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epicnote
Joined: 11 Oct 2009
Posts: 3
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| Incremental rotary encoder interface |
 Posted: Sun Oct 11, 2009 11:49 pm |
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Hello guys, I am a newbie here. By the way, I have finished programming the encoder, relays and keypad. I attached the encoder Channel A to RB0 and Channel B to RB1 of pic16f877a. Then I only used key number 1, 2 and 3 of keypad module where the 3 columns connected to RB2, RB3 and RB4 while the row1 connected to RB5. For the relay, a SPST relay connected to RD7 and a DPDT relay connected to RD6. So this is my C program using CCS C compiler for the system. Hope you guys can help me in guiding the program to complete.
| Code: |
#include <16F877A.H>
#fuses HS, PUT, NOWDT, NOPROTECT, NOBROWNOUT
#use delay (clock=20000000) //MCU clock 20MHz
#use rs232 (UART1, baud=9600)
void main()
{
signed int encoder; //Encoder counter
int current_pos; //current_pos indicates the position
port_B_pullups(TRUE); //Port B pull up
set_tris_D(0x00); //Port D set as output
set_tris_B(0xC7); //Port B pin RB2 to RB4 as output and others as input
while(TRUE)
{
output_low(PIN_B2); //Clear RB2
if(!input(PIN_B5)) //If keypad 1 is pressed
{
output_high(PIN_B2);
delay_ms(25);
if(current_pos==0) //Check initial position
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
}
else if(current_pos==5) //Check initial position
{
output_high(PIN_D7); //Motor moves down(CCW)
output_low(PIN_D7);
if(!input(PIN_B0)&&!input(PIN_B1)) //Check if B0 and B1 is equal to 0
{
encoder--;
if(encoder==0)
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
current_pos=encoder; //Store last position
}
}
}
else if(current_pos==10) //Check initial position
{
output_high(PIN_D7); //Motor moves down(CCW)
output_low(PIN_D6);
if(!input(PIN_B0)&&!input(PIN_B1)) //Check if B0 and B1 equal to 0
{
encoder--;
if(encoder==0)
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
current_pos=encoder; //Store last position
}
}
}
}
output_low(PIN_B3); //Clear RB3
if(!input(PIN_B5)) //If keypad 2 is pressed
{
output_high(PIN_B3);
delay_ms(25);
if(current_pos==0) //Check initial position
{
output_high(PIN_D7); //Motor moves up(CW)
output_high(PIN_D6);
if(!input(pin_B0)&&!input(PIN_B1)) //Check if B0 and B1 equal to 0
{
encoder++;
if(encoder==5)
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
current_pos=encoder; //Store last position
}
}
}
if(current_pos==5) //Check initial position
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
}
if(current_pos==10) //Check initial position
{
output_high(PIN_D7); //Motor moves down(CCW)
output_low(PIN_D6);
if(!input(PIN_B0)&&!input(PIN_B1)) //Check if B0 and B1 equal to 0
{
encoder--;
if(encoder==5)
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
current_pos=encoder; //Store last position
}
}
}
}
output_low(PIN_B4); //Clear RB4
if(!input(PIN_B5)) //If keypad 3 is pressed
{
output_high(PIN_B4);
delay_ms(25);
if(current_pos==0) //Check initial position
{
output_high(PIN_D7); //Motor moves up(CW)
output_high(PIN_D6);
if(!input(PIN_B0)&&!input(PIN_B1)) //Check if B0 and B1 equal to 0
{
encoder++;
if(encoder==10)
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
current_pos=encoder; //Store last position
}
}
}
if(current_pos==5) //Chech last position
{
output_high(PIN_D7); //Motor moves up(CW)
output_high(PIN_D6);
if(!input(PIN_B0)&&!input(PIN_B1)) //Check if B0 and B1 equal to 0
{
encoder++;
if(encoder==10)
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
current_pos=encoder; //Store last position
}
}
}
if(current_pos==10) //Check initial position
{
output_low(PIN_D7); //Motor stops
output_low(PIN_D6);
}
}
}
}
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Hence, my question is:
1) Is that relevant to create a program with so many IF statement?
2) Then is the code above can complete my task? |
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Steve H
Guest
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| Posted: Mon Oct 12, 2009 10:31 am |
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You did not say if the code works or not - I will assume that it did. Your program is not so big that the multiple if statements are a real problem with readability.
You are building a state machine - you can search Google for "State machine C", here is a reasonable link I found. State machines are a simple way to code this kind of problem.
http://tactilicio.us/2008/02/12/some-code-snippets-for-a-simple-c-state-machine/
HTH - Steve H. |
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epicnote
Joined: 11 Oct 2009
Posts: 3
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| Posted: Sat Oct 17, 2009 10:41 am |
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Guys, I have created a new program that using external source for timer0, become counter of channel B of the encoder. The program runs when I push key 1 of the keypad. Then the motor will move clockwise for 2 revolutions and stop. Once I run the program, the motor stops when finished 2 revolution. Then when I want to start again with pushing the key 1, the relays contact without stopping. So why does it happen?? Anybody can help me?? Here is my coding:
| Code: |
#include <16F877A.H>
#fuses HS, PUT, NOWDT, NOPROTECT, NOBROWNOUT
#use delay (clock=20000000) // MCU clock 20MHz
#use rs232 (UART1, baud=9600)
void setup_encoder(); //Read encoder
void scankeypad(); //Read keypad
unsigned int8 time;
void main()
{
set_tris_D(0x00); //port D set as output
set_tris_B(0xFF); //port B input
set_tris_A(0b11111111); //RA4 as input
while(TRUE)
{
setup_encoder();
scankeypad();
}
}
void setup_encoder()
{
setup_counters(RTCC_EXT_H_TO_L,RTCC_DIV_1);
set_rtcc(0);
}
void scankeypad()
{
while(TRUE)
{
output_low(pin_D5);
if(!input(pin_B2)) //If keypad1 is pressed
{
output_high(pin_D7); //Motor moves clockwise
output_high(pin_D6);
delay_ms(50);
time=get_rtcc();
}
if(time>=96)
{
output_low(pin_D7); //Motor stops
output_low(pin_D6);
set_rtcc(0);
}
}
}
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ferrousduke
Joined: 31 Mar 2008
Posts: 29
Location: Mumbai, India
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| Posted: Sat Oct 17, 2009 11:51 pm |
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| Do you have any schematics illusrating connections that you've made ? Explain abt the task too. |
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epicnote
Joined: 11 Oct 2009
Posts: 3
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| Posted: Sun Oct 18, 2009 1:55 am |
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Sorry for unclear details. So this is my circuit from isis. Thanks for the respond 
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