VidorEncoder

Encoder

Hardware Required

Arduino MKR Vidor 4000
A quadrature encoder

Circuit

The encoder is connected as follows:

ENC_A to A0
ENC_B to A1

Pin name	Description	Pin number
AREF		0
A0	ENC0_A	1
A1	ENC0_B	2
A2	ENC1_A	3
A3	ENC1_B	4
A4	ENC2_A	5
A5	ENC2_B	6
A6	ENC3_A	7
D0	ENC3_B	8
D1	ENC4_A	9
D2	ENC4_B	10
D3	ENC5_A	11
D4	ENC5_B	12
D5	ENC6_A	13
D6	ENC6_B	14
D7	ENC7_A	15
D8	ENC7_B	16
D9	ENC8_A	17
D10	ENC8_B	18
D11	ENC9_A	19
D12	ENC9_B	20
D13	ENC10_A	21
D14	ENC10_B	22

Code

Include the VidorEncoder library, which is part of VidorPeripherals.
#include "VidorPeripherals.h"
#include "VidorEncoder.h"

You have a number of functions available to manage the encoder:

VidorEncoder(int index) - refer to pinout tab for pinout (index) in this page
void write(int32_t p); - resets the count value to "p"
int32_t read(); - returns the actual count

/*
This sketch shows how to use the Encoder IP in MKRVidor 4000
Quadrature encoders are a very common way to detect position (and speed) of a moving part, like a DC motor.
Normally, in the microcontroller world, decoding a quadrature encoder has serious limitations since all egdes must be counted, otherwise the final number will be wrong. This is usually accomplished using interrupts, but over a certain revolution speed the intinsic overhead of servicing an interrupt destroys the count reliability.

Using the FPGA to perform decoding allows:
- not to lose any edge until the revolution speed is less than some million RPM :)
- we can "read" the encoder at any time, because the FPGA is counting independently

Circuit:
connect ENC_A to A0 and ENC_B to A1
*/

#include "VidorGraphics.h"
#include "VidorEncoder.h"

// Initialize Encoder #0 (connected to A0 and A1)
// Refer to the online documentation to find which pins correspond to a given index
// This assignment may change between bitstreams
VidorEncoder encoder(0);

void setup() {
Serial.begin(9600);

// wait for the serial monitor to open,
// if you are powering the board from a USB charger remove the next line
while (!Serial);

// Let's start the FPGA
if (!FPGA.begin()) {
Serial.println("Initialization failed!");
while (1) {}
}
}

void loop() {

// Read the encoder
int value = encoder.read();
Serial.print("Encoder value: ");
Serial.println(value);

#if 1

// Wait one second with interrupts disabled
noInterrupts();
// We can't call delay() since it uses interrupts, so use busy loops
for (int i = 0; i < F_CPU / 10; i++) {
asm ("nop");
}
interrupts();

#else
delay(200);
#endif

if (value >= 200 || value <= -200) {
// Reset the count
encoder.write(0);
}
}

[Get Code]

Encoder

Hardware Required

Circuit

Code

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