Problem with LCD using 8051 controller

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binojkumar

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Hi friends im developing a project using 8051 core , after turn on the the power suply
every time i should press the rest button to start running controller and LCD.

I found the problem, All peripherals are working , but lcd is not working , it will work only aftre reset. any suggestion for that? pls help me...
thnks in advance.
 

reset 8051

ur reset circuit is not working or not present. you must reset ur controller for at least 2 machine cycles. it can be made from 2 components a resistor and a capacitor. values depends on the clock frequency but us 10K and 10uf its very common.
 

how reset switch working in 8051

for removing this problem

place a capacitor of say 10uF between the reset pin and the supply

such that

+5V ---- (+ve of capacitor 10uF/16V -ve of capacitor) ---- reset pin
 

state the function of reset pin of 8051

I have connected all this circuits, capacitor and resistr, all the peripherals are working but LCD is not working..it requires rest. I have written the code with delay, not considering the buzy flag of LCD.
 

reset circuit of 8051

Hi,

are there any pins that need to go to a high state after reset? If so, the internal pullup after reset is VERY weak and often can not pull a pin high. You need toi use external pullpus in such a case or you switch the portpin to low and then to high, much stronger pullups are involved in this action.
Just a guess because I have seen problems like yours in the past connected to the weak pullup.

Bob
**broken link removed**
 

reset circuit in 8051

Hi, this is not the problem of pull up, if i connect LED in any port pin it will blink(blinking prgm) when i turn on the power. no need to reset.
 

how to reset 8051

which specific controller in 8051 family you are using

and if possible post your schematic
 

reset function in 8051

I have had these problems in the past and solved it by putting the LCD init code in a function and then calling the function 3 times at start up. Some makes of display seem to take a while at power up before they are ready to accept data/commands. I hope this helps
 

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