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I have RPI A+ and with its single USB port, I am not able to install any software at the moment. (I have an USB hub on order)

I am trying to test new hardware I designed and want to see the output of the hardware Serial port. Is there some kind of command to see the serial out without the need to install Minicom or putty?

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Assuming you want to see what is arriving at the Pi's serial port.

The Pi's primary UART is connected to pins 8 (TXD, gpio 14) and 10 (RXD, gpio 15).

The grounds of the two machines needs to be connected as well as TX<--->RX and RX<--->TX.

All the Pi's gpios are 3V3. If you feed a 3V3 TTL (i.e. 0V or 3V3) to gpio 15 you can see what is being received with the following pi commands.

stty -F /dev/ttyAMA0 9600 # or the baud rate you are using
cat /dev/ttyAMA0

Press ctrl-c to stop. If the data you are sending is not text try the following instead

cat /dev/ttyAMA0 | od -x

The UART is normally used for boot messages and as a login console.

You could log in to the Pi via the serial link and a terminal emulator running on a PC.

In that case the PC's baud rate needs to be set to 115200 8N1.

Perhaps try that first.

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