microcontroller to microcontroller communication

[avl]

dear sir/madam;

i had communicated Freescale MC9S08AW60 to PCsuccessfully  but in second application  unable to communicate with microcontroller PIC 18f452

In this application

Mc9s08AW60 is unable  to get data from microchip PIC 18f452 where as it is able to send data to PIC 18f452

Points already covered by me.

1.> Software is same which is communicating  from PC. ( hence all setting are same as well as all initialisation what we are using in PC communication )

2.> IC MAX232 ( In case of PC communication ) is removed and RX and TX are connected to each other.

3.> Transmission had gone through properly.

4.> unable to get data from microcontroller. 

I request a fast feedback .it will be highly appreciated.

BR
Hasan

[Lundin]

- Do you get any receive flags at all set in the S08? Such as framing error, overrun error etc? If not, they aren't connected properly. Measure on Rx pin with an oscilloscope. Or perhaps the debugger is destroying the "clear-by-reading" flag registers. Run the program without debugger connected.

- Any buffers etc between the MCUs? Are both MCUs running at the same voltage?

- Less likely: missing pull-up on RX line. PIC clock being too inacurrate, yielding a baudrate fault larger than 3%. In these cases you should at least get framing errors etc.

Btw is there any particular reason why you would use a MAX232 in new designs? Why not use an alternative without the huge caps, like MAX202?