Thursday, April 29, 2010

Introduction to APR9600

In our last post we discussed on how to monitor Saline level using an LDR, now let us move to the APR module. Before going to the interface part of APR 9600 with the microcontroller, lets look about APR9600 in brief.

The APR 9600 is a 28 pin device used to record and playback maximum of 8 messages. The APR9600 device offers true single-chip voice recording, non-volatile storage, and playback capability for 40 to 60 seconds. The device supports both random and sequential access of multiple messages. Sample rates are user-selectable, allowing designers to customize their design for unique quality and storage time needs. Integrated output amplifier, microphone amplifier, and AGC circuits greatly simplify system design. The device is ideal for use in portable voice recorders, toys, and many other consumer and industrial applications.

Tuesday, April 13, 2010

Saline Level monitoring using LDR

Hi folks, we are looking into one of my project "EMAS - Wi Tech", In our previous post we saw some introduction about it. Now we are going to dig further on the different sensor circuits used. The first one which we would see is how we monitored the saline level using an LDR, Just go through the below para for detials on the circuit what we used.

The LDR sensor circuit consists of a comparator, an LDR and a pair of multi-turn preset resistor (10k ohm). The LDR is connected in series with a preset resistor forms a voltage divider configuration. When no laser beam falls on the LDR its resistance will be very high compared to 10k ohm. So by voltage divider rule small voltage will be available across the preset resistor. But when laser beam falls on the LDR its resistance becomes almost zero. So voltage across the preset will become nearly 5V. This change in voltage across the preset can be detected using a comparator. Comparator is constructed using UA741.
The threshold voltage can set using another 10k ohm preset connected to the inverting input of the opamp.
In normal condition output of comparator remains at logic zero because the laser beam is distracted by the saline present in the bottle, but when saline level reduces, the distraction is lost and the laser beam falls on the LDR, because of this comparator output changes to logic one. This change is used by microcontroller to detect the quantity in the saline bottle.

Sunday, April 4, 2010

Introduction to EMAS-Wi Tech

Hi guys last week we were looking on brief into one of my project "Emergency Announcement System In Hospital Using Wireless Technology" which I have abbreviated as "EMAS-Wi Tech". It is now time to look into it in detail. This post will explain the outline of the project and the components used. Just look at the below block diagram which describes the outline of our project.

In the Transmitter side, The Output from the sensors are continuously monitored by the microcontroller, when the microcontroller senses any abnormal values, it transmits corresponding data through wireless medium with the help of the ZigBee module. On the Receiver side, the wireless data obtained by the ZigBee module is sent to the Microcontroller, The microcontroller then analyses the data obtained from the ZigBee module and triggers corresponding messages signals to the APR module. The APR module playbacks corresponding voice recorded signals according to the message signals obtained from the microcontroller.

P89V51RD2, an 8051 Microcontroller is the Main component at the Transmitter side, which is used to sense the output from the Sensors. The Saline Level is sensed using an LDR sensor unit. XBee PRO is used in the ZigBee module at the Transmitter and Receiver sides. PIC16F877A is used at the Receiver side, which senses the output from the ZigBee module. APR9600 is used to playback recorded voice signals based on the input from the Microcontroller.