PIC16F877, sample coding regarding the use of switch

[lightgreen]

Homework Statement

I'm learning PIC recently. Below is the coding that i have prepared and the attachment is the connection that I used. My question is, why the 2 LEDs will on immediately once i trigger the PIC? This is because the result is not something that should be coming out. What's wrong with my connection or my coding?

Below is the coding part:
define osc 8
TRISA.0 = 1
TRISA.1 = 1
TRISD.0 = 0
TRISD.1 = 0

L1 var portd.0
L2 var portd.1
s1 var porta.0
s2 var porta.1

Main
portd = 0
if s1 = 0 then
L1 = 1
else
L1 = 0
endif
if s2 = 0 then
L2 = 1
else
L2 = 0
endif
pause 500
goto Main
end

Homework Equations

The Attempt at a Solution

 

[Valkarie]

I think the coding is correct, but there is something wrong with the connection. The LEDs will on immediately when i trigger the PIC because the initial value of the port A and port D are both 0. Therefore, if s1=0 and s2=0, L1 and L2 will be 1.

 

[Mene]

I would first suggest checking the connection to make sure it is correct and that there are no loose or faulty connections. It is also important to make sure that the PIC is properly programmed and that the code is error-free.

In terms of the coding, I would recommend using more descriptive variable names to make it easier to understand the purpose of each variable. Additionally, it is important to initialize all variables before using them in the code.

One potential issue that I see is that the LEDs are being turned on immediately because the initial state of the switches may be high (1) instead of low (0). This can be fixed by using pull-down resistors to ensure that the initial state of the switches is low.

Another thing to check is the logic of the code. Are the LEDs supposed to turn on when the switches are pressed (logic 0) or when they are released (logic 1)? Make sure the logic is consistent throughout the code.

I would also recommend adding comments to the code to explain what each section is doing, which can help with troubleshooting and understanding the code in the future. Additionally, testing the code step by step and using debugging tools can help identify any errors or issues.

Overall, it is important to carefully check the connection and code to ensure everything is correct and functioning as intended. If there are still issues, it may be helpful to consult with a more experienced programmer or refer to the PIC's datasheet for more information.