Top  Previous  Next


Returns the ASCII value of the first character in the serial input buffer.




var = INKEY()

var = INKEY(#channel)





Byte, Integer, Word, Long or String variable.


A constant number that identifies the opened channel if software UART mode


If there is no character waiting, a zero will be returned.

Use the IsCharWaiting() function to check if there is a byte waiting.


The INKEY routine can be used when you have a RS-232 interface on your uP.

The RS-232 interface can be connected to a comport of your computer.


As zero(0) will be returned when no character is waiting, the usage is limited when the value of 0 is used in the serial transmission. You can not make a difference between a byte with the value 0 and the case where no data is available.

In that case you can use IsCharwaiting to deterimine if there is a byte waiting.



See also






'name                     : inkey.bas

'copyright                : (c) 1995-2005, MCS Electronics

'purpose                  : demo: INKEY , WAITKEY

'micro                    : Mega48

'suited for demo          : yes

'commercial addon needed  : no



$regfile = "m48def.dat"                                   ' specify the used micro

$crystal = 4000000                                         ' used crystal frequency

$baud = 19200                                               ' use baud rate

$hwstack = 32                                               ' default use 32 for the hardware stack

$swstack = 10                                               ' default use 10 for the SW stack

$framesize = 40                                             ' default use 40 for the frame space


Dim A As Byte , S As String * 2


 A = Inkey()                                             'get ascii value from serial port

's = Inkey()

If A > 0 Then                                           'we got something

    Print "ASCII code " ; A ; " from serial"

End If

Loop Until A = 27                                           'until ESC is pressed


A = Waitkey()                                             'wait for a key

's = waitkey()

Print Chr(a)


'wait until ESC is pressed


Loop Until Inkey() = 27


'When you need to receive binary data and the bibary value 0 ,

'you can use the IScharwaiting() function.

'This will return 1 when there is a char waiting and 0 if there is no char waiting.

'You can get the char with inkey or waitkey then.