[Moved] why max232 with 16f877a and RF 433MHZ ASK module

[sunnystar]

my project block diag:

keypad(input)=>pic16f877a=>max232=>DTMF encoder=>RF 433 ASK Tx => RF 433 ASK Rx=>DTMF decoder=>max232=>pic16f877a=>relays

the data is being correctly transmitted and received using max232.

so in cross questioning if i asked why i'm using max232 is then what will be the answer?? plz help me

 

[zeyad.kassaby]

max 232 is mainly to convert voltage level from ttl to -9vdc / +9vdc and also curren amp to prevent damage for pic ic used
hope it helps
ziad