Communicating to other uC at a distance of 100m or more

[emavil]

Hi guys, I am working with two microcontroller projects that communicates using SPI wherein both of them are 100meters apart. Is there any least possible electronic solution to this?

 

[tvthang]

Hi, to communicate between 2 uC, you should use UART, you use 2 MAX485 to exchange from TTL to RS485, in which distance may be 2km.

 

[sohailkhanonline]

Above solution is working. I have implemented it

 

[randell_xtian]

i suggest that you may used a RF IC/RF module for wireless communication.

 

[FvM]

If - for any reason - a SPI interface has to be extended to 100 m, then this can be done using multiple differential pairs and RS422 respectively RS485 driver/receiver. You should consider, however, the roundtrip cable delay of about 1 us.

 

[Sayem Ahmed]

One quetion freinds

when i am using a mcu with usart like 16f877 and only want to send data then should i have to use max233 or any of them for distant transmition.

Thanks.

 

[emavil]

thanks to all who responded. I am not familiar with RS485, currently i'm using buffer ICs like 74LS244 at the transmitter module and another 74LS244 at the receiver module. I am transmitting digital singals at TTL levels for SPI (Strobe, Data, Clock) using ordinary telephone cord. One line of the telephone cord is used to connect Grounds of the both modules. It worked. I also tried using UTP cable(Unshielded Twisted Pair) and it worked also for about 15 meters.

I would like to ask for technical support regarding the method that i'm using. What will happen to this configuration if i go for 50m or more?

Will my configuration affected with this "Ground Loop"?

 

[FvM]

Industrial RS485 networks are mostly using opto-isolated RS485 to achieve reliable operation also if ground voltage differences are present. It depends on your electrical enviroment, if RS85 is operational without isolation, probably yes. But you should activate potential interference sources for test, e. g. switch fluorescent lamps or electrical machines.

 

[b.zahedi]

max485 is very simple, for reliable communication you'd better use one in the transmitter side and another in the receiver side

 

[FvM]

I agrre with b.zahedi. I didn't read from your post (or couldn't believe) that you wanted to continue using single-ended TTL signals for distant communication, but I fear, he understood it correct.