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Sending PWM duty cycle over RF

 
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Gerhard



Joined: 30 Aug 2007
Posts: 144
Location: South Africa

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Sending PWM duty cycle over RF
PostPosted: Mon Oct 29, 2007 2:57 pm     Reply with quote
Hi. I am trying to read the value of a adc and sent it over rf to the reciever, to use that value as the duty cycle for the PWM of a motor. Problem is that it is not a smooth change in speed as i am turnig the pot. It looks as if the delay between the sent and recieve influence the value so much that it is visible on the motor speed. Can you please give some recomendation as to do it better.

Transmit
Code:
set_adc_channel(1);   
delay_us(200);
speed = read_adc();
if(speed>160)
{
output_low(pin_A5);
output_high(pin_A4);
set_pwm1_duty(speed-200);
setup_ccp1(CCP_PWM_H_H | CCP_PULSE_STEERING_C);
PutCC1000(PREAMBLE);
PutCC1000(0X0A);
PutCC1000(speed);
}


Recieve
Code:
set_adc_channel(0);
delay_us(20);
signal = read_adc();
if(signal<70)
{
if (CCRX_BUFFCOUNT >= 3) {   // As 3 bits ontvang is
temp = GetCC1000();
direction = GetCC1000();
speed = GetCC1000();            
if (temp == PREAMBLE) {   

if(direction==0x0A)
{                output_low(pin_A2);
                 output_low(pin_A4);
                 delay_ms(5);
                 set_pwm1_duty(speed-131);
                 setup_CCP1(CCP_PWM_H_H | CCP_PULSE_STEERING_C
                                        | CCP_PULSE_STEERING_B);
                 output_high(pin_A3);
                 output_high(pin_B4);
                 output_low(pin_A5);
                 output_low(pin_A1);
                 
}


On the recieve side the adc cahnnel 0 is only an RSSI to determine the signal strength.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Mon Oct 29, 2007 3:26 pm     Reply with quote
Quote:
if(speed>160)
{
output_low(pin_A5);
output_high(pin_A4);
set_pwm1_duty(speed-200);
setup_ccp1(CCP_PWM_H_H | CCP_PULSE_STEERING_C);
PutCC1000(PREAMBLE);
PutCC1000(0X0A);
PutCC1000(speed);
}

You execute the code if the speed is 161 or higher.
But then you subtract 200 from the speed before you give it to the
pwm duty cycle function. Then you are giving the function a value
of -39. I'm sure you don't intend to do that.
Gerhard



Joined: 30 Aug 2007
Posts: 144
Location: South Africa

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PostPosted: Mon Oct 29, 2007 8:31 pm     Reply with quote
Thanks, although it didn't solve the problem on the recieve side it helped on the transmit side LED.
Late night mistake.
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