour and may permanently damage the Wireless CPU. Examples of possible level translators to use consist of, but are not limited to: Maxim ST MAX3000 family ST2378E Page: 4/13

5 2 GPIO vs. Alternate I/O Functions Many of the GPIO pins can be configured to perform dedicated operations such as activity indication, modem control, SD/MMC memory support or I 2 C. These dedicated operations are known as alternate I/O functions. While the number of GPIO and dedicated tasks that can be active simultaneously is limited by this technique, the Wireless CPU size, power consumption and pin count are kept small with no decrease in flexibility to meet application requirements. Section 3 describes how to use and control GPIO pins. Section 4 describes available alternate I/O functions. 2.1 Default Settings The factory default setting of all IO s is as input signals and pulled up. If a signal is changed by the application and stored with AT&W the change is stored so that the next time the Wireless CPU is powered up the IO will maintain the new customer setting. 2.2 At*GPIO or Alternate Function Selection The integrator should understand that the use of a pin for GPIO or an alternate function is exclusive. If an attempt is made to issue GPIO commands on a pin that is enabled for an alternate I/O function, the GPIO command will return an error indication. When the alternate function has been disabled, GPIO commands may once again be issued without error on the pin. Please consult the table in Appendix A for the GR/GS64 Wireless CPU type that is used. Each table describes the pins available for GPIO use and indicates if a pin is part of an alternate function. Select pins for GPIO that do not belong to an alternate function that is also needed. For example, suppose that two GPIO pins are needed in a GR64 application, one to monitor a contact closure and another to control a relay. The application must also minimize power consumption, so the GR64 will be placed in standby mode periodically. Standby mode requires the use of the modem control lines which are an alternate function of the GPIO7-GPIO12 pins. Therefore, do not select the monitor and control pins from the GPIO7-GPIO12 group. In this example, we select GPIO1 to monitor the contact closure and GPIO2 to control the relay. Page: 5/13

6 3 Using GPIO 3.1 Using GPIO for Control GPIO pins are configured and controlled in software using the E2IO AT command. See the GR/GS64 AT Command Manual for a complete description of the E2IO command. To continue our example, the relay is controlled from the GPIO2 pin. From Table 2 in Appendix A, the E2IO signal name for GPIO2 is IO2. To control an external device using a GPIO, configure the pin for output then set the desired level. AT*E2IO=2, IO2,1 AT*E2IO=1, IO2,1 (configure GPIO2 for output) (assert GPIO2) The application can query the level of a GPIO pin, whether configured for input or output. AT*E2IO=0, IO2 *E2IO: 0,"IO2",1 (pin level is high) The application can also query whether a pin is configured for input or output. AT*E2IO=3,"IO2" *E2IO: 3,"IO2",1 (GPIO2 is configured for output) The configured direction of GPIO pins is saved in the profile. If the application saves the profile using AT&W command, the pins will be configured on subsequent Wireless CPU start-ups according to the directions set when the profile was saved. However, the external circuitry should be designed to act benignly if the control signal is not present or is configured for input. In this example, the application should select either the normally open or normally closed outputs of the relay to provide a benign start-up state. Page: 6/13

7 3.2 Using GPIO for Monitoring The contact closure is connected to GPIO1. From Table 1 in Appendix A, the E2IO signal name for GPIO1 is IO1. Configure the GPIO1 pin for input. AT*E2IO=2,"IO1",0 The application can query the level of a GPIO pin, whether configured for input or output. AT*E2IO=0, IO1 *E2IO: 0,"IO1",0 (pin level is low) Querying the level of a GPIO pin repeatedly can be wasteful, so the application can program GPIO pins as input triggers. When a pin is configured as a trigger, a change in the pin s level will cause a report to be issued on the AT command interface. Configure the GPIO1 pin as an input trigger. AT*E2IO=4, IO1,1 Now any changes in the level of the GPIO1 signal will cause a report. *E2IO: 4,"IO1",1 This technique can be quite useful in low-power applications. The Wireless CPU can be placed in standby mode and will awaken when a transition on a pin configured as an input trigger occurs. The application can query if a GPIO pin has been configured as an input trigger. AT*E2IO=5,"IO1" *E2IO: 5,"IO1",1 The input trigger feature can be disabled for a GPIO pin. No reports will subsequently be issued when a level change occurs on that pin. AT*E2IO=4, IO1,0 Page: 7/13

8 4 Using Alternate I/O functions The following sections describe the alternate I/O functions provided by GR/GS64 Wireless CPUs. 4.1 UART 1 modem control The UART 1 modem control alternate function provides full RS-232 modem control signals. Some of the reasons to select UART 1 modem control alternate function are: Flow control is typically required to prevent serial buffer overruns when highspeed UART data rates are used. Modem control enables the RTS/CTS hardware flow control mechanism. If standby mode is required for low power consumption, DTR and DSR are used for sleep/wake handshaking. The Ring Indicator signal can indicate receipt of incoming calls or messages. Plug-and-Play enumeration of serial devices requires modem control lines. If the application is using the Windows driver to control GR/GS64 Wireless CPUs, the UART 1 modem control alternate function must be enabled. By factory default, the UART 1 modem control alternate function is selected. The alternate function is disabled or enabled by using the *E2RS232 AT command. AT*E2RS232=2 (disables UART 1 modem control) AT*E2RS232=0 (enables UART 1 modem control) The *E2RS232 settings are not retained across power downs. If the application wishes to disable the UART 1 modem control alternate function, it must do so after each Wireless CPU restart. The application may then use the modem control pins for GPIO purposes. Page: 8/13

9 4.2 Activity Indication The LED signal can display Wireless CPU activity when its alternate function is enabled. This signal has historically been connected to an LED to provide a visual indication of Wireless CPU activity. The following table describes the activity indications if an LED is connected: LED indication Off On, steady Slow flashing Quick flashing Description Wireless CPU not powered on. Power is applied but the Wireless CPU is not registered on the network. Corresponds to CREG conditions 0, 2, and 4. The Wireless CPU is registered on the network. Corresponds to CREG conditions 1,5. The Wireless CPU has received an SMS message within the last 10 seconds. Slow flashing is characterized by a 30 ms pulse with a 2-second period. Quick flashing is characterized by a 200 ms on pulse with a 400 ms period. The quick flashing lasts for 10 seconds after the last SMS message was received. The activity indication alternate function for the LED signal can be enabled or disabled using the *E2LED AT command. AT*E2LED=1 (enables LED activity) AT*E2LED=0 (disables LED activity) The LED activity indication function selection is saved in the profile. The current selection can be retained across power downs if the AT&W command is used to save the profile to non-volatile storage. 4.3 SD/MMC support The GS64 Wireless CPU can act as either a secure digital (SD) or multimedia memory card (MMC) bus host. I/O pins GPIO25-GPIO33 are currently permanently configured for the SD/MMC alternate function and cannot be used as GPIO pins. Page: 9/13

10 4.4 I2C Support The GR/GS64 Wireless CPU can act as either an I2C or GPIO interface. I2C can be enabled or disabled using the AT*E2I2C AT command. AT*E2I2C=1 (enables I2C) AT*E2I2C=0 (disables I2C) Page: 10/13

11 Appendix A -- I/O Pins by GR/GS64 Device Type Table 1. GR64 I/O pins GR64 Function AT*E2IO Alt function GR4x Pin Primary Sig GPIO <io> section Equivalent 21 GPIO1 GPIO1 IO1 GPIO1 22 GPIO2 GPIO2 IO2 GPIO2 23 GPIO3 GPIO3 IO3 GPIO3 24 GPIO4 GPIO4 IO4 GPIO4 13 ADIN4 GPIO5 IO5 GPIO5 33 LED GPIO6 IO6 4.2 GPIO6 32 DSR1 GPIO7 IO7 4.1 GPO3 36 RI GPIO8 IO8 4.1 GPO2 39 RTS1 GPIO9 IO9 4.1 GPIO9 37 DTR1 GPIO10 IO GPI1 38 DCD1 GPIO11 IO GPO1 40 CTS1 GPIO12 IO GPO4 29 SDA GPIO13 IO SCL GPIO14 IO TD3 GPIO7 44 RD3 GPIO8 Page: 11/13

12 Table 2. GS64 I/O pins GS64 Function AT*E2IO Alt function Pin Primary Sig GPIO <io> section 40 GPIO1 GPIO1 IO1 41 GPIO2 GPIO2 IO2 43 GPIO3 GPIO3 IO3 44 GPIO4 GPIO4 IO4 45 SDA GPIO5 IO SCL GPIO6 IO GPIO7 GPIO7 IO7 50 GPIO8 GPIO8 IO GPIO9 GPIO9 IO9 53 RI GPIO10 IO DCD1 GPIO11 IO DTR1 GPIO12 IO DSR1 GPIO13 IO RTS1 GPIO14 IO CTS1 GPIO15 IO KEYROW1 GPIO16 IO16 84 KEYROW2 GPIO17 IO17 85 KEYROW3 GPIO18 IO18 86 KEYROW4 GPIO19 IO19 87 KEYROW5 GPIO20 IO20 88 KEYCOL1 GPIO21 IO21 89 KEYCOL2 GPIO22 IO22 90 KEYCOL3 GPIO23 IO23 91 KEYCOL4 GPIO24 IO24 74 MMCCLK GPIO25 IO MMCCMD GPIO26 IO MMCDAT0 GPIO27 IO MMCDAT1 GPIO28 IO MMCDAT2 GPIO29 IO MMCDAT3 GPIO30 IO MMCCMD_EN GPIO31 IO MMCDAT_EN GPIO32 IO MMCDAT_EN0 GPIO33 IO Page: 12/13

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