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vidya • Feb 6, 2007

help for 89c51

hi all,
im doing a project with 89c51.i have wriiten ALP and it gets loaded into the chip's memory.but,no output is reflected.that is,the chip doesn't react for even asimple 'PORT' do i rectify this.Am i missing out any initializations...if so,wat are the initial setups to be done?
waiting for reply eagerly.pls help.
thanking you
maheshkrishnan • Mar 28, 2007
Hi Vidya,
Did you checked the Xtal connections given correctlly with correct value with ranges from "10 - 13 Mhz"
Then If you are using 8051 it having internal Rom so no need for using external memory, you should be making the "EA" pin number i hope it is 31 for the 8051 make it to HIGH or (VCC).
Then I am sure you will get the output with out any problem.
then comeback with good projects.

mahesh krishnan
RachaelP • Mar 28, 2007
Hi Vidya,

What port are you looking at when trying to get it to output? If you are trying to output on Port 0 then its a little bit odd in that '0' drives low but write '1' it is floating and/or high-Z input. So basically you need to add external pull-ups on Port 0 pins that are being used as outputs.

Hope this helps,

hemant • Mar 31, 2007
this is good solution i need another one if you able to get
i m interfacing gsm modem to my microcontroller.i need to send sms
through it.
i am using AT commands for that.the command to send sms (AT+ CMGS)
terminates with in my program i hav tried all ways to send ctrl-Z at end of
my sms.but it takes this as
a character or string only.also i tried with ascii value of ctrl-Z but
of no use.

i am able to see the transmitted commands on hyper-terminal through
serial interface & also on serail window while debugging.
the commands are as follows with 2ms delay between each of them.

AT ,, AT+CMGS = mobile no. , "message to be sent " ctrl-Z it is for the only end of statement

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