Problem with LCD using 8051 controller

[binojkumar]

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.

 

[mandar_mahajan]

8051 reset

There must be problem in ur hardware.

 

[mfarooq1]

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.

 

[sau_sol]

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

 

[srikanthsamaga]

8051 reset pin

As above suggestions I think your circuit doesn't have power on reset i.e. a cap and resistor combination at reset pin..

 

[binojkumar]

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.

 

[mandar_mahajan]

como fazer reset 8051 com capacitor

try this!!!!
& tell wether its working or not.

 

[bobsanjose]

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**

 

[binojkumar]

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.

 

[sau_sol]

how to reset 8051

which specific controller in 8051 family you are using

and if possible post your schematic

 

[davidgrm]

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