Batwatch is a simple monitor for a solar panel battery charger, using an Atmel ATtiny13V. It periodically measures the charge current and battery voltage, and shows them by blinking two LEDs. I built this circuit into the plug of a VW solar charger panel that is used to prevent a discharge of the battery when a car is not used for some time. A modern car contains a large amount of electronics, and a quiescent current of 40-50mA (about 1Ah per day!) is considered "normal".

When the device is connected to the computer, a Virtual COM Port (VCP) will be created. This is shown at the Device Manager Window under Ports(COM & LPT). In this case, COM5 was created when the PIC18F4550 was attached to the USB Port. It may be interesting to note that if you plug in your PIC in different USB ports, the VCP created will be different.

This is the transmitter PLL module with ATMega8, MC145170 and 16x4 LCD Display.

The quickest way to display something is probably sending the data to the computer to be displayed on the monitor. One of the ways to do this is to use the USART module on board the PIC Microcontroller by making use of the pins RC6 and RC7 which is also the TX and RX pins respectively when the SPEN bit on the RCSTA register is set.

This is 50 MHz frequency meter / counter for measuring frequency from 10Hz to 50 MHz with 10 Hz resolution. It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc. The meter provides very stable readings and has excellent input sensitivity thanks to onboard amplifier and TTL converter, so it can even measure weak signals from crystal oscillators. With the addition of prescaller it is possible to measure the frequency of 1GHz and above.

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