Hi..
Hi I am using PIC 18F25J10 whose VDD is 3.3 V and a PIC 16F877A whose VDD is 5.0V. I need to have the RS232
communication between this two devices. But they can't be connected directly, because of their voltage levels are
different.(If i connect --> according to the data sheets RS232 will not work and ports of 3.3 device may burn or reduce its life time).
so can any one please suggest me a way to connect this two devices.
If the both PICs are in close proximity, on the same PCB, you want to use asynchronous serial communications, not RS-232. In which case a level shifter/translator would do the job.
You could either use discrete components or an IC to perform this task:
**broken link removed**
TI, MAXIM, NXP and other manufactures make specific ICs for the job.