CC2541 connect to optical encoder

The optical encoder outputs logic levels so this can absolutely be connected to the CC2541. You would of course need to create an encoder driver in SW.

Cheers,
Fredrik

Thank you for the reply, but what does SW means and how do I create an encoder driver in SW?

I want to code the CC2541, but below, I have the code for the PIC16F628A. Can anyone verify this code and help me to port and adapt these codes into CC2541.

/******************************************************************************
DC_motor_xtal.c - run a DC motor at xtal "clockwork" locked speed
Started 8 Apr 2013 - Copyright www.RomanBlack.com, allowed for public use,
you must mention me as the author and please provide
a link to my web page where this system is described;
www.RomanBlack.com/onesec/DCmotor_xtal.htm

PIC16F628A - 20MHz HS xtal (see web page for schematic)
Compiler - MikroC for PIC v8
PIC pins;
RA0 = digital ST input, quad encoder A
RA1 = digital ST input, quad encoder B
RB3 = CCP1 output, PWM to motor, HI = ON
RB0 = echo encoder A output
RB1 = echo encoder A output

PIC configs; MCRLE off, BODEN off, BORES off, WDT off, LVP off, PWRT on
******************************************************************************/

// This constant sets the motor speed. The value is in nanoSeconds per pulse,
// as we are using a quadrature encoder there are 4 pulses per encoder slot.
// My encoder had 36 slots, so that makes 36*4 or 144 pulses per revolution.
// Example; 1 motor rev per second = 144 pulses /sec.
// nS per pulse = 1 billion / 144 = 6944444
//#define MOTOR_PULSE_PERIOD 1736111 // 4 RPS
//#define MOTOR_PULSE_PERIOD 3472222 // 2 RPS
#define MOTOR_PULSE_PERIOD 6944444 // 1 RPS
//#define MOTOR_PULSE_PERIOD 13888889 // 0.5 RPS

// This constant sets the proportional gain. Basically it sets how much
// more PWM % is added for each pulse behind that the motor gets.
// ie; if set to 10, the PWM is increased by 10% for each pulse behind.
// Values must be within 1-50. Values of 10 or 16 worked well with
// low motor RPMs, for higher RPMs a smaller value like 2 to 8 can be used.
#define MOTOR_PROP_GAIN 10

// global vars
unsigned char rpos; // reference position of xtal based freq
unsigned char mpos; // actual motor position
unsigned char mlag; // amount the motor lags the reference
unsigned char enc_new; // holds motor's quadrature encoder data for testing
unsigned char enc_last;
unsigned long bres; // bresenham accumulator used to make ref frequency
unsigned char pins; // temporary var for echoing encoder signals

//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
void interrupt()
{
//-------------------------------------------------------
// This is TMR0 int, prescaled at 2:1 so we get here every 512 instructions.
// This int does the entire closed loop speed control;
// 1. updates encoder to see if motor has moved, records it position
// 2. updates reference freq generator, records its position
// 3. compares the two, sets PWM if motor lags behind reference
// 4. limit both counts, so they never roll, but still retain all error
//-------------------------------------------------------
// clear int flag straight away to give max safe time
INTCON.T0IF = 0;

// 1. updates encoder to see if motor has moved, records it position
enc_new = (PORTA & 0b00000011); // get the 2 encoder bits
if(enc_new != enc_last)
{
if(enc_new.F1 != enc_last.F0) mpos++; // record new motor position
else mpos--;
enc_last = enc_new;
}

// 2. updates reference freq generator, records its position
bres += 102400; // add nS per interrupt period (512 insts * 200nS)
if(bres >= MOTOR_PULSE_PERIOD) // if reached a new reference step
{
bres -= MOTOR_PULSE_PERIOD;
rpos++; // record new xtal-locked reference position
}

// 3. compares the two, set PWM% if motor lags behind reference
if(mpos < rpos) // if motor lagging behind
{
mlag = (rpos - mpos); // find how far it's lagging behind
if(mlag >= (100/MOTOR_PROP_GAIN)) CCPR1L = 100; // full power if is too far behind
else CCPR1L = (mlag * MOTOR_PROP_GAIN); // else adjust PWM if slightly behind
}
else // else if motor is fast, cut all power!
{
CCPR1L = 0;
}

// 4. limit both counts, so they never roll, but still retain all error
if(rpos>250 || mpos>250)
{
rpos -= 50;
mpos -= 50;
}

}
//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

//=============================================================================
// MAIN
//=============================================================================
void main()
{
//-------------------------------------------------------
// setup PIC 16F628A
CMCON = 0b00000111; // comparators OFF, all pins digital

PORTA = 0b00000000; //
TRISA = 0b00000011; // RA0,RA1 used for digital ST encoder inputs

PORTB = 0b00000000; //
TRISB = 0b00000000; // RB3 is CCP1 PWM out, RB0,RB1 are encoder echo outputs

// set TMR2 to roll every 100 ticks, PWM freq = 5mil/16/100 = 3125 Hz
T2CON = 0b00000111; // TMR2 ON, 16:1 prescale
PR2 = (100-1); // PWM total period of 100

// set PWM out on CCP1
CCPR1L = 0; // PWM range 0-100% = start with PWM of 0%
CCP1CON = 0b00001100; // CCP1 on, set to PWM mode

// TMR0 used for interrupt, makes interrupt every 512 insts
OPTION_REG = 0b10000000; // PORTB pullups OFF, TMR0 on, 2:1 prescale

//-------------------------------------------------------
// setup before main loop
Delay_mS(200); // allow PSU voltages time to stabilise

// setup vars etc, will be used in interrupt
bres = 0;
rpos = 0;
mpos = 0;

// finally start TMR0 roll interrupt
INTCON = 0b10100000; // GIE=on, TMR0IE=on

//-------------------------------------------------------
// main run loop
while(1)
{
//-------------------------------------------------
// We don't need to do anything in main loop as the motor speed
// control is done entirely in the TMR0 interrupt.

//-------------------------------------------------
// For convenience in setting up the encoder trimpots,
// echo the two encoder pins out two spare PORTB digital outputs!
pins = 0;
if(PORTA.F0) pins.F0 = 1;
if(PORTA.F1) pins.F1 = 1;
PORTB = pins; // output those two pins only (PWM output is not affected)
}
}
//-----------------------------------------------------------------------------

Thank you

Hello,

I have attached the reference design of a  CC2541 to the encoder.  Can anyone check this and correct me if it is wrong.