AVR Library Command Reference

Reference

C++ and Arduino methods are shown in red.

C functions are shown in green.

static void PololuWheelEncoders::init(unsigned char a1, unsigned char a2, unsigned char b1, unsigned char

b2)

void encoders_init(unsigned char a1, unsigned char a2, unsigned char b1, unsigned char b2)

Initializes the wheel encoders. The four arguments are the four pins that the wheel encoders are connected to,

according to the Arduino numbering: Arduino digital pins 0 – 7 correpsond to port D pins PD0 – PD7,

respectively. Arduino digital pins 8 – 13 correspond to port B pins PB0 – PB5. Arduino analog inputs 0 – 5 are

referred to as digital pins 14 – 19 (these are the enumerations you should use for this library) and correspond to

port C pins PC0 – PC5. The arguments are named a1, a2, etc. with the intention that when motor A is spinning

forward, pin a1 will change before pin a2. However, it is difficult to get them all correct on the first try, and you

might have to experiment.

static int getCountsA()

static int getCountsB()

int encoders_get_counts_a()

int encoders_get_counts_b()

Returns the number of counts measured on A or B. For the Pololu wheel encoders, the resolution is about 3mm/

count, so this allows a maximum distance of 32767 × 3mm or about 100m. For longer distances, you will need to

occasionally reset the counts using the functions below.

static int getCountsAndResetA()

static int getCountsAndResetB()

int encoders_get_counts_and_reset_a()

int encoders_get_counts_and_reset_b()

Returns the number of counts measured on A or B, and resets the stored value to zero.

static unsigned char checkErrorA()

static unsigned char checkErrorB()

unsigned char encoders_check_error_a()

unsigned char encoders_check_error_b()

These functions check whether there has been an error on A or B; that is, if both a1/a2 or b1/b2 changed

simultaneously. They return 1 if there was an error, then reset the error flag.

13. Wheel Encoders Page 35 of 35