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need help to write code for 8051

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Moderators: Ajay, Junied , abbas1707, Arun Kumar V, pdi33, Shailesh NAYAK, ۞ TPS ۞, shyam, sashijoseph

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ExperimenterUK

Mon Nov 17 2008, 11:25AM

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ExperimenterUK wrote ...

sks wrote ...

Hello Mr Arun,
i hv checked the code modified by you. either i don't understand the code or may be sum bugs are there. i hv rewrite the blinker again using timer flag, please check and comment.
thanks all
sks

@sks
In your " Tue Nov 11 2008, 04:21AM" post, did you intend to use an interrupt to
service the timer overflow ?

@sks
I asked about the interrupt because in the code you posted there are references to
an interrupt routine. (;timer0 isr and reti)
Arun assumed you were using an interrupt routine and was trying to make it work.
That is why Arun's post did not make sense to you.

Learning all the time

This post has been thanked 1 time

sks

sks

Tue Nov 18 2008, 01:58AM

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Hello Mr ExperimenterUK,
thanks fr the post. In your " Tue Nov 11 2008, 04:21AM" post, did you intend to use an interrupt to service the timer overflow ?" the answer is NO i was trying to write the code using Timer to blink a LED, that is it. as u know i hv never used timer before, that's a mistake. pl check the posted code on "Wed Nov 12 2008, 10:34PM" and comment, i know Mr Arun is busy fr a week or so.
thanks all
sks

sks

Wed Nov 19 2008, 12:00AM

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Joined: Thu Jul 31 2008, 07:51AM

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Hi all,
i hv written a code to communicate between PC and 8051 using Hyper Terminal. i m facing some problem like (1) i don't see my data string which is inside 8051 in Terminal window. (2) if i type A in my PC Keyboard i am getting a data in 8051 Port1 using 8 LEDs, but i couldn't recognize what type of data is that. is it in ASCII, HEX or what? please help me by clarifying.
thanks all
sks

CODE:

;8051 Serial communication using Hyper Terminal

;Received Data from PC is to be Displayed in Port_1

;Send data from 8051 is to be displayed in HyperTerminal

;Baud rate is 4800

        ORG     0000H

        MOV     P2,#0FFH        ;Make p2 as input port

        MOV     TMOD,#20H       ;Timer1 in Mode2 Auto Reload

        MOV     TH1,#0FAH       ;Baud rate is 4800

        MOV     SCON,#50H       ;8_Bit Data,1_Stop Bit

        SETB    TR1             ;Start Timer1

        MOV     DPTR,#MESSAGE    ;Load Pointer for Message

MAIN_1:

        CLR     A               ;Clera Accumulator

        MOVC    A,@A+DPTR       ;Load Data in Accumulator

        JZ      MAIN_2          ;Jump to Main_2 if data is zero

        CALL    SEND            ;Send data to PC

        INC     DPTR

        SJMP    MAIN_1

MAIN_2:

        MOV     A,P2            ;Load input data from Port2 in Accu

        CALL    SEND            ;Send data to PC

        CALL    RECV

        MOV     P1,A            ;Load Accu Data in P1

        SJMP    MAIN_2

SEND:

        MOV     SBUF,A

WAIT:

        JNB     TI,WAIT         ;Wait till data send is completed

        CLR     TI

        RET

RECV:

        JNB     RI,RECV

        MOV     A,SBUF

        CLR     RI

        RET

MESSAGE:

Db 'COMMUNICATIN TERMINAL IS READY'

        END

[ Edited Wed Nov 19 2008, 10:03AM ]

pdi33

Wed Nov 19 2008, 05:32AM

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Joined: Mon Jun 04 2007, 09:28AM

Posts: 773
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hi sks,
ur doubt is quite valid. All communication from/to the PC uses ASCII system for communication. So the data u received from the PC is ASCII and u have to convert it to decimal first for processing. As for the sending is concerned, the data u defined is already in ASCII so it should logically be seen on the hyperterminal, so there seem to be some error in communication.possible reasons could be:
1.u have not set the hyperterminal setting to 4800 baud
2. what is the crystal frequency u have chosen in ur hardware? 12mHz. or 11.059Mhz.
3. check if uhave connected the Rx of 8051 to Tx of PC and vice versa through the MAX232.

Also add 00 at the end of ur message for proper termination as according to ur logic, the loop continues sending the message string until it encounters 0.

DB ' your message',0

[ Edited Wed Nov 19 2008, 05:36AM ]

* inspired to develop,developing to inspire *

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sks

sks

Wed Nov 19 2008, 07:45AM

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Joined: Thu Jul 31 2008, 07:51AM

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Hello pdi,
thank u very much for clearing my doubt. my hyper terminal baud rate setting is 4800. i m using 11.0592mhz crystal in my kit and one thing i hv to check the cable for TX to RX and RX to TX part and let u know tomorrow. also i will correct the code as advised by u. one more thing i will like to know for ASCII to DEC Conversion is 30 common factor?.
thanks again
sks

pdi33

Wed Nov 19 2008, 07:07PM

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as long as the value is numerical (0 to 9), then adding 30h is sufficient. Note that while outputting a byte of data, first u have to split it into two nibbles, convert them in ascii and then output them to the PC.

* inspired to develop,developing to inspire *

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sks

sks

Thu Nov 20 2008, 12:46AM

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Joined: Thu Jul 31 2008, 07:51AM

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Hello pdi,
Thanks for the reply. i have doubts regarding Hyper Terminal & ASCII Codes. i am using NSK 8051 kit having MAX232 built in, and using a complete PARALLEL cable, the same cable is used in my ISP. The cable is working alright in ISP. Also i have done a schematic in Proteus like in my kit. when i simulate using same code in Proteus the 8 LEDs in Port1 shows different values not like in my kit. here is the fresh code, it's for just to receive data from PC. Also i m attaching the schematic. some of the showing values in my kit are also here fr ur study. please help me by clarifying my doubts. i am sorry for a lengthy post.
thanks all
sks
;Receive Byte of Data Serially From PC & put them
;in Port1 of 8051
;Baud 4800,8_bit,1stop_bit

ORG 0000H
MOV TMOD,#20H ;Timer1 in Mode2 (AutoReload)
MOV TH1,#0FAH ;Baud rate 4800
MOV SCON,#50H ;8_Bit,1_Stop_Bit,REN Enabled
SETB TR1 ;Start Timer1
HERE:
JNB RI,HERE ;Stay here till a byte is received
MOV A,SBUF ;Load received byte in Accu
MOV P1,A ;Load data in Port1
CLR RI ;Get ready for next Byte
SJMP HERE
END
The showing Values in my Kit are like
0=06,1=67,2=33,3=66,4=19,5=65,6=32,7=64,8=0C,A=5F,B=2F,C=5E,D=17,a=4f,b=27,c=4e so on

pdi33

Thu Nov 20 2008, 04:09AM

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Posts: 773
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hi sks,
ur code seems fine and should work. I have simulated ur code in the proteus ckt u have posted and it works just as fine.So i think there seems to be some conflict in the hyperterminal setting.
Try using this terminal software ( very good one!!) and check again. be sure to set baud rate,8N1 and flow control to 'none'. As ur kit is using the sae UART pins for entering ISP mode, there might be some conflict in thecontrol lines used in the serial port ( DTR/CTS). So be sure to keep the flow control to none.
http://www.8051projects.net/downloads112.html

[ Edited Thu Nov 20 2008, 04:12AM ]

* inspired to develop,developing to inspire *

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sks

sks

Thu Nov 20 2008, 04:40AM

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Hi pdi,
thanks. i think the settings what u hav suggested is already there. 8N1 u mean
8_bit, parity NONE, 1 stop_bit i think. it is there. my ISP is another DEVICE. i am not using my NSK kit for flashing/programming, it just for testing codes and running programs. Any way i will check everything thoroughly and let u know tomorrow. one thing pl let me know in Proteus the values are showing like 0=01110000,1=01110001,A=10000001,B=10000010,a=11100001 and so on. what it means? pl give me a clue.
thanks
sks

pdi33

Thu Nov 20 2008, 06:43AM

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yep,
i too got the same readings initially and they are wrong. The mistake i did in the simulation was keeping the crystal frequency to 12Mhz. Note that proteus does not take on the crystal frequency connected to XTAL . It works just fine even when u do not connect the crystal in te circuit at all just like the RST and EA/Vpp pins. The main frequency used for the simulation should be set in the properties window of the uC which is by default 12Mhz. So if u change that to 11.0592Mhz, u will get the true ASCII output on the LEDs(verified).
0 -> 0011 0000 -> ASCII 30h
1 -> 0011 0001 -> ASCII 31h
A -> 0100 0001 -> ASCII 41h
... and so on.
do take care of the flow control.
good luck.