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zhiling0229
Joined: 13 Sep 2006
Posts: 10
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| Non-ascii data stream via RS232 communication problem? |
 Posted: Tue Oct 03, 2006 11:41 pm |
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Hi,
I'm new in serial communication. I wanted to write a serial test code before I intend to write my program. Here is the test code that I'm writting and I need some pointers. Thanks.
| Code: |
#include <16F877A.h>
#fuses XT,NOWDT,NOPROTECT
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_A3, rcv=PIN_A2) // use pin A2 as receiver and pin A3 as transmitter
void main()
{
//Do I need to disable the ADC to enable serial transmission?
printf("What do I put here?");
// Is there anything else I need just to generate 1 line of data stream?
} |
I need to generate a stream of data "0D180174002001" which is all in hexadecimal. If I'm not mistake the command printf will generate the ASCII code to be transmitted to the RS232 port. How can I generate the data stream above. Thanks
Last edited by zhiling0229 on Fri Oct 06, 2006 4:26 am; edited 1 time in total |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Oct 03, 2006 11:53 pm |
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The putc() or fputc() functions will send a single byte of raw data.
Example:
| Code: |
#include <16F877.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
void main()
{
int8 i;
int8 data[7] = {0x0D, 0x18, 0x01, 0x74, 0x00, 0x20, 0x01};
for(i = 0; i < sizeof(data); i++)
putc(data[i]);
while(1);
} |
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asmallri
Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia
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| Posted: Tue Oct 03, 2006 11:53 pm |
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| Code: |
char mystring[] = {0x0D, 0x18, 0x01, 0x74, 0x00, 0x20, 0x01};
//.....
for (i = 0; i<7, i++)
putc(mystring[i]);
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_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!
Last edited by asmallri on Wed Oct 04, 2006 1:48 am; edited 1 time in total |
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asmallri
Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia
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| Posted: Tue Oct 03, 2006 11:55 pm |
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One day, possibly sometime in the distant future, I am going to beat PCM Programmer to the posting by a few seconds instead of always the other way around....
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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zhiling0229
Joined: 13 Sep 2006
Posts: 10
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| Posted: Wed Oct 04, 2006 1:07 am |
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Thanks guys,
Was wondering. PCM Programmer use Port C Pin 6 and 7. If I want to use Port A pin 2 and pin 3 is this the soruce code?
| Code: | #include <16F877>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_A2, rcv=PIN_A3, ERRORS)
void main()
{
int8 i;
int8 data[7] = {0x0D, 0x18, 0x01, 0x74, 0x00, 0x20, 0x01};
for(i = 0; i < sizeof(data); i++)
putc(data[i]);
while(1);
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Oct 04, 2006 1:25 am |
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ERRORS doesn't work with a software UART. The compiler ignores it.
You can remove it. |
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zhiling0229
Joined: 13 Sep 2006
Posts: 10
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| Posted: Wed Oct 04, 2006 1:50 am |
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| Thanks PCM programmer and asmallri you both have been a great help. |
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rnielsen
Joined: 23 Sep 2003
Posts: 852
Location: Utah
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| Posted: Wed Oct 04, 2006 6:26 am |
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One thing to remember, if you are going to use a Software UART and intend on receiving data through the port you will need to poll your receive pin to determine if you have a character coming in. The hardware interrupt only works if you use the hardware pin associated with it.
Ronald |
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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| Posted: Wed Oct 04, 2006 11:29 am |
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| Quote: | ERRORS doesn't work with a software UART. The compiler ignores it.
You can remove it. |
PCM Programmer may be right but in the CCS example of using an RS232 multi-drop bus
You'll see the following
| Code: |
#bit ninth_bit = RS232_ERRORS.7
#bit collision = RS232_ERRORS.6
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Now errors leads to the posting of the variable RS232_ERRORS and the multi-drop BUS is on PIN B0 so it isn't a hardware UART port. You might conclude that ERRORS has some functionality w.r.t the software UART |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Oct 04, 2006 1:33 pm |
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What I meant was, only the hardware UART has the capability to get
an overrun error and lock up. If you use ERRORS with a hardware
UART, the compiler will insert code to detect and automatically clear
an overrun error, if one occurs. Since a soft UART can't lock-up,
the compiler ignores the ERRORS directive and won't generate the
special code that it does for the hardware UART.
I wasn't referring to the other aspects of the RS232_ERRORS variable
with respect to a soft UART. |
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zhiling0229
Joined: 13 Sep 2006
Posts: 10
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| Posted: Fri Oct 06, 2006 4:25 am |
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Hi guys,
I just tested the programme. I used a advanced serial data logger to acquire the data. The problem is while sending the data I monitor the data logger. After the 2 second delay. the data logger only able to acquire part of the transmission:
which is : 0x01, 0x74, 0x00, 0x20, 0x01 (the header 0x0D,0x18 did not register)
Any ideas guys?
The source code I used is as below:
| Code: | #include <16F877A.h>
#use delay(clock=4000000)
#fuses XT, NOBROWNOUT, NOLVP, NOWDT
#use rs232(baud=9600, xmit=PIN_A2, rcv=PIN_A3)
struct lcd_pin_def
{
BOOLEAN B0; // B0
BOOLEAN B1; // B1
BOOLEAN B2; // B2
BOOLEAN B3; // B3
BOOLEAN B4; // B4
BOOLEAN B5; // B5
BOOLEAN B6; // B6
BOOLEAN B7; // B7
};
struct lcd_pin_def LCD;
#byte LCD = 0x06 // portB address on 16F877A
#use fast_io(D)
void main() {
int8 i;
int8 data[7] = {0x0D, 0x18, 0x01, 0x74, 0x00, 0x20, 0x01};
set_tris_b(0x00); // graphic lcd control lines all output
LCD.B0 = 1;
delay_ms(2000);
LCD.B0 = 0;
for(i = 0; i < sizeof(data); i++)
putc(data[i]);
while(1);
} |
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Ttelmah
Guest
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| Posted: Fri Oct 06, 2006 6:20 am |
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Try the following (note how much nicer it looks with the 'code' button...).
| Code: |
void main() {
int8 i;
int8 data[7] = {0x0D, 0x18, 0x01, 0x74, 0x00, 0x20, 0x01};
set_tris_b(0x00); // graphic lcd control lines all output
LCD.B0 = 1;
output_high(PIN_A2);
delay_ms(2000);
LCD.B0 = 0;
for(i = 0; i < sizeof(data); i++)
putc(data[i]);
while(1);
}
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Until you carry out some I/O on the serial pins, they are 'idle', which on a booting PIC, means set as an input. The receiver can then miss the first falling edge of the first character. I would have expected a 'garbage' character in front of the stuff that is received.
Best Wishes |
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