I think this is more finger trouble than PE simulator issue, but here goes...
I'm making a project for RS-485 Pelco-D CCTV control. The relevant part is I need to transmit onto the multidrop RS-485 bus, and will use a simple transmission collision avoidance strategy. I've used hsersetup to listen to the bus - not interested in the actual data, just reception of something/anything. When I'm ready to transmit, I check hserin to read the buffer: if there is something in there, run a short delay and check again. If the buffer becomes empty I'll transmit ... imperfect but simple first-line collision avoidance. (The nature of Pelco-D traffic is relatively infrequent 7-byte bursts, so there is a very good chance of finding a gap this way)
To test my code I would like to simulate an empty hserin buffer - M2 part. When using the PE simulator, when the hserin line is encountered we get a prompt box for data input. For my 'no traffic' condition, I want to just cancel or X-close this box and leave the virtual hserin buffer empty. I'm using the common method of pre-loading a word variable with FFFF and testing to see if hserin changes it to a byte sized value (which could be 00FF).
I just can't make that work. X-closing the dialogue box results in variable being set to 0000, not left at FFFF as I hoped.
I suppose what I need is like 'simulate timeout', but that option is greyed out for simulator hserin M2 flavour.
sample code to try in simulator
#picaxe 14M2
hsersetup B4800_4, $00 ;
loop:
w0 = $FFFF ;
hserin w0 ;
if w0 = $FFFF then ' unchanged, no data in buffer
' here I would do my thing
else
' something in buffer, so just wait a bit
pause 50; ' don't care if buffer overflows here
endif ;
goto loop ;
If I have on some previous try put some valid data in the hserin dialogue box, that seems to get stuck in the buffer, and gets re-read even if I cancel the dialogue box.
Am I misunderstanding that hserin should automatically 'pop' the data byte each time it is read out?
I'm making a project for RS-485 Pelco-D CCTV control. The relevant part is I need to transmit onto the multidrop RS-485 bus, and will use a simple transmission collision avoidance strategy. I've used hsersetup to listen to the bus - not interested in the actual data, just reception of something/anything. When I'm ready to transmit, I check hserin to read the buffer: if there is something in there, run a short delay and check again. If the buffer becomes empty I'll transmit ... imperfect but simple first-line collision avoidance. (The nature of Pelco-D traffic is relatively infrequent 7-byte bursts, so there is a very good chance of finding a gap this way)
To test my code I would like to simulate an empty hserin buffer - M2 part. When using the PE simulator, when the hserin line is encountered we get a prompt box for data input. For my 'no traffic' condition, I want to just cancel or X-close this box and leave the virtual hserin buffer empty. I'm using the common method of pre-loading a word variable with FFFF and testing to see if hserin changes it to a byte sized value (which could be 00FF).
I just can't make that work. X-closing the dialogue box results in variable being set to 0000, not left at FFFF as I hoped.
I suppose what I need is like 'simulate timeout', but that option is greyed out for simulator hserin M2 flavour.
sample code to try in simulator
#picaxe 14M2
hsersetup B4800_4, $00 ;
loop:
w0 = $FFFF ;
hserin w0 ;
if w0 = $FFFF then ' unchanged, no data in buffer
' here I would do my thing
else
' something in buffer, so just wait a bit
pause 50; ' don't care if buffer overflows here
endif ;
goto loop ;
If I have on some previous try put some valid data in the hserin dialogue box, that seems to get stuck in the buffer, and gets re-read even if I cancel the dialogue box.
Am I misunderstanding that hserin should automatically 'pop' the data byte each time it is read out?
