NSF-Funded Student Design Projects:

ETL Clock Reminder

Designers: MultiSemester see Student Teams Table
Client Coordinator: Registered Nursing Supervisor, St. Anne’s Mead
Supervisors: Dr. Robert Erlandson, Mr. David Sant
Department of Electrical and Computer Engineering
Wayne State University
Detroit, MI 48202

Multi-Semester Project Student Teams

Introduction

The ETL Clock Reminder is designed for elderly individuals who are starting to experience memory loss due to dementia, early stages of Alzheimer’s disease, or other age related conditions. The device serves as a talking clock, with a large time display and a reminder system that provides verbal as well as visual alarms and prompting. A family caregiver or staff attendant sets the time alarms, reminder configurations, and prompting messages.

St Anne’s Mead is a residential Assistive Care facility. A substantial number of its clients, while living independently in their own apartments, need to be reminded about meal times, daily events, and taking medications. The residents do not like to be a “bother” and generally seek technology and strategies to remain as independent as possible. The facility has tried a variety of talking clocks and reminder systems, but all have limitations.

The Clock Reminder was designed for high reliability. While it may have been possible to write a custom application to run on commercially available Pocket PCs or PDAs these devices are neither reliable nor consistent enough to be used for this application and they often can not produce audio messages with sufficient volume. The ETL Clock Reminder overcomes these limitations by utilizing dedicated electronics designed specifically to meet project requirements.

The ETL Clock Reminder was designed based on staff and resident input. It is a relatively sophisticated device and was scheduled as a two-semester project. Due to a number of technical reasons, the project was not completed within the two-semester period. This paper describes work to date.

Overview of Functional Specifications:

When it is necessary to change the configuration or alarm settings, a pinhole switch on the back of the unit activates the program mode. This is done to prevent inadvertent setup changes and to keep the display free from complex menus. The ETL Clock Reminder was designed to be easy to setup and use. A graphic LCD display quickly conveys all necessary information to the user via text and icons. To set the alarm times and messages a simple menu structure was designed to walk the user through entering alarm events, times and the associated voice recording. The Clock Reminder menu uses a simple scroll wheel and button combination to make all settings. Alarm acknowledgement is done with the press of a single button that illuminates when the alarm is activated.

The ETL Clock Reminder consists of several key components. See Figure 1. The Clock reminder utilizes a 128 by 64 pixel display with a viewing area of 66.8mm(W) by 35.5mm(H). The display is of the transmissive type with a yellow-green backlight. A ambient light sensor is utilized to automatically adjust the display brightness to make it easy to read in any lighting condition. The display communicates to the host processor via a dedicated eight-bit parallel bus.

Figure 1. ETL Clock Reminder Functional Diagram

The graphics display is much more versatile than character-only displays as custom icons and large digits can be displayed. A scaled sample image of a typical display can be seen in figure 2. The Character fonts and Icons are stored in a external 64K serial EEPROM.

Figure 2. Sample Display Image

In addition to a visual indication of time and alarm events, the ETL Clock reminder can announce the time or alarms using a recorded voice message. The unit can record up to 120 seconds of audio utilizing an ISD4200 Series Chipcorderâ from Winbond. This audio reproduction method is preferable since the recorded audio can be in any language and can be from a recognized source – for example that of a teacher or family member. The system has an internal speaker and amplifier.

The actual time and alarms are stored on a battery backed real time clock (RTC) IC that has a built-in calendar. The component used is a Dallas Semiconductor DS1305 IC.

Power for the device comes from an external wall cube type adapter or from internal Ni-MH batteries. To safely charge the batteries a charge controller IC, (bq2002C) from Texas Instruments is utilized. Over current and over temperature conditions are monitored and corrected. Regulated power for the clock is via a high-efficiency switching regulator.

The Microcontroller utilized for the project is a Microchip PIC16F877. The Clock code is programmed using the C language for maximum flexibility. The PIC 16F877 was chosen for its flash programming capabilities, presence of required peripherals, and availability. Peripherals used include the SPI port for communicating with the clock, voice, and memory ICs. The PICs internal analog-to-digital converter inputs are used to monitor the light level and battery voltage while the parallel port interfaces to the display.

The entire clock circuit fits on a two-sided printed circuit board (PCB) measuring 50mm x 92mm. Most of the components on the PCB are surface mount types to keep the size of clock to a minimum.

Remaining Tasks:

The remaining tasks include debugging the oscillator circuit used in the RTC circuit to correct an instability issue, finishing the clock software, and fabricating the enclosure. The oscillator instability issue may involve a PCB layout change. The software items to be resolved include finishing the display driver code as well as finishing the code to display large characters on the display. The general clock reminder and recording software also needs to be written and debugged. The mechanical fabrication of the enclosure needs to be done for the final packaging to be complete.