4 replies to this topic

[65tux]

The bruise on my forehead is getting too big from pounding my head against the wall so I thought I would do a sanity check here.  Feel free to tell me I am crazy.

 

Using an ND+2 build 4.2.2 to send commands via uart to a display.  The display responds with a <cr> when the command has completed.  The symptom I am seeing is, whenever I send a serial command from "main" the response coming back from the display via the comm1_DataReceived event is immediate.  Whenever I send commands that are triggered by either an input interrupt or by data received from the display (touchscreen button push) the response from the display takes several seconds.  Because my code times out and moves on, I will get several responses all at once from the serial port buffer.  It is very repeatable and I can't see how it could be caused by the display, since again, responses to serial writes triggered by the "main" loop are always immediate.

 

Am I nuts?

 

[NooM]

//edit: removed, guess i understood that wrong.

[65tux]

Pretty sure I have all but proven it.  By putting all my code (send and receive) in one sub it works perfectly.  When using the DataReceived event handler receives are significantly delayed.

[CW2]

Do you have any synchronization (events, locking etc.) in your program? It sounds like the code in DataReceived event handler is blocking the other code, because it is expected to run on a different thread (?)

[65tux]

I assumed input interrupts were in a separate thread - is that not true?  If anything, it seems the other way around to me - the other logic is blocking the DataReceived.

 

The basic code is - when I get an interrupt, set a "waiting" flag and call a sub to send a command string to the display.  That sub has a whiile "waiting" loop.  The DataReceived will clear "waiting" when the response comes in.