How do I implement a cog watchdog

BillDer

I am using BS2 function's "debugin" to get input. However, I would like it to time out if the user doesn't enter their name.
inside the code it has a reference to implement a cog watchdog, using the example... but I don't see the example.
Does anyone know how to do this?
Thanks in advance

Mike Green

It's much easier to modify DEBUGIN so it uses a timeout based on the system clock. You don't really need a separate cog. DEBUGIN uses SERIN_CHAR which has the following two lines:

    waitpeq(Mode << PIN, |< PIN, 0)                        ' Wait for idle
    waitpne(Mode << PIN, |< PIN, 0)                        ' WAit for

These are used because they put the cog running them into a low power state, saving power. They're equivalent to the following loops:

    repeat until (Mode << PIN) & |< PIN                    ' Wait for idle
    repeat while (Mode << PIN) & |< PIN                  ' Wait for beginning of start bit

To add a timeout, define another local variable "time" after "BR" in the declaration of SERIN_CHAR and define a constant "timeOut" at the beginning of the object in one of the CON sections like "timeOut = 10000" for a 10 second timeout between characters. You'd then do:

    waitpeq(Mode << PIN, |< PIN, 0)                        ' This could still be used since it waits for idle
    time := CNT                                                      ' Save start of timeout period
    repeat while (Mode << PIN) & |< PIN                  ' Wait for beginning of start bit
        if (CNT - time) > timeOut*(CLKFREQ/1000)      ' Has timeout (in milliseconds) expired?
            return -1                                                   ' Return a -1 to indicate that a timeout occurred

Note that you also have to modify the SERIN_DEC, SERIN_STR, and other SERIN_ routines to use a -1 as a buffer terminator in addition to a return (13) code or they'll store the -1 in the buffer (as a 255) and keep calling SERIN_CHAR which will continue to timeout thus filling up the buffer.

Also note that the timeout is limited to about 50 seconds with an 80MHz system clock.

BillDer

Thank you, that was exactly what I needed to know. I was a little worried about modifying the bs2 code, but I see how it works now.
Thanks again!!!