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can anybody tell what are the steps to occur serial intrpt?

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nikhileshsawarkar

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hi friends,

can anybody tell what are the steps to occur serial receive
interrupt?:?:


regards,
Gaurav.
 

Re: can anybody tell what are the steps to occur serial intr

first you have to consider and setup the serial sfr and then serial ISR. interrupt will be genearted well one byte starting bit to stop bit is recieved including every bit even parity if used.

Added after 4 minutes:

ISR Rountine

Code: 
.org 0023h
	ljmp serialint

serialint:
	jbc ti, transmitted
	jbc ri, received	
	reti
transmitted:
                                           ;your code after a byte is transmitted
	reti
received:
	mov recbuff,sbuf
                                         ;your code after a byte is recieved
                reti


for initializing serial sfr
serialinit:
	anl pcon ,#7fh
	anl tmod,#0fh
	orl tmod, #20h
	mov th1, #baudnum
	setb tr1		;timer 1 running as baud generator
	mov scon, #40h
	setb ren		;enable serial reception
	ret
 

Re: can anybody tell what are the steps to occur serial intr

Hi nikhileshsawarkar

Is your question about a specific device/hardware or a general question?

regards ... Polymath
 

Re: can anybody tell what are the steps to occur serial intr

hi,

i am getting data from computer at a baud rate of 28.8 Kbps, and receiving in
microcontroller (8052). i have set a baud rate 28.8 Kbps in microcontroller also
to receive. but i am missing some samples in communication.

i think controller take some time in going to serial (or any ) ISR. and for receiving data in SBUF we should make RI bit reset(0) in serial ISR. meanwhile data is continously coming to the controller and in the process we are missing samples.

what should be the procedure?

regards,
Gaurav.
 

Re: can anybody tell what are the steps to occur serial intr

A good idea is to implement a buffer ..
How to do this is desribed in this article:

Overview
These routines provide a interrupt driven serial input and output, which is intended to replace CIN and COUT in the Serial I/O Routines. This code uses separate transmit and receive buffers in Internal RAM, so that no external chips are required.
Click to expand...

https://www.pjrc.com/tech/8051/uartintr.html

You can use the whole upper 128 bytes of the 8052 internal RAM as the receiving buffer .. and this should fix the problem with missing characters ..

Regards,
IanP
 

Re: can anybody tell what are the steps to occur serial intr

Hi nikhileshsawarkar
It sounds like you may have a receive buffer overflow problem - do you do any software check for this?
Have you implemented any form of handshake? Hardware or software flow-control.
This will halt the transmitter until the receiver is ready for the next data word.

From my reading of my MCS51 data the SIO hardware has no receive buffer overflow flag - you can loose data without this being flagged (unlike a PIC). You will need to guard aginst this in your design.

regards ... Polymath
 

Re: can anybody tell what are the steps to occur serial intr

In 8051/2 there is no serial buffer ..
The question is: has he created a buffer?

Regards,
IanP
 

Re: can anybody tell what are the steps to occur serial intr

IanP said:
In 8051/2 there is no serial buffer ..
The question is: has he created a buffer?

Regards,
IanP
Click to expand...

As I finished using 87C552 in 1992, I have to refer to the data book. According to the Philips Data PCF83C552, there is an INPUT SHIFT REG. and an S0BUF on the SIO and the data book states:
The serial port is also receive buffered
Click to expand...

You may not think that a single byte buffer constitues a buffer, however it does. The SIO would be hard pressed to work without it.

I presume you are talking about a software implemented multi-byte buffer.

Even if a multi-byte buffer is implemented, it cannot guarantee to prevent data loss - it may make it worse because of the software overhead to service it - depending on the other system tasks involved.

If the data stream is so long as to require a multi-byte buffer, I would recommend some form of handshake - that is why it was created.

best regards ... Polymath
 

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