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Raspberry Pi Hardware Reference by Warren W. Gay

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CHAPTER 9

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UART

The Raspberry Pi has a UART interface to allow it to perform serial data communications. The data lines used are 3.3 V logic-level signals and should not be connected to TTL logic (+5 V) (they also are not RS-232 compatible). To communicate with equipment using RS-232, you will need a converter module.

RS-232 Converter

While an industrious person could build their own RS-232 converter, there is little need to do so when cheap converters are available.

Figure 9-1 shows a MAX232CSE chip interface that I use. (This unit supports only the RX and TX lines.) When searching for a unit, be sure that you get one that works with 3 V logic ...

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