I am making a SCR(Thyristor) trigger by using 8051 microcontroller. I have a here is a zero cross detecting (ZCD) circuit which detects the zero points and this is conveyed to the 8051 which will do further action.
The ZCD circuit is made up of BJT transistor(s) and gives a pulse of 5 V . So is it necessary to add an ADC in between the ZCD and 8051?
PS:I am trying to first simulate in multisim, and its not working (I have directly connected the output of ZCD to pin p1.0 of 8051).
edit(updated problem):sorry for not clarifying the problem.I mistakenly used led word for probe thinking both are same. You can see one round thing connected to pin P2.0(bottom right). It is the probe. What I was trying to do is to detect the pulse from ZCD and convey it to 8051. 8051 will take the input and turn on the probe, and then again go for checking it. SCR(with optocoupler) will come in place of probe, but thats second part. I am just trying to make the first part work correctly.The probe blinks at first -90 to 0 while it should only blink when the pulse is given to p1.0 port.
$MOD51 ; This includes 8051 definitions for the Metalink assembler ORG 0000H; loop:MOV P2,#00H;//make probe off SETB P1.0;//make the p1.0 as input port AGAIN:JNB P1.0,AGAIN;//loop here until p1.0 is high MOV P2,#0FFH;//turn on the probe sjmp loop;//go for checking the pulse again-infinite loop END;