USB ESR Meter Circuit The main part of the meter is a ATmega8 microcontroller that controls the entire device. Its main the task is to process measured data and perform calculations so that the... Electronics Projects, ATmega8 FT232R USB ESR Meter Circuit
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USB ESR Meter Circuit The main part of the meter is a ATmega8 microcontroller that controls the entire device. Its main the task is to process measured data and perform calculations so that the result is real ESR value. This value is displayed on the LCD. Another task of the ATmega8 microcontroller is communication with a USB controller that then communicates with a computer, that is sends measured data and allows the meter to be controlled via the computer.
The requirements of the A / D converter in this particular application, ie the ESR meter, are not at all critical for the transfer time. There is no need for a high-speed converter, it will also be slower, which will also result in greater accuracy, which is for the application important (ESR meter does not need to measure ESR value many times per second, it is enough once per second, but accuracy is important). Another important parameter converter is a resolution. This depends on the desired measuring range of the meter. The advantage is using a multichannel converter, when it is possible to measure other than ESR quantities. A typical example is the measurement of the battery voltage, which can be used to monitor the rate of discharge.
FT232R Communication via USB has been selected for communicating the meter with the personal computer protocol. Simply because this interface is based on virtually everyone computers, unlike today’s extruded parallel or serial ports. The USB interface is also much more resistant to disturbances than the parallel port, for example to use as a 5 V supply.
For this reason, it was decided to use the FT232R circuit whose datasheet can be used found on. This is a USB protocol converter to a serial UART. On the side of the computer the circuit can communicate via the USB 2.0 version 2.0 speed to Full Speed, that is, up to 12 Mbit / s. The circuit communicates across the device (microcontroller) via serial protocol, that is, using the wires for receiving and transmitting serial data (RxD and TxD).
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