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I am trying to communicate UART with PIC32MX795F512L. I am really confused with this thing that we should use MAX232/ADM3202 or pins will directly commnicate. Because in some microcontroller, it is not required but in others it is required. Please help.

Thanks

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closed as unclear what you're asking by Leon Heller, PeterJ, Daniel Grillo, JIm Dearden, Matt Young Jul 23 '15 at 13:22

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    \$\begingroup\$ That fully depends what device you're communicating with. \$\endgroup\$ – Tom L. Jul 15 '15 at 7:57
  • \$\begingroup\$ You have not told us about the other device that is supposed to communicate with the PIC. Is it a computer with a built-in RS232 interface or some kind of USB virtual serial device? \$\endgroup\$ – Christoph Jul 15 '15 at 7:57
  • \$\begingroup\$ Also see this question: electronics.stackexchange.com/questions/44571/… \$\endgroup\$ – Christoph Jul 15 '15 at 7:58
  • \$\begingroup\$ @Christoph yes it will communicate with computer \$\endgroup\$ – anna carolina Jul 15 '15 at 8:15
  • \$\begingroup\$ If it has to communicate with PC,use of RS232 level shifter is must \$\endgroup\$ – Sanjeev Kumar Jul 15 '15 at 8:17
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Yes, you will need to have MAX232 or ADM3203 along with allied components for making your microcontroller communicate with a computer over UART/USART Serial interface.

RS232 is a standard and defines the signal level requirements at transmitter and receiver. Therefore to make it compatible with the TTL output, an interface (coverter) component is required which shall convert the TTL logic to RS232 standard and vice versa. MAX232 does that for you.

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  • \$\begingroup\$ Many motherboard rs232 can work with TTL logic levels these days. The signal may need to be inverted, but this can be done at the microcontroller level. A full tranceiver is often not required. \$\endgroup\$ – Scott Seidman Jul 15 '15 at 10:33
  • \$\begingroup\$ @ScottSeidman: Yes, true. But at the basic level, people will assert that you need one. \$\endgroup\$ – WedaPashi Oct 15 '15 at 12:10
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If you are using UART to communicate with another controller with same logic levels, you don't need max232 ic.

RS232 is a standard that also has specifications on logic levels.Your PC can understand only RS232 logic levels while your controller controller communicates in TTL logic. To bridge this, you need MAX232 ic.

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