3 replies to this topic

[bx_bob]

Hello everyone!
I'v got a board like this:
http://www.nuelectro...ia_3310_lcd.pdf
and the arduino code... acording to the difference of voltage(arduino 5v -> netduino 3.3v),
i still stuck in using the joystick.

public static readonly int[] adc_key_val = new int[] { 50, 200, 400, 600, 800 };

the numbers are from arduino.
so all i need is recalculate these 5 value, from 5v to 3.3v? am i right?

thanks.

[NooM]

i suggest not putting 5v into the 3.3v analog pins.

[bx_bob]

After a lot of test. i found the up key can't be detected. weird. Is it means 3.3v not enough to drive it?

[teo]

The joystick output is an analog output that ranges from 0 to 5V, depending on direction (the Vcc for the resistor ladder is tied to 5V). If you compute the analog values for SW1 positions 1,2,3,4,6, the outputs will be 0.000 0.235 0.720 1.434 3.573 volts, respectively, or 0 73 223 445 1109 bits > maxed out, try 1023 Hence, there is a chance that you will slightly exceed the 3.3V limit of the Netduino ADC. You might be able to get away with it, but this is not recommended. Also, note that the joystick feeds AD0 with 5V when nothing is pushed. If I am not wrong, the digital pins are 5V tolerant, but not so for the analog pins.