http://www.sparkfun.com/products/9484

maybe good for a beginner?

I totally don't get how to do this with a serial LCD... I'm not declaring an lcd or using the lcd library therefore, the lcd.createChar(0, newChar); does not work...

*edit* after reading through some much older posts... It looks as if the serial LCDs requires you to write special characters to it and you only have room for 8 custom characters. It appears to be much more work than its worth.

Hey guys,

I'm looking for a simple way to show battery power and you guys seem to be good at the LCD stuff.

I'm using a sparkfun serial LCD and would like to show the battery life as a bar (one block on the LCD) where a dead battery will have one horizontal bar in a block (an underline cursor, I guess) and a full battery would be a full block (like a non-blinking box cursor). Is there an easy way to get this done? I know that the serial LCDs are a bit different with the code (I am not using a library).

Thanks a lot!

-Rob

For those who are reading... Amazingly, the pin is still functioning correctly!!!

It's a car oil pressure sensor 

FYI Autometer Model 2242, 100 PSI. It's resistance is 250 ohm @ 100 psi -> 30 ohm @ 0 PSI.

The voltage divider was as follows:

9v --- 250 ---- Vout ---- 250(pressure sensor) --- Grnd

So the 9v had a 250ohm resistor in line prior to the analog pin.

I used 9v to get a larger range on the ADC, however, I'm sure I could have used a lower voltage.

If the arduino was not reading that analog pin, is the circuit still complete?

I was working on a project before I left for work and powered it up and did not have one resistor (a pressure sensor) connected to a leg of a voltage divider. Now I’m sitting at work and realized that I sent 9V to an analog pin!!! It was turned on and off for few short periods of time (30 seconds or less) and the program in the Arduino was not looking for a signal at that pin. I’m worried that when I get home, I’ll find that I cooked the A0 pin on the uno.

Three quick questions:

I know that it does not take more than a split second of high voltage on the IC to ruin it, but what are the chances that it will be ok?
If I did not cook that input, will it be reliable or should I just use a new pin?
If I DID cook it, will it affect all of the ADC pins?

Right now I’m SO mad at myself for forgetting to plug that sensor in and can not believe that I totally zoned out on the fact that 9V was being fed to an analog pin.

 

I have multiple sensors (flow and pressure) and did not want to draw to much current through the Uno, so on my power supply I have 9 volts feeding the Arduino and wanted to pull the power directly from the supply. I can simply add a 5v power reg and be done with it but wanted to make sure that I could not use 9v before doing extra work.

Thank you.

Hey guys,
   I’m planning on using two Seeed Studio water flow sensors for a project and have a few questions about the output signal on the sensor.

The data sheet states that the output signal voltage will be 4.5v at an input voltage of 5v. Is it safe to assume that the output voltage will be proportionately higher at 9v input voltage?

Also, what is the highest voltage that can safely be placed on a digital input pin (without blowing up my board!!! lol)

FYI, I’m using an Arduino Uno.

Data sheet

http://garden.seeedstudio.com/index.php?title=G1/2_Water_Flow_sensor

Thank you sir!

I was trying to skirt around using a MOSFET because I had a NPN laying in the box and a MOSFET would require a trip to the store... LOL.

I'm not sure if its even worth the trouble. The circuit will only draw .002A at 12V...

Whoa!!! Good catch! Lucky I was testing this on a breadboard without connection to the arduino. I had the NPN up stream of the voltage divider and was getting 1.65 at Vout (High) and 0 at Vout (Low). I got confused as to why the voltage was so low so I thought to put it downstream.

Any idea why I was losing so much voltage through the NPN?

I'm using a voltage divider to change 12v in to 4.3 volts out to monitor battery voltage. The voltage divider seems to be working properly.

I'm using a 2n4401 NPN as a switch so that I'm not draining power through the voltage divider (even through it would be a low draw anyway, I'm using 3.3k/2k as R1 + R2 on the divider).

When I measure voltage on the v out while using the NPN, High state voltage = 4.19 (close enough), Low state voltage = 0.80.

The NPN is between R2 and GND, the Base has a 1k resistor between B and the +5v

If the NPN is at low(off) why I'm I getting a voltage? Any clues?

I just thought of something.

What if I printed 4 spaces just before the printing of the pressure?

  selectLineTwo();
  delay(500);
  Serial.print("PSI= ");
  goTo(24); //6th space on 2nd line
  Serial.print("    ");
  goTo(24);
  Serial.print(pressure);


Would this work or look delayed and slow?

I have a program that monitors water pressure and displays it on a sparkfun 16x2 serLCD. The pressure value is updated every 500 milliseconds. All is well if the display shows 0-99, but when the pressure reaches 100 and decreases back to 99, the “ones” digit does not clear so the display reads “990” for 99. It will do this when any value takes up more spaces then the next value.

For example:
It will print “this is a test”
Then “good”

The display will read “good is a test”

I can use the clrLCD command but then I have to reprint all of the other information on the screen

Any ideas?

Thanks!

I connected a ground (quickly) before I went to work.... I was getting the right voltage reading from the serial.print and that looks to have sovled the problem. I'll know more tonight when a run the sensor through the range of pressure but it's looking promising!

Thank you very much for the tip!!!!!

-Rob