How to Read Data SSI Encoder

Projects Programming
1

const int CLOCK_PIN = 4; // Blue Pin
const int DATA_PIN = 3; // Green Pin
const int CS_PIN = 8; // Yellow Pin
const int BIT_COUNT = 24; // 24 Bit Mode

const int DATA_ENABLE_PIN = 2;
const int DE_PIN = 5;

void setup(){

pinMode(DATA_PIN, INPUT); pinMode(CLOCK_PIN, OUTPUT);
pinMode(CS_PIN, OUTPUT);
pinMode(DE_PIN, OUTPUT); pinMode(DE_PIN, LOW);
pinMode(DATA_ENABLE_PIN, OUTPUT); pinMode(DATA_ENABLE_PIN, LOW);
digitalWrite(CLOCK_PIN, HIGH); digitalWrite(CS_PIN, HIGH);

Serial.begin(115200);
}

void loop()
{
float reading = readPosition();
if (reading >= -0.5)
{
Serial.print("Reading: ");
Serial.println(reading, 2);
}
delay(1000);
}

//read the current angular position
float readPosition()
{
// Read the same position data twice to check for errors
unsigned long sample1 = shiftIn(DATA_PIN, CLOCK_PIN, CS_PIN, BIT_COUNT);
unsigned long sample2 = shiftIn(DATA_PIN, CLOCK_PIN, CS_PIN, BIT_COUNT);
delayMicroseconds(20); // Clock must be high for 20 microseconds before a new sample can be taken
if (sample1 != sample2) return -1.0;
return ((sample1 & 0x0FFF) * 360UL) / 4096.0;
}

//read in a byte of data from the digital input of the board.
unsigned long shiftIn(const int data_pin, const int clock_pin, const int cs_pin, const int bit_count)
{
unsigned long data = 0;

digitalWrite(cs_pin, LOW);
for (int i = 0; i < bit_count; i++)
{
data <<= 1;
digitalWrite(clock_pin, LOW);
delayMicroseconds(1);
digitalWrite(clock_pin, HIGH);
delayMicroseconds(1);

data |= digitalRead(data_pin);

}
digitalWrite(cs_pin, HIGH);
return data;
}

  • Reading: 359.91 (Serial monitor)
    Only the above values continue to appear. It doesn't work properly. What the reason?
2

Please post a datasheet in English.

The wiring diagram does not show how the encoder is powered.

3

@jremington

Thank you for answer.
Please send the datasheet in English.
EPM50_English.pdf (317.1 KB)

The power supply is applying 12V.

4

@jremington

No matter how much I think about it, I don't know what's wrong.

5

just a quick look, don't you mean

digitalWrite (DE_PIN, LOW);
6

this seems to be a better datasheet:
https://www.acotron.com/download/f1e043260331e4700b581b854bbaed5c_EPM502.pdf

and base of the info in it, I think you may have any issue with the voltage levels if you are using a MAX3491 (operates at 3.3V)

image

I would suggest you try to use a different RS485 driver. something like this one for example.

OR... have a go with this sample code from this thread on the same topic!

hope that helps....

7

I find it odd that the code is using Pin 8 but the schematic doesn't show it attached to anything.

8

Unfortunately, the OP never came back to say if they tried the code or if it worked. That code is probably completely untested.

9

@gcjr
@sherzaad
@johnwasser

Thank you very much for your reply.

Maybe a chip
Can I change 'MAX3491' to 'MAX491'?

Please review.

I will change the chip and test it with the example source code you provided.

10

might work....

11

@sherzaad
@gcjr
@johnwasser
@jremington

circuit
circuit1141Γ—507 145 KB

const int DATA_PIN = 2;
const int CLOCK_PIN = 3;
const int RE = 4;
const int DE = 5;
const int REESET = 6;
const int DIR = 7;

void setup()
{
//setup our pins
pinMode(DATA_PIN, INPUT);
pinMode(CLOCK_PIN, OUTPUT);
pinMode(RE, OUTPUT);
pinMode(DE, OUTPUT);
pinMode(REESET, OUTPUT);
pinMode(DIR, OUTPUT);

digitalWrite(RE, LOW);
digitalWrite(DE, LOW);
digitalWrite(REESET, HIGH);
digitalWrite(DIR, HIGH);

Serial.begin(115200);
}

unsigned long ReadEncoder()
{
unsigned long encoderData = 0;

digitalWrite(CLOCK_PIN, LOW);
digitalWrite(CLOCK_PIN, HIGH);
for (int i = 0; i < 24; i++)
{
encoderData <<= 1;
digitalWrite(CLOCK_PIN, LOW);
encoderData |= digitalRead(DATA_PIN);
digitalWrite(CLOCK_PIN, HIGH);
}
return encoderData;
}

void loop()
{
unsigned long enc = ReadEncoder();

if (enc & 0x00800000) // Bit 24 is the overflow bit
{
Serial.println("Overflow");
}
else
{
float revolutions = enc / 1024;
Serial.println(revolutions, 4); // Display to 4 decimal places
}
delay(500);
}

It doesn't work.
Is there any way..? help.

12

thank you sm

13

  1. datasheet url :
    https://forum.arduino.cc/uploads/short-url/qFE8N7U5WuOenCKzYlw6FUwCkXU.pdf
    https://forum.arduino.cc/uploads/short-url/lsrVDY2ydzYBz7SkXYI001v2Npz.pdf

  2. circuit image :

    a1
    a1781Γ—456 41.5 KB

    a2
    a21130Γ—507 51 KB

    a3

I ran tests with 3 different chips, but didn't get the desired results.
I tried 3 ways, but couldn't get the result.
Why? help me.

14

@sherzaad
@gcjr
@johnwasser
@jremington
@gnownee

This is a problem with the firmware source code.

  1. It is a delay problem of digitalWrite / digitalRead.
  2. To solve this problem, 'FAST' function was used.
  3. So, I solved it.

(1) Circuit
DATA+ 4
DATA- GND
CLOCK+ 7
CLOCK- GND

(2) Firmware

const int DATA_PIN = 4;
const int CLOCK_PIN = 7;
digitalPinFast pinTest(DATA_PIN);
digitalPinFast pinTest2(CLOCK_PIN);

unsigned long ReadEncoder(){
unsigned long encoderData = 0;
delay(1); digitalWrite(CLOCK_PIN, HIGH);
for (int i = 0; i < 14; i++)
{
if(i>0){encoderData <<= 1;}
pinTest2.digitalWriteFast(LOW);
delayMicroseconds(1);
pinTest2.digitalWriteFast(HIGH);
delayMicroseconds(1);
if(i>0){ encoderData |= bitRead(PIND, 4); }

}
return encoderData;
}

Thank you for leaving a reply.
Thank you for caring me. have a good day.