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rfjhh
Joined: 31 Mar 2011
Posts: 51
Location: Mexico
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| Communication LabView-PIC |
 Posted: Fri Mar 22, 2019 12:30 pm |
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I'm trying to communicate between a 16f887 and LabView, but I can not read strings. My code is as follows:
| Code: |
#include <16F887.h>
#device adc=10
#fuses INTRC_IO,NOWDT,NOPROTECT,PUT,NOLVP,NOBROWNOUT
#use delay(clock=8M)
#use rs232(baud=9600,xmit=PIN_A2,rcv=PIN_A3)
#include<LCD420.c>
#include<input.c>
#use fast_io(A)
#use fast_io(B)
void configura()
{
set_tris_a(0xff);
set_tris_b(0xf0);
setup_adc(sAN0);
lcd_init();
setup_oscillator(osc_8MHz);
setup_adc(ADC_CLOCK_INTERNAL);
SETUP_ADC_PORTS(sAN0);
set_adc_channel(0);
}
void main()
{
char mensaje[12];
configura();
for(;;)
{
char mensaje[31];
lcd_gotoxy(1,1);
printf(lcd_putc,"Pba get_string");
output_bit(PIN_B0,0);
if(kbhit())
{
output_bit(PIN_B0,1);
get_string(mensaje,30);
delay_ms(5);
output_bit(PIN_B0,0);
lcd_gotoxy(1,2);
printf(lcd_putc,"%30s", mensaje);
}
}
}
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I do not know how to insert the code image in labview. |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Fri Mar 22, 2019 2:25 pm |
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quick general comments
1) you need to add 'ERRORS' as an option in #USE RS232(.....ERRORS)
this will keep the HW UART from overflowing and 'locking up'.
edit.. OOPS ! you're NOT using the hardware UART. You actually should. Now you're using a software or 'bitbang' UART, so there could be a timing problem....
get_string() will wait forever for 30 characters or a CR ( carriage return)..
Now I'm assuming you've got a USB<>TTL module between PC and PIC. Cut LABVIEW code to be a 'terminal' and have the KBD send to USB<>TTL module, loopback TXD to RXD, and see KBD data on the PC SCREEN. This will confirm you ARE sending data to the PIC.
I don't know how well it works with a SW UART though others will.
2) The ADC clock is wrong, you should not use 'internal '. Check with the datasheet, adc section, there's a chart of proper ADC clocks vs PIC clock speed.
Jay |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19539
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| Posted: Fri Mar 22, 2019 2:34 pm |
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ADC_CLOCK_INTERNAL is not recommended for your clock. At 8MHz you
need ADC_CLOCK_DIV_32
Honestly, use the hardware UART, pins C6, and C7. Software serial
should only be used as a 'last resort'.
You talk about communicating with LabView. Describe your hardware to
make this connection. Have you got RS232 transceivers? |
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dluu13
Joined: 28 Sep 2018
Posts: 395
Location: Toronto, ON
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| Posted: Fri Mar 22, 2019 3:18 pm |
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I do not like SW uarts one bit unless you are only transmitting. According to the manual, if you are using SW uart, then you must poll kbhit() at least 10 times the rate of your baud rate. Otherwise you risk missing incoming uart data.
When I used SW uart, I even had ADC reading in the main loop screw up my SW uart. |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Fri Mar 22, 2019 6:17 pm |
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gads I feel OLD now.. I used to MAKE HW UARTs from a handfull of 7400 series chips all wirewrapped. Used a 4702 timebase chip for the clock. Sad thing is I SAW one of them the other day in a bin, along with a 6402 which was one of the first CMOS UARTS on the market.
I've used SW UARTs for years, run at 600 baud, no problems. One trick is 'interleaving' the tasks within the 'bit' widths. Mice were done that way, using 16C71s(?), I do recall the Microchip application note. probably on their website though I prefer hardcopy books to thumb through.
Jay |
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rfjhh
Joined: 31 Mar 2011
Posts: 51
Location: Mexico
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| SW vs HW |
| Posted: Mon Mar 25, 2019 8:58 am |
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Jay
Yes I'm using an USB<>TTL module between PC and PIC. I think you're ok, I don't know if LabView inserts a CR by default in each string sent, I'll check it. By the way, I'm using pins C6, and C7.
May you explain me the difference between SW and HW please.
Regards |
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dluu13
Joined: 28 Sep 2018
Posts: 395
Location: Toronto, ON
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| Posted: Mon Mar 25, 2019 9:09 am |
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| If you don't know if labview inserts a CR, then you can run labview's output to your TTL USB module and check it on a terminal program like realterm. That will show you the characters |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19539
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| Posted: Mon Mar 25, 2019 9:12 am |
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Software and hardware.
Most PIC's have a hardware UART, on specific pins.
CCS can use this hardware or provide a UART 'emulation' in code. A
'software' UART.
Your post at the start was using pins A2 & A3, which are not the
UART hardware pins for this chip.
Using a software UART, there is no buffering at all. The code must be sitting
'polling' the kbhit function at least 10* per bit, and start reception
immediately. Any pause and data will be missed/lost.
Transmitting with the software UART, providing you are not using anything
interrupt driven, can be quite reliable. Reception though is much more
likely to have issues.
Use hardware if you can. |
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dluu13
Joined: 28 Sep 2018
Posts: 395
Location: Toronto, ON
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| Posted: Mon Mar 25, 2019 11:00 am |
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Regarding transmitting using a software UART:
If allowed, you can use something like
| Code: | disable_interrupts(INTR_GLOBAL);
printf("...");
enable_interrupts(INTR_GLOBAL); |
Just be careful that you can afford to miss an interrupt of whatever you will be disabling. |
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rfjhh
Joined: 31 Mar 2011
Posts: 51
Location: Mexico
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| Fixed |
| Posted: Mon Mar 25, 2019 12:37 pm |
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Thanks all of you guys.
Just a CR concatenated to the string and get_string() is working. |
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