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arunb
Joined: 08 Sep 2003 Posts: 492 Location: India
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Connecting several Rxd pins and Txd pins together ? |
Posted: Wed Apr 06, 2005 7:24 am |
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MCU: 16F628
Compiler: PCM
Hi,
I connected the Rxd pin and the TXd of two PIC 16F628s together. The junction I connected to a MAX 232 Ic ( the way it should be done). The PC's COM port is then connected to the MAX IC.
I find that I am unable to communicate with either of the PICs. when both of them are connected together, but each of them worked well when alone. I checked supply voltages they were OK.
I could post the code as well , but I would like to know if this kind of connection is OK ?. Or do I have to use I2C , SPI for this ?
thanks
arun |
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Mark
Joined: 07 Sep 2003 Posts: 2838 Location: Atlanta, GA
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Posted: Wed Apr 06, 2005 8:23 am |
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So you tied 2 outputs together! So how can one of them transmit a low when the other is high? To answer your question, No you just can't tie them together. Your best bet is to use RS485 and each chip will need its own transceiver. |
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Neutone
Joined: 08 Sep 2003 Posts: 839 Location: Houston
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Re: Connecting several Rxd pins and Txd pins together ? |
Posted: Thu Apr 07, 2005 8:40 am |
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arunb wrote: | MCU: 16F628
Compiler: PCM
Hi,
I connected the Rxd pin and the TXd of two PIC 16F628s together. The junction I connected to a MAX 232 Ic ( the way it should be done). The PC's COM port is then connected to the MAX IC.
I find that I am unable to communicate with either of the PICs. when both of them are connected together, but each of them worked well when alone. I checked supply voltages they were OK.
I could post the code as well , but I would like to know if this kind of connection is OK ?. Or do I have to use I2C , SPI for this ?
thanks
arun |
Try connecting both TxD to an AND gate then connect the output of the AND gate to the MAX232 chip. The two pic's can not talk at the same time but if only one replys at a time it should work fine. |
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