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TL
Joined: 15 Sep 2003
Posts: 75
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| How to flush software UART Rx buffer? |
 Posted: Fri Jul 18, 2008 7:21 am |
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Hi, I know how to flush a hardware UART Rx buffer but how do you flush a software one? Can someone check whether the following code is correct? Also, is it a good idea to use the FORCE_SW option in the "#use RS232" line for a software UART (see code below)? Thanks.
| Code: |
#include <18F6720.h>
#use fast_io(a)
#use fast_io(b)
#use fast_io(c)
#use fast_io(d)
#use fast_io(e)
// #use fast_io(f)
#use fast_io(g)
#byte port_a = 0xF80
#byte port_b = 0xF81
#byte port_c = 0xF82
#byte port_d = 0xF83
#byte port_e = 0xF84
#byte port_f = 0xF85
#byte port_g = 0xF86
// See CCS help file to see definitions
#FUSES NOWDT // No Watch Dog Timer
//#FUSES WDT // Watch Dog Timer
//#FUSES WDT128 //Watch Dog Timer uses 1:128 Postscale
#FUSES XT //Crystal osc <= 4mhz
#FUSES PUT //Power Up Timer
#FUSES PROTECT //Code protected from reading
#FUSES NOOSCSEN //Oscillator switching is disabled, main oscillator is source
#FUSES BROWNOUT //Reset when brownout detected
#FUSES BORV42 //Brownout reset at 4.2V
#FUSES STVREN //Stack full/underflow will cause reset
#FUSES NOCPD //No EE protection
#FUSES NOLVP //Low Voltage Programming on B3(PIC16) or B5(PIC18)
#FUSES NOWRT //Program memory not write protected
#FUSES NOCPB //No Boot Block code protection
#FUSES NOEBTRB //Boot block not protected from table reads
#FUSES NOEBTR //Memory not protected from table reads
#FUSES NOWRTD //Data EEPROM not write protected
#FUSES NOWRTC //configuration not registers write protected
#FUSES NOWRTB //Boot block not write protected
// 4MHz clock
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS, STREAM=COMMS)
#use rs232(baud=9600, xmit=PIN_G1, rcv=PIN_G2, ERRORS, STREAM=VTS)
#use rs232(baud=9600, parity=N, xmit=PIN_G3, bits=8, STREAM=PRINTER)
#use rs232(baud=9600, xmit=PIN_E5, rcv=PIN_E4, ERRORS, STREAM=EXT, FORCE_SW)
char in_packet[50];
void getReplyFromExt (void)
{
U8 i=0;
char ch;
// Flush any spurious characters waiting
while(kbhit(EXT)) fgetc(EXT);
// Wait for reply from External
while( !kbhit(EXT) );
// If char in RX buffer...
if(kbhit(EXT)) // If data in Rx buffer
{
do
{
ch=fgetc(EXT);
in_packet[i++]=ch;
} while(ch != 0x0D);
}
}
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Ttelmah
Guest
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| Posted: Fri Jul 18, 2008 7:32 am |
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A software UART, has _no_ buffering at all, in either direction.
Best Wishes |
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TL
Joined: 15 Sep 2003
Posts: 75
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| Posted: Fri Jul 18, 2008 7:44 am |
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Thanks. Does it mean that the following 2 lines can be deleted from the function? Also, I assume FORCE_SW option is correct in the "#use RS232" line.
| Code: |
// Flush any spurious characters waiting
while(kbhit(EXT)) fgetc(EXT);
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