Also an automatic recharge circuit is implemented in the IC. The battery can not be overcharged, the MCP73833 has an end-of-charge control circuit inside. A resistance of 10 k Ω represents a thermistor at 21 ◦ C. The battery used in our design doesn’t have a thermistor inside so R 4 is used to mislead the battery-charger. By measuring the resistance of this thermistor, the charger can lower the charge current when the battery becomes too hot. Some batteries have an integrated thermistor.
![battery pulse charge circuit for use with standard charger battery pulse charge circuit for use with standard charger](https://sc01.alicdn.com/kf/HTB1H26vXxHBK1JjSZFvq6yKtXXau/15203/HTB1H26vXxHBK1JjSZFvq6yKtXXau.jpg)
To use this feature extra hardware needs to be implemented on the tag. Default USB 2.0 ports can also deliver 500mA, but this needs some digital negotiation. This value is chosen so that it is possible to charge the tag from any standard USB 2.0 port, some motherboards power down the USB port if the current given by the port is to high. A 10 k Ω resistor ( R 3 ) is used to limit the charge current to a maximum of 100 mA. A green LED lights up when the battery is fully charged, the yellow LED lights up when the battery is charging. In the prototype of the tag two LEDs are integrated. Figure 2 shows the circuit arround the MCP73833. Another advantage of this IC is that it needs a low number of external components. This IC is a good choice because it makes it possible to charge the battery by using 5 Volt (e.g. The MCP73833 is an Inte- grated Circuit (IC) with an Lithium-Ion and Lithium-Ion Polymer charger inside. Because we use a Lithium-Ion Polymer battery, a specific charger is needed. To charge the battery, we implemented a charger in the tag. The battery has a nominal capacity of 1300 mAh and an output voltage between 3.0 Volt and 4.2 Volt. In this design a Lithium-Ion Polymer battery is used. A battery with a high energy density is used so the physical dimensions can be small.
![battery pulse charge circuit for use with standard charger battery pulse charge circuit for use with standard charger](https://i.pinimg.com/originals/4c/9a/45/4c9a4518a949559ac4364938dd95f90c.jpg)
Good design starts with finding components which are energy efficient. To increase the time between two battery recharges, power consumption is one of the major design issues. The tag uses a rechargeable battery for powering the circuits. The GSM and Wi-Fi module are powered via the 3.3 voltage step down convertor. The battery voltage is measured by the Wi-Fi module via a sensor input. A Li-Po battery powers the GPS module and the 3.3 voltage step down converter. Three LEDs and some control lines for the GPS and GSM module are connected as normal GPIO. It is also connected to multiple sensors (e.g. The Wi-Fi module is used as main controller, it is connected with the GPS and GSM module via UART. An overview of the hardware can be seen in the block diagram on Figure 1. The conclusion over the multi technology tag can be found in Section 7. Some use cases and other possibil- ities with the same hardware are listed in Section 6. Section 5 contains information about the power consumption used by the different modules and circuits.
![battery pulse charge circuit for use with standard charger battery pulse charge circuit for use with standard charger](https://1.bp.blogspot.com/-wSbzxvdwSXw/USyM01yPQjI/AAAAAAAACT4/ooSpg0sYtC4/s640/135-10259.png)
#Battery pulse charge circuit for use with standard charger software#
The software design is explained in Section 4. Section 3 discusses different ways to do localization and data transmissions. In Section 2 the hardware design of the tag is explained. This data can also be used to calculate the coarse position of the tag. If the tag is unable to receive a valid GPS-signal, the tag can make use of the received signal strengths from GSM base stations. While moving indoors, it could be possible that the tag switches from GPS localization to Wi-Fi localization for tracking and from GPRS to Wi-Fi for communication with the server. The tag is designed to automatically switch to other technologies when changing from one environment to another. The goal of ”the Multiple Technology Tag” is to com- bine existing technologies and create a device that can locate people and objects in any given environment. GPS only works when enough satellites are detected). Nowadays, there are already a number of localization technologies (based on GPS, Wi-Fi, GSM, UWB, etc.) which perform well, but they all have one problem: they only work when they are used in a specific environment or application (e.g. One of the shortcomings in the total integration between environment, humans and computer-based technologies is the localization of people and objects. In the near future, it is likely that the need for computer- integration will rise to even higher levels. present, many objects in our environment are connected in some way to computer-based technology.