Where on earth will this be used?
A 100 mA x 5V PV (= photovoltaic = solar) cell is not a small item compared to many items of portable equipment.
A modern highish efficiency crystalline PV panel will give you about 10 mW/cm^2 actually delivered in full sun.
So for 5V x 100 mA = 500 mW output you will need about 50 cm^2.
You can connect this via a diode directly across a suitable battery, or via a regulator to a load of your choice. If you connect directly to a battery then you may wish to provide overvoltage regulation. This is easy and cheap and can be discussed if your application sounds like that approach may be useful.
A 9V Alkaline "PP3"size (transistor radio type) battery is NOT intended to be recharged. You could arrange the panel so that it sup[plies load current when it is able to do so, but does not do so, or you could arrange it so it can power the equipment directly when illuminated adequately and the load is active BUT can also charge the battery. Alkaline batteries are NOT intended by their manufacturers to be recharged in most cases BUT a degree of recharging is in fact possible. Charging efficiency is limited, lifetime cycles are poor compared to eg NimH, and overcharge control would be needed. This is a nonstandard application so you would need to be aware of possible problems.
Use of a small rechargeable battery in combination with the main battery could be useful. Charge control is easy and cheap.
Parallel vs Serial
When you use LiquidCrystal library you have to tell it the GPIO pins that are used to connect to the display. There are two control connections and a 4-wire parallel data connection.
However, the LCD display on your E-term communicates using a TTL-level serial link, not a parallel GPIO link.
Easy to use LCD display and Keyboard decoder combo that integrates with any controller circuit. The LCD can display up to 80 alphanumeric characters at a time in 4 lines x 20 characters arrangement. The keypad consists of a 0-9 numeric keypad and 6 user defined function keys. Communication with the host is via serial port operating at TTL level.
You can't drive your E-term using LiquidCrystal library.
Your diagram is small but it shows TX and RX connected to the Eterm, not a set of 6 GPIO pins.
Note that, in most Arduinos the same TX and RX are used for USB communication with the Arduino IDE software on your PC. To transfer compiled sketches to the GizDuino+. So you may need to switch the RX connection between USB and E-term somehow. AT least disconnect RX from your E-Term when using the IDE to program the GizDuino+.
Power
The E-term description says
Power Input: 8-12V
Display : 4x40 LCD
Input device: 0-9 numeric keypad and 6 user defined function keys
Note that it requires a minimum of 8V. Your diagram shows the E-term Vin connected to the GizDuino+ Vin pin. This wont't supply 8V if you are powering your Gizduino from the USB 5V supply. You need to power the combination from an off-board supply of between 8 and 12 volts (e.g. 9V 1A wall-wart or battery)
Conclusions
I'd
- Ensure the E-term has it's 8-12 V supply connected to a supply of that voltage.
- Set the serial comms speed to the data rate in the E-term manual.
- use Serial.print() not LiquidCrystal.print() etc.
e.g.
void setup()
{
// initialize the serial communication:
Serial.begin(9600);
// send text to E-Term
Serial.println("Hello E-term...");
}
void loop() // run over and over again
{
Serial.print("*");
delay(1000);
}
Best Answer
The power supply input goes to a 7805k regulator which feeds the MCU. The 78xx regulators need about 2 to 2.5v higher input than the rated output to work properly .
My guess is that the regulator was able to work correctly while the battery was full and stopped working as soon as the battery voltage dropped to 7v or so.
Also note that the datasheet of you device specifies an input voltage range of 8-12v for the power supply input, so the input you are trying to use is out of spec.