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kd7ost

RS232 and PIC's

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This is a question for the engineers. I'm thinking of MrRC-cam mostly.

Devices like the PDC-10 use a chip, like the MAX 232 in order to convert the RS232 signal from the GPS to TTL levels for the PIC. Is this always necessary? Are there ways of conditioning or buffering the RS232 signal with more discreet components and doing so reliably avoiding the MAX 232? Or is it best to simply use the converter chip?

Thanks in advance

Dan

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If all you want to do is receive the RS232 and input into the PIC, then do NOT use a MAX232. Instead, use a simple transistor buffer. You will avoid the cost and EMI/RFI issues of the MAX232.

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Can you direct me to any application notes or data on the usage? I would need to know what transistor to use and how to set it up to include any coupling or decoupling components.

Thanks for the fast response btw.

Dan

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The transistor can be nearly anything, such as a 2N2222A or 2N3904. The resistors are 1/8W. None of the components are critical.

The circuit is for Rx-only apps. If you need the PIC to send and receive RS-232 then the MAX232 will allow good compatibility with RS-232 devices.

post-6-1137986991_thumb.jpg

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