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<A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A>
<UL>
<LI><A NAME="tex2html2790"
HREF="node136.html#SECTION005617100000000000000">4.6.17.1 Standard I/O Streams</A>
<LI><A NAME="tex2html2791"
HREF="node136.html#SECTION005617200000000000000">4.6.17.2 Printing functions</A>
<LI><A NAME="tex2html2792"
HREF="node136.html#SECTION005617300000000000000">4.6.17.3 Signals</A>
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<HR>
<H2><A NAME="SECTION005617000000000000000">
4.6.17 PIC16 C Libraries</A>
</H2>
<P>
<H3><A NAME="SECTION005617100000000000000">
4.6.17.1 Standard I/O Streams</A>
</H3>
<P>
In the <I>stdio.h</I> the type FILE is defined as:
<P>
<DL COMPACT>
<DT>
<DD>typedef char * FILE;
</DD>
</DL>This type is the stream type implemented I/O in the PIC18F devices.
Also the standard input and output streams are declared in stdio.h:
<P>
<DL COMPACT>
<DT>
<DD>extern FILE * stdin;
<P>
extern FILE * stdout;
</DD>
</DL>The FILE type is actually a generic pointer which defines one more
type of generic pointers, the <I>stream</I> pointer. This new type
has the format:
<P>
<DIV ALIGN="CENTER">
<TABLE CELLPADDING=3 BORDER="1">
<TR><TD ALIGN="CENTER">pointer type</TD>
<TD ALIGN="CENTER"><7:6></TD>
<TD ALIGN="CENTER"><5></TD>
<TD ALIGN="CENTER"><4></TD>
<TD ALIGN="CENTER"><3:0></TD>
<TD ALIGN="CENTER">rest of the pointer</TD>
<TD ALIGN="LEFT">descrption</TD>
</TR>
<TR><TD ALIGN="CENTER">stream</TD>
<TD ALIGN="CENTER">00</TD>
<TD ALIGN="CENTER">1</TD>
<TD ALIGN="CENTER">0</TD>
<TD ALIGN="CENTER">nnnn</TD>
<TD ALIGN="CENTER"><TT><I><I>uuuuuuuu uuuuuuuu</I></I></TT></TD>
<TD ALIGN="LEFT">upper byte high nubble is 0x2n, the rest are zeroes</TD>
</TR>
</TABLE>
</DIV>
<P>
<DIV ALIGN="CENTER">
</DIV>
<P>
Currently implemented there are 3 types of streams defined:
<P>
<DIV ALIGN="CENTER">
<TABLE CELLPADDING=3 BORDER="1">
<TR><TD ALIGN="CENTER">stream type</TD>
<TD ALIGN="CENTER">value</TD>
<TD ALIGN="CENTER">module</TD>
<TD ALIGN="CENTER">description</TD>
</TR>
<TR><TD ALIGN="CENTER">STREAM_USART</TD>
<TD ALIGN="CENTER"><TT>0x200000UL</TT></TD>
<TD ALIGN="CENTER">USART</TD>
<TD ALIGN="CENTER">Writes/Reads characters via the USART peripheral</TD>
</TR>
<TR><TD ALIGN="CENTER">STREAM_MSSP</TD>
<TD ALIGN="CENTER"><TT>0x210000UL</TT></TD>
<TD ALIGN="CENTER">MSSP</TD>
<TD ALIGN="CENTER">Writes/Reads characters via the MSSP peripheral</TD>
</TR>
<TR><TD ALIGN="CENTER">STREAM_USER</TD>
<TD ALIGN="CENTER"><TT>0x2f0000UL</TT></TD>
<TD ALIGN="CENTER">(none)</TD>
<TD ALIGN="CENTER">Writes/Reads characters via used defined functions</TD>
</TR>
</TABLE>
</DIV>
<P>
<DIV ALIGN="CENTER">
</DIV>
<P>
The stream identifiers are declared as macros in the stdio.h
header.
<P>
In the libc library there exist the functions that are used
to write to each of the above streams. These are
<DL>
<DT><STRONG>__stream_usart_putchar</STRONG></DT>
<DD>writes a character at the USART
stream
</DD>
<DT><STRONG>__stream_mssp_putchar</STRONG></DT>
<DD>writes a character at the MSSP stream
</DD>
<DT><STRONG>putchar</STRONG></DT>
<DD>dummy function. This writes a character to a user specified
manner.
</DD>
</DL>
In order to increase performance <I>putchar</I> is declared in stdio.h
as having its parameter in WREG (it has the wparam keyword). In stdio.h
exists the macro PUTCHAR(arg) that defines the putchar function in
a user-friendly way. <I>arg</I> is the name of the variable that holds
the character to print. An example follows:
<P>
<DL COMPACT>
<DT>
<DD>#include <pic18fregs.h>
<BR>#include <stdio.h>
<BR>
<BR>
PUTCHAR( c )
<P>
{
<P>
PORTA = c; /* dump character c to PORTA */
<P>
}
<BR>
<BR>
void main(void)
<P>
{
<P>
stdout = STREAM_USER; /* this is not necessary, since stdout points
<P>
* by default to STREAM_USER */
<P>
printf (''This is a printf test\n'');
<P>
}
<P>
</DD>
</DL>
<P>
<H3><A NAME="SECTION005617200000000000000">
4.6.17.2 Printing functions</A>
</H3>
<P>
PIC16 contains an implementation of the printf-family<A NAME="3404"></A>
of functions. There exist the following functions:
<P>
<DL COMPACT>
<DT>
<DD>extern unsigned int sprintf(char *buf, char *fmt, ...);
<P>
extern unsigned int vsprintf(char *buf, char *fmt, va_list ap);
<P>
extern unsigned int printf(char *fmt, ...);
<P>
extern unsigned int vprintf(char *fmt, va_lista ap);
<P>
extern unsigned int fprintf(FILE *fp, char *fmt, ...);
<P>
extern unsigned int vfprintf(FILE *fp, char *fmt, va_list ap);
</DD>
</DL>For sprintf and vsprintf <I>buf</I> should normally be a data pointer
where the resulting string will be placed. No range checking is done
so the user should allocate the necessary buffer. For fprintf and
vfprintf <I>fp</I> should be a stream pointer (i.e. stdout, STREAM_MSSP,
etc...).
<P>
<H3><A NAME="SECTION005617300000000000000">
4.6.17.3 Signals</A>
</H3>
<P>
The PIC18F family of microcontrollers supports a number of interrupt
sources. A list of these interrupts is shown in the following table:
<P>
<DIV ALIGN="CENTER">
<TABLE CELLPADDING=3 BORDER="1">
<TR><TD ALIGN="LEFT">signal name</TD>
<TD ALIGN="CENTER">description</TD>
<TD ALIGN="LEFT">signal name</TD>
<TD ALIGN="CENTER">description</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_RB</TD>
<TD ALIGN="CENTER" COLSPAN=1>PORTB change interrupt</TD>
<TD ALIGN="LEFT">SIG_EE</TD>
<TD ALIGN="CENTER">EEPROM/FLASH write complete interrupt</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_INT0</TD>
<TD ALIGN="CENTER">INT0 external interrupt</TD>
<TD ALIGN="LEFT">SIG_BCOL</TD>
<TD ALIGN="CENTER">Bus collision interrupt</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_INT1</TD>
<TD ALIGN="CENTER">INT1 external interrupt</TD>
<TD ALIGN="LEFT">SIG_LVD</TD>
<TD ALIGN="CENTER">Low voltage detect interrupt</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_INT2</TD>
<TD ALIGN="CENTER">INT2 external interrupt</TD>
<TD ALIGN="LEFT">SIG_PSP</TD>
<TD ALIGN="CENTER">Parallel slave port interrupt</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_CCP1</TD>
<TD ALIGN="CENTER">CCP1 module interrupt</TD>
<TD ALIGN="LEFT">SIG_AD</TD>
<TD ALIGN="CENTER">AD convertion complete interrupt</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_CCP2</TD>
<TD ALIGN="CENTER">CCP2 module interrupt</TD>
<TD ALIGN="LEFT">SIG_RC</TD>
<TD ALIGN="CENTER">USART receive interrupt</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_TMR0</TD>
<TD ALIGN="CENTER">TMR0 overflow interrupt</TD>
<TD ALIGN="LEFT">SIG_TX</TD>
<TD ALIGN="CENTER">USART transmit interrupt</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_TMR1</TD>
<TD ALIGN="CENTER">TMR1 overflow interrupt</TD>
<TD ALIGN="LEFT">SIG_MSSP</TD>
<TD ALIGN="CENTER">SSP receive/transmit interrupt</TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_TMR2</TD>
<TD ALIGN="CENTER">TMR2 matches PR2 interrupt</TD>
<TD ALIGN="LEFT"> </TD>
<TD ALIGN="CENTER"> </TD>
</TR>
<TR><TD ALIGN="LEFT">SIG_TMR3</TD>
<TD ALIGN="CENTER">TMR3 overflow interrupt</TD>
<TD ALIGN="LEFT"> </TD>
<TD ALIGN="CENTER"> </TD>
</TR>
</TABLE>
</DIV>
<P>
<DIV ALIGN="CENTER">
</DIV>
<P>
The prototypes for these names are defined in the header
file <I>signal.h</I>.
<P>
In order to simplify signal handling, a number of macros
is provided:
<UL>
<LI>[DEF_INTHIGH(name)] begin the definition of the interrupt dispatch
table for high priority interrupts. <I>name</I> is the function name
to use.
</LI>
<LI>[DEF_INTLOW(name)] begin the definition of the interrupt dispatch
table fo low priority interrupt. <I>name</I> is the function name
to use.
</LI>
<LI>[DEF_HANDLER(sig,handler)] define a handler for signal <I>sig.</I>
</LI>
<LI>[END_DEF] end the declaration of the dispatch table.
</LI>
</UL>Additionally there are two more macros to simplify the declaration
of the signal handler:
<UL>
<LI>[SIGHANDLER(handler)] this declares the function prototype for
the <I>handler</I> function.
</LI>
<LI>[SIGHANDLERNAKED(handler)] same as SIGHANDLER() but declares a
naked function.
</LI>
</UL>An example of using the macros above is shown below:
<P>
<DL COMPACT>
<DT>
<DD>#include <pic18fregs.h>
<P>
#include <signal.h>
<BR>
<BR>
DEF_INTHIGH(high_int)
<P>
DEF_HANDLER(SIG_TMR0, _tmr0_handler)
<P>
DEF_HANDLER(SIG_BCOL, _bcol_handler)
<P>
END_DEF
<BR>
<BR>
SIGHANDLER(_tmr0_handler)
<P>
{
<P>
/* action to be taken when timer 0 overflows */
<P>
}
<BR>
<BR>
SIGHANDLERNAKED(_bcol_handler)
<P>
{
<P>
__asm
<P>
/* action to be taken when bus collision occurs */
<P>
retfie
<P>
__endasm;
<P>
}
</DD>
</DL><B>NOTES:</B> Special care should be taken when using the above
scheme:
<UL>
<LI>do not place a colon (;) at the end of the DEF_* and END_DEF macros.
</LI>
<LI>when declaring SIGHANDLERNAKED handler never forget to use <I>retfie</I>
for proper returning.
</LI>
</UL>
<P>
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