Analog on the Arduino

int k; // integer = 16 bitsk = analogRead(1);

Analog volts value (0V → 5V)returns from 0 to 1023 into “k”

(10 “bits” = 1024 values)

Analog range:

● dynamic range● precision● accuracy – repeatability● calibration for accuracy?

Resolution

2 bits 0 - 3

8 bits 0 – 255

10 bits 0 – 1023

16 bits to 65000

32 bits to over 4 billion

Resolution / precision

5 volts

1024 possible measurements

So resolution = 5000 / 1024 millivolts

Ie about 5 mV

● Pullups and Voltage Dividers

READING REFERENCE DOCUMENTS

LDR

THERMISTOR “NTC”

LM35 Temp SENSOR

LDR

“50k OHM Thermistor NTC 3950 MF52AT”

Accurate temp sensor LM35

But analog sensor resolution could be better matched than this

● Modulo division – remainders

● Long integers – preventing rollover errors

PWM to LEDs(remember that?)

PWM output (dimming a LED) used

analogWrite(3, 150); // pin d3, 150/255 bright

This was “8 bit” resolution (0 - 255)

Industrial

Common industrial analog signalling has been

4 – 20 mA full range.

How could Arduino handle that?

Why start from 4 mA, not 0mA?