Post by thread:[PIC]: ===== >B to C

Ok I am sending an on/off signal from a 16f876 Port C.2 to a 16f877 Port B.2 and my master program does not see it. The slave pic boards have been tested and work. Here is program I am using in MASTER Pic. What is to happen is Master signals Slave to run and Slave then signals Master when its done. Then Master goes to next section of code to run next Slave but not before last slave signals done. This program will cycle through everypart turning everything on and off but never waits for slave pics to signal its done. It just continues and runs all six sections. So for some reason it looks like the Master is not seeing the slave saying when its done. Where did I go wrong? Could something in my Epic programmer be set wrong? My wiring is like so. 16f877(Master) <------------------------[ 220 ohm ]----< 16f876(Slave) resistor is for zap protection line is only 14inches long. Here is program: ==================================================== ==================================================== @ DEVICE pic16F877, hs_osc, wdt_off, pwrt_off, bod_off, lvp_off,cpd_off,wrt_off, protect_off DEFINE OSC 20 '20 MHz crystal ' - - - -SETUP PORTA for OUTPUT- - - - - - - ADCON1 = 7 ' Set PORTA and PORTE to digital TRISA = %00000000 ' set PortA for all output PortA = %00000000 ' turn all lines on PortA OFF ' - - - -SETUP PORTB for INPUT- - - - TRISB = %01111111 ' sparein, trig, emer on PORTB to input Main_done var PORTB.0 ' Main Air Supply done line Clamp_done var PORTB.1 ' Clamp done line Index_done var PORTB.2 ' Index done line Tilt_done var PORTB.3 ' Tilt done line TV1_done var PORTB.4 ' Transverse1 done line TV2_done var PORTB.5 ' Transverse2 done line Counter_done var PORTB.6 ' Counter done line ' var PORTB.7 ' not used ' - - - -SETUP PORTC for OUTPUT- - - - TRISC = %00000000 ' set PortC for all output PortC = %00000000 ' turn off all portC Main var PORTC.0 ' Main Air Supply Valve Clamp var PORTC.1 ' Clamp Valve Index var PORTC.2 ' Index Valve Tilt var PORTC.3 ' Tilt Valve TV1 var PORTC.4 ' Transverse1 Valve TV2 var PORTC.5 ' Transverse2 Valve Counter var PORTC.6 ' Subract from Mechanical Counter ' var PORTC.7 ' not used ' - - - -SETUP PORTD for OUTPUT - - - - TRISD = %11110000 ' set PortD for 4 output & 4 input PortD = %00000000 ' turn off all portD ' - - - -SETUP PORTE for OUTPUT- - - - TRISE = %00000111 ' set PortE for all input PortE = %00000000 ' turn off all portE '-------------------------------------------------------- ' = = = = = = = = = = ' = TEST Program = ' = = = = = = = = = = test: Main = 1 'Master signals Slave to turn ON While Main_done = 0 'Wait till Slave signals that its done Wend Clamp = 1 'Master signals Slave to turn ON While Clamp_done = 0 'Wait till Slave signals that its done Wend Index = 1 'Master signals Slave to turn ON While Index_done = 0 'Wait till Slave signals that its done Wend Main = 0 'Master signals Slave to turn OFF While Main_done = 0 'Wait till Slave signals that its done Wend Clamp = 0 'Master signals Slave to turn OFF While Clamp_done = 0 'Wait till Slave signals that its done Wend Index = 0 'Master signals Slave to turn OFF While Index_done = 0 'Wait till Slave signals that its done Wend goto test = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Thanks Wrong Way Ray (Ray Choat) spam_OUTrcTakeThisOuTkenai.net -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam@spam@mitvma.mit.edu

Raymond Choat wrote: > >Ok I am sending an on/off signal from a 16f876 Port C.2 to a 16f877 Port >B.2 and my master program does not see it. The slave pic boards have been >tested and work. Here is program I am using in MASTER Pic. What is to >happen >is Master signals Slave to run and Slave then signals Master when its done. >Then Master goes to next section of code to run next Slave but not before >last slave signals done. > >This program will cycle through everypart turning everything on and off but >never waits for slave pics to signal its done. It just continues and runs >all six sections. So for some reason it looks like the Master is not seeing >the slave saying when its done. Where did I go wrong? >Could something in my Epic programmer be set wrong? My wiring is like so. > Depending on what your slaves are doing, I have to wonder what their 'finish' state is and how quickly they can respond to the next 'go' command. You may need a simple handshake between your main and slaves to ensure that each slave starts and *then* gives a valid 'done' response. If you issue the 'go', wait for 'not done', and then wait for the 'done' response, main will be able to check that each slave actually runs its process. Your main code may be proceeding on invalid 'done' signals. Regards, Bob _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

My slave (16f876pic board) runs a 24volt air valve. The Master (16f877) runs 6 of these slaves. The Master activates slave by signaling a LOW signal that was held high. This signal is working as each valve will turn on and off with the test program run. The Slave tells Master that it has finished (or end limit was reached) by sending a HIGH signal from its port C to the Masters port B. Signal is low when slave is busy and high when it is finished. I checked with digital probe and signals are correct. The signal to the slave is correct and signal back from slave is correct. So it must be how the Master sees this busy/finished signal from the slave. It seems simple what I am trying to do "Turn on slave and wait till slave is done, then continue". None of the signals timing or speed is real critical. Sometimes when the master activates the slave, the slave may already be in that position and the _done line will already show high (finished), never showing (low)busy. Here is a piece of the code that the Master uses to talk to slave. Does this piece of code require that it sees the "low" first then exits when it goes "high"? Main = 0 'Master signals Slave to turn OFF While Main_done = 0 'Wait till Slave signals that its done with a high signal Wend 'Then continue Is there a better way of doing this with PBP? {Original Message removed}

Raymond Choat wrote: {Quote hidden}> >My slave (16f876pic board) runs a 24volt air valve. The Master (16f877) >runs >6 of these slaves. The Master activates slave by signaling a LOW signal >that >was held high. This signal is working as each valve will turn on and off >with the test program run. The Slave tells Master that it has finished (or >end limit was reached) by sending a HIGH signal from its port C to the >Masters port B. Signal is low when slave is busy and high when it is >finished. I checked with digital probe and signals are correct. The signal >to the slave is correct and signal back from slave is correct. So it must >be >how the Master sees this busy/finished signal from the slave. It seems >simple what I am trying to do "Turn on slave and wait till slave is done, >then continue". None of the signals timing or speed is real critical. > >Sometimes when the master activates the slave, the slave may already be in >that position and the _done line will already show high (finished), never >showing (low)busy. Here is a piece of the code that the Master uses to >talk >to slave. Does this piece of code require that it sees the "low" first then >exits when it goes "high"? > >Main = 0 'Master signals Slave to turn OFF >While Main_done = 0 'Wait till Slave signals that its done with a high >signal >Wend 'Then continue > >Is there a better way of doing this with PBP? > Simple things between two (or more processors) are rarely as simple as they may appear to be. :=) No, your code does not require that the master see a low before it sees a high. What I'm suggesting is that it should be changed so that it does. The timing of the interactions between master and slave processors can create all sorts of problems that aren't immediately obvious. How quickly can a slave respond to the master's 'main = 0' port change? Unless it's instantaneous (or faster), a 'race condition' between the two processors can result. Since the slave has to detect the port change and can only then respond by dropping its '_done' line, your master processor can be checking the condition of the _done signal well before the slave has had any chance to drop it. In this case, _done doesn't just mean 'done', it also means 'not responded to yet'. If this happens, the master 'thinks' that the slave is finished when it had just seen the change command and had not yet responded to it. Without a clear indication from the slave that it has seen the command, the master can't know whether the _done indication is valid or not. By having the slaves go busy in response to every command, the master can 'see' the slave go busy. (At this point, the master knows that the command has been accepted by the slave.) The master can then wait for the _done indication when the slave completes its processing (or immediately if no processing is needed). Regards, Bob _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestKILLspam.....mitvma.mit.edu

> Ok I am sending an on/off signal from a 16f876 Port C.2 to a 16f877 Port > B.2 and my master program does not see it. Is that because it's not there or because the master has a bug? Look at the line with a scope or artificially create the signal with a switch. This will at least isolate the problem to the master or the slave. It seems pointless to go digging around in the code until you know which unit is having the problem. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, EraseMEolinspam_OUTTakeThisOuTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> Sometimes when the master activates the slave, the slave may already be in > that position and the _done line will already show high (finished), never > showing (low)busy. Here is a piece of the code that the Master uses to talk > to slave. Does this piece of code require that it sees the "low" first then > exits when it goes "high"? I haven't looked at your code, but it might be simpler to have a valve open/closed line instead of command busy/done line. That way you not only know when the slave has finished a command, but you also always know what state the valves are in. If the master ever commands a slave to open its valve and that valve is already open, then the slave will do nothing and the master sees the command completing immediately. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, olinspam_OUTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

My orignal code tracked the valve as to if it was open or not. But I need to know when the air cylinder reaches the end limit. When the slave sees this limit switch it turns on the _done line. Then I tried simpler code as in this "test" program and it still does not work. Here is my test code. @ DEVICE pic16F877, hs_osc, wdt_off, pwrt_off, bod_off, lvp_off,cpd_off,wrt_off, protect_off DEFINE OSC 20 '20 MHz crystal ' - - - -SETUP PORTA for OUTPUT- - - - - - - ADCON1 = 7 ' Set PORTA and PORTE to digital TRISA = %00000000 ' set PortA for all output PortA = %00000000 ' turn all lines on PortA OFF ' - - - -SETUP PORTB for INPUT- - - - TRISB = %01111111 ' sparein, trig, emer on PORTB to input Main_done var PORTB.0 ' Main Air Supply done line Clamp_done var PORTB.1 ' Clamp done line Index_done var PORTB.2 ' Index done line Tilt_done var PORTB.3 ' Tilt done line TV1_done var PORTB.4 ' Transverse1 done line TV2_done var PORTB.5 ' Transverse2 done line Counter_done var PORTB.6 ' Counter done line ' var PORTB.7 ' not used ' - - - -SETUP PORTC for OUTPUT- - - - TRISC = %00000000 ' set PortC for all output PortC = %00000000 ' turn off all portC Main var PORTC.0 ' Main Air Supply Valve Clamp var PORTC.1 ' Clamp Valve Index var PORTC.2 ' Index Valve Tilt var PORTC.3 ' Tilt Valve TV1 var PORTC.4 ' Transverse1 Valve TV2 var PORTC.5 ' Transverse2 Valve Counter var PORTC.6 ' Subract from Mechanical Counter ' var PORTC.7 ' not used ' - - - -SETUP PORTD for OUTPUT - - - - TRISD = %11110000 ' set PortD for 4 output & 4 input PortD = %00000000 ' turn off all portD ' - - - -SETUP PORTE for OUTPUT- - - - TRISE = %00000111 ' set PortE for all input PortE = %00000000 ' turn off all portE '-------------------------------------------------------- ' = = = = = = = = = = ' = TEST Program = ' = = = = = = = = = = test: Main = 1 'Master signals Slave to turn ON While Main_done = 0 'Wait till Slave signals that its done Wend Clamp = 1 'Master signals Slave to turn ON While Clamp_done = 0 'Wait till Slave signals that its done Wend Index = 1 'Master signals Slave to turn ON While Index_done = 0 'Wait till Slave signals that its done Wend Main = 0 'Master signals Slave to turn OFF While Main_done = 0 'Wait till Slave signals that its done Wend Clamp = 0 'Master signals Slave to turn OFF While Clamp_done = 0 'Wait till Slave signals that its done Wend Index = 0 'Master signals Slave to turn OFF While Index_done = 0 'Wait till Slave signals that its done Wend goto test = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = {Original Message removed}

Raymond Choat wrote: > >I have already tested the slave boards using a switch on input and an led >on >the output. Seems to work perfect. So I am 98% sure its in the MASTER or >Master Program. When the Master and Slave is hooked together and tested I >get correct signals also but the Master still does not "Pause" till _done >signal is recieved from slave. I have never had something so simple be >sooooo hard. >Wrong Way Ray (Ray Choat) > Don't be so convinced that you're doing something so simple that it just *has* to work. In theory, you are, indeed, performing a simple task. Back in the real world, however, getting 2 microprocessors (each running their separate programs at multi-megahertz rates) is not necessarily all that simple. Unless you can flip your switch in microseconds and see the LED light in the same microsecond kind of time frame, your manual test isn't doing anything close (speedwise) to what your master micro is doing. Your test may be comforting but its results are not a reflection of the 'real world' in which your system is operating. Getting a reliable command/response handshake going between your master and its slaves will go a long way toward resolving your problem. Regards, Bob _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Raymond Choat wrote: > >Got it fixed. Something you said gave me the idea to look more at my timing >of things. Then I got the idea that maybe the slave is not fast enough >putting the _busy signal to low (showing busy) that would have the Master >wait. So I just added the pause below and it worked. Thanks for bouncing >the >ball with me. > Glad to see that you got things working. As long as your speed requirements aren't particularly high, this approach will certainly work. Giving the slave enough time to recognize and respond to its incoming command will let your master always see a valid '_busy' signal. If you encounter a similar situation with tighter speed constraints, you may find that using a fixed delay is too slow to meet your comm requirements. In that case, a 'wait for busy', 'wait for not busy' handshake mechanism will allow communication to run as fast as your slaves will allow. Regards, Bob _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> I got the idea that maybe the slave is not fast enough >putting the _busy signal to low (showing busy) that would have the Master >wait. So I just added the pause below and it worked. > pause 100 ' pause allows slave to And towards that goal of fast, and reliable, what you can do without making it too complex is to write a loop that checks for that _busy signal to change, but is limited by a count. So that if the signal never went busy, you loop would just wind up running for "100", but if the signal changed while the loop was polling, it would exit immediately and thus not slow things down any more than necessary. Barry -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Thanks for the idea, I will consider it. Thanks Wrong Way Ray (Raymond Choat) ----- Original Message ----- From: "Barry Gershenfeld" <@spam@barryKILLspamZMICRO.COM> To: <KILLspamPICLISTKILLspamMITVMA.MIT.EDU> Sent: Tuesday, August 21, 2001 10:18 AM Subject: Re: [PIC]: ===== >B to C {Quote hidden}> > I got the idea that maybe the slave is not fast enough > >putting the _busy signal to low (showing busy) that would have the Master > >wait. So I just added the pause below and it worked. > > pause 100 ' pause allows slave to > > And towards that goal of fast, and reliable, what you can do without > making it too complex is to write a loop that checks for that _busy > signal to change, but is limited by a count. So that if the signal > never went busy, you loop would just wind up running for "100", but > if the signal changed while the loop was polling, it would exit > immediately and thus not slow things down any more than necessary. > > Barry > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics