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The PIC16F877A datasheet is at <a href="http://ww1.microchip.com/downloads/en/DeviceDoc/39582b.pdf" rel="ugc">http://ww1.microchip.com/downloads/en/DeviceDoc/39582b.pdf</a><br />
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See figure 2-3, which is the register file map for the 16F877A. &nbsp;TRISA and TRISD correspond to 85h and 88h, respectively.<br />
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Table 2-1 explains a little about TRISA, and redirects you to pages 43 and 150.<br />
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Section 4.1, &quot;PORTA and the TRISA Register&quot; hopefully explains what you need to know about TRISA, and there is a similar section for TRISD at sectoin 4.4, &quot;PORTD and the TRISD Register&quot;.
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I have recently been given code which was written to program a PIC16F877A. &nbsp;This code has been written in C.<br />
<br />
I understand the different ports but I dont understand what TRISA is and what they are used for.<br />
<br />
Also I have noticed in the code when each of the ports is setup the code is used:<br />
<br />
TRISA = 0xFF &nbsp; &nbsp;// sets to inputs<br />
PORTA = 0x00 // sets to zero<br />
<br />
TRISD = 0x4E // set bits (0,1,2,5) inputs, others outputs<br />
PORTD = 0x00<br />
<br />
What I dont understand is how does 0xFF sets this to an input, and also how does 0x4E set this to bit 0,1,2,5 as inputs and others outputs<br />
<br />
I have tried searching the internet but I dont really understand so if anyone would have a simple way of explaining this would be greatly appreciated
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I have recently been given code which was written to program a PIC16F877A.  This code has been written in C.

I understand the different ports but I dont understand what TRISA is and what they are used for.

Also I have noticed in the code when each of the ports is setup the code is used:

TRISA = 0xFF    // sets to inputs
PORTA = 0x00 // sets to zero

TRISD = 0x4E // set bits (0,1,2,5) inputs, others outputs
PORTD = 0x00

What I dont understand is how does 0xFF sets this to an input, and also how does 0x4E set this to bit 0,1,2,5 as inputs and others outputs

I have tried searching the internet but I dont really understand so if anyone would have a simple way of explaining this would be greatly appreciated

Setting up ports for PIC16F877A

C is a general-purpose, imperative computer programming language, supporting structured programming, lexical variable scope and recursion, while a static type system prevents many unintended operations. By design, C provides constructs that map efficiently to typical machine instructions, so it has found lasting use in applications that had formerly been coded in assembly language, including operating systems as well as various application software for computers ranging from supercomputers to embedded systems. It is distinct from C++ (which has its roots in C) and C#, and many later languages have borrowed directly or indirectly from C.