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Mahdi
Joined: 21 Aug 2012
Posts: 47
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| full duplex uart problem |
 Posted: Mon Aug 26, 2013 8:52 am |
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hi.
I want to use usart serial interface for transmit and receive data between pic18f87j11 with 50mhz clock speed and dspic33fj256mc710 with 80mhz clock speed with probee ze10 rf module and 9600 baudrate, but I have a problem.
my connection is synchronous until when i use a delay in while().
how can i have a connection, without error and Synchronous with rx and tx pin?
Can i use RDA interrupt for receive data?
When i use getc() in while(1) and i use a delay, the connection lost and connection not synchronous.
Can i use a timer to putc and getc function?
Thanks
v4.130 |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Mon Aug 26, 2013 10:58 am |
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show your code.
and BTW are you using wireless ISM type transceivers ?? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19535
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| Posted: Mon Aug 26, 2013 12:37 pm |
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Basic thing.
EX_SISR.C
EX_STISR.C
You need to remember that the PIC only has a tiny amount of hardware buffering on the UART.
If you stop reading characters (or writing new ones to send), while you delay, communications will stop. Incoming data will be lost, and outgoing transmissions will stop.
The same is true on the PC (though most modern UART's have quite large buffers). Solution is interrupt driven comms (exactly what the PC does). |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Mon Aug 26, 2013 4:21 pm |
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to add to what Mr. T has said,
if there is a cheap ISM link in the picture, then
you will need to adopt some method of dc restoration and perhaps send 0x55 or 0xCC as filler chars to prevent character distortion in the received
data stream.
those pics of potential ISM cards are scary that way.
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RF_Developer
Joined: 07 Feb 2011
Posts: 839
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| Posted: Tue Aug 27, 2013 4:20 am |
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| asmboy wrote: | to add to what Mr. T has said,
if there is a cheap ISM link in the picture, |
Well, they appear to be Zigbee modules running off 3.3V. The PIC18F87J11 is also 3.3V capable so that's good. However its only capable of running up to 48MHz, so 50MHz is not good: may work sometimes, or with some chips, or when its cool, or... well, you shouldn't run them at 50MHz and expect them to work reliably.
As others have said, circular buffered, interrupt driven serial IO is without doubt the way to go. Its standard systems programming stuff, has been since the early sixties. To be honest had I been CCS I'd have built it into the compiler as a serial interface option long ago. |
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jeremiah
Joined: 20 Jul 2010
Posts: 1353
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| Posted: Tue Aug 27, 2013 4:42 am |
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| I'm glad they finally added it (buffered interrupt driven serial) to the compiler as well. |
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Mahdi
Joined: 21 Aug 2012
Posts: 47
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| Posted: Tue Aug 27, 2013 11:08 am |
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when i connect 2 18f pic series the uart work but when i connect dspic & 18f its not work and the connection not synchronous..
Please see the files below ....
receive code :
| Code: | #include <33fj32mc204.h>
#FUSES PR //Primary Oscillator
#FUSES NOIESO //Internal External Switch Over mode disabled
#FUSES EC //External clock with CLKOUT
#FUSES NOPUT //No Power Up Timer
#FUSES NOJTAG //JTAG disabled
#use delay(clock=40m) //high clock speed for this chip
#include <LCD.C>
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8,errors)
int test;
void main()
{
lcd_init();
while(true){
if (kbhit()){
test=getc();}
lcd_gotoxy(1,1);
printf(lcd_putc,"%u",test);
}
} |
transmit code:
| Code: | #include <18f87k22.h>
#FUSES NOWDT //No Watch Dog Timer
#FUSES NOXINST //Extended set extension and Indexed Addressing mode disabled (Legacy mode)
#FUSES ECH_IO //External clock ,high power
#FUSES NOPLLEN //4X HW PLL disabled, 4X PLL enabled in software
#FUSES NOFCMEN //Fail-safe clock monitor disabled
#FUSES NOIESO //Internal External Switch Over mode disabled
#use delay(clock=48m)
#use rs232(UART1,baud=9600,parity=N,bits=8,errors)
int test=12;
void main()
{
while(true){
putc(test);
}
} |
So it seems that the uart connection between 18f and dspic not synchronous and have problem
please download isis file and test it with above code
http://www.up2www.com/uploads/1377623243121.zip
thanks |
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asmallri
Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia
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| Posted: Tue Aug 27, 2013 12:09 pm |
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There is no need to download and test. If is obvious from you code you have used an UART receive interrupt handler and, as a consequence, it is no surprise that you have problems.
Use an interrupt driven receive ring buffer and your problem will go away.
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19535
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| Posted: Tue Aug 27, 2013 12:12 pm |
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Your problem is that you are not using the UART.....
The DsPIC's, have _relocatable_ peripherals. These have to be setup.
You need to use:
| Code: |
#pin_select U1TX=PIN_C6
#pin_select U1RX=PIN_C7
#use rs232(baud=9600,parity=N,UART1,bits=8,errors)
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Which tells the compiler to connect UART1, to pins C6, and C7, and then use this. Just using the pins in #use rs232, results in a software UART being implemented, so the data will be missed while you are writing to the LCD....
Best Wishes |
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Mahdi
Joined: 21 Aug 2012
Posts: 47
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| Posted: Tue Aug 27, 2013 1:24 pm |
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| Ttelmah wrote: | Your problem is that you are not using the UART.....
The DsPIC's, have _relocatable_ peripherals. These have to be setup.
You need to use:
| Code: |
#pin_select U1TX=PIN_C6
#pin_select U1RX=PIN_C7
#use rs232(baud=9600,parity=N,UART1,bits=8,errors)
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Which tells the compiler to connect UART1, to pins C6, and C7, and then use this. Just using the pins in #use rs232, results in a software UART being implemented, so the data will be missed while you are writing to the LCD....
Best Wishes |
thanks for your answer
but this my code
| Code: | #include <33fj32mc204.h>
#FUSES PR //Primary Oscillator
#FUSES NOIESO //Internal External Switch Over mode disabled
#FUSES EC //External clock with CLKOUT
#FUSES NOPUT //No Power Up Timer
#FUSES NOJTAG //JTAG disabled
#use delay(clock=40m) //high clock speed for this chip
#include <LCD.C>
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8,errors) |
i use uart and define the xmit and rcv pin in dspic chip.
this dspic chip (33fj32mc204) not have hardware uart that i can use it
i test your code but its not work
| Code: | #pin_select U1TX=PIN_C6
#pin_select U1RX=PIN_C7
#use rs232(baud=9600,parity=N,UART1,bits=8,errors) |
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jeremiah
Joined: 20 Jul 2010
Posts: 1353
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| Posted: Tue Aug 27, 2013 3:30 pm |
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| Mahdi wrote: |
this dspic chip (33fj32mc204) not have hardware uart that i can use it
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According to the chip data sheet, it has 1 hardware UART and it is located on peripheral pins (as noted above by another poster). |
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Mahdi
Joined: 21 Aug 2012
Posts: 47
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| Posted: Tue Aug 27, 2013 5:10 pm |
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| jeremiah wrote: | | Mahdi wrote: |
this dspic chip (33fj32mc204) not have hardware uart that i can use it
|
According to the chip data sheet, it has 1 hardware UART and it is located on peripheral pins (as noted above by another poster). |
when i use 4800 baud in receiver the data is clear and the connection is synchronous.
| Code: | #include <33fj32mc204.h>
#FUSES PR //Primary Oscillator
#FUSES NOIESO //Internal External Switch Over mode disabled
#FUSES EC //External clock with CLKOUT
#FUSES NOPUT //No Power Up Timer
#FUSES NOJTAG //JTAG disabled
#use delay(clock=40m)
#include <LCD.C>
#pin_select U1TX=PIN_C6
#pin_select U1RX=PIN_C7
#use rs232(baud=4800,parity=N,UART1,bits=8,errors) |
I do not know what to do anymore!! |
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temtronic
Joined: 01 Jul 2010
Posts: 9241
Location: Greensville,Ontario
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| Posted: Tue Aug 27, 2013 5:27 pm |
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As previously posted ....
"Use an interrupt driven receive ring buffer and your problem will go away." by Andrew
Have a look at the example 'ex_sisr.c' in the examples folder to see how to use a ring buffer
You _must_ use an ISR with buffer to get any reliable high speed serial data transfers .
I can get 115K200 using this method...so I know it works!
hth
jay |
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Mahdi
Joined: 21 Aug 2012
Posts: 47
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| Posted: Wed Aug 28, 2013 6:29 am |
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| temtronic wrote: | As previously posted ....
"Use an interrupt driven receive ring buffer and your problem will go away." by Andrew
Have a look at the example 'ex_sisr.c' in the examples folder to see how to use a ring buffer
You _must_ use an ISR with buffer to get any reliable high speed serial data transfers .
I can get 115K200 using this method...so I know it works!
hth
jay |
can you explain me about ring buffer and the ex_sisr.c and stisr.c well, i dont know about buffer on pic chip
thanks alot |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19535
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| Posted: Wed Aug 28, 2013 7:34 am |
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Seriously, nothing to do with the PIC....
This is basic standard programming.
Do a Google search on 'ring buffer'.
The whole point is that the PIC, only has a couple of characters of hardware buffering. It only takes a moment, to overflow these. It however (in common with just about every other chip), has the ability to tell you:
1) When a character has been received.
2) When a character can be sent.
These two events trigger 'interrupts', which can call code.
When '1' happens, you simply receive the character, and write it to the buffer. When you want to see if anything has been received, you look at the buffer, not the UART.
When you want to send data you write it to another buffer, and enable the interrupt on event '2'. The data is then sent automatically from the buffer to the UART as space becomes available in the hardware.
Just about _every_ piece of code on the market today, that sends/receives data from any computer, uses such buffers. The PC etc. etc..
Nothing to do with the PIC at all.
CCS gives examples of such a buffer for transmit, and for receive. Look at them.
With V5, there is also an option to generate such buffers automatically. |
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