The previous examples used the hardware UART. That means the compiler uses the internal UART registers and internal hardware (RxD(0) and TxD(0)) of the AVR. If you don’t have a hardware UART you can also use a software UART.

 

The Bascom compiler makes it easy to “create” additional UART’s. Bascom creates software UART’s on virtually every port pin.   

 

Remember that a software UART is not as robust as a hardware UART, thus you can get timing problems if you have lots of interrupts in your program.

 

For this example we use micro controller pins portc.1 and portc.2.

Connect portc.1 to TxD and portc.2 to RxD see the schematic above.

 

Change the $regfile and program this example:

 

$regfile = "m88def.dat"

$crystal = 8000000

$baud = 19200

 

Dim B As Byte

Waitms 100

 

'Open a TRANSMIT channel for output

Open "comc.1:19200,8,n,1" For Output As #1

Print #1 , "serial output"

 

'Now open a RECEIVE channel for input

Open "comc.2:19200,8,n,1" For Input As #2

'Since there is no relation between the input and output pin

'there is NO ECHO while keys are typed

 

Print #1 , "Press any alpha numerical key"

 

'With INKEY() we can check if there is data available

'To use it with the software UART you must provide the channel

Do

   'Store in byte

   B = Inkey(#2)

   'When the value > 0 we got something

   If B > 0 Then

      Print #1 , Chr(b)                         'Print the character

   End If

Loop

Close #2                                         'Close the channels

Close #1

 

End

 

After you have programmed the controller and you connected the serial cable, open the terminal emulator by clicking on   in Bascom.

You should see the program asking for an alphanumerical input, and it should print the input back to the terminal.