I'm working on my first application using Picaxe's.
At this moment I only have very minimal resources at my disposal (@winter quarters), so I cannot experiment too much myself. Reason for this post to pick your collective brains.
I will have two PCB's each with an 18M2. For the UI, they both need to drive one dedicated line each on a serial 16x2 OLED display (AXE133Y). The two 18M2's obviously will not mix transmissions.
Individual programs work and simulate well using the simulated serial LCD display. (Kudos to whom designed that)
My plan is to OR the two B.0 (TXD) pins of the 18M2's using 1K? resistors then go to the OLED, to stop the outputs fighting each other. I'm using the SEROUT B.0 command to send data to the display. I also init the B port by using DIRSB = %00011110, so the B.0 is set to input in both programs but that does not seem to matter in the simulation. I don't have a scope right now to put on that pin and look at the activity.
My assumption is that I need to assert the DISCONNECT command on both to avoid the output of one 18M2 forcing the other in programming mode.
I plan on using a two-way jumper to switch B.0 between the in-circuit programming connector and the one going to the display used during the actual running of the application, but that may be overkill.
Can anyone share any wisdom on the ORing method?
Tks, Paul
At this moment I only have very minimal resources at my disposal (@winter quarters), so I cannot experiment too much myself. Reason for this post to pick your collective brains.
I will have two PCB's each with an 18M2. For the UI, they both need to drive one dedicated line each on a serial 16x2 OLED display (AXE133Y). The two 18M2's obviously will not mix transmissions.
Individual programs work and simulate well using the simulated serial LCD display. (Kudos to whom designed that)
My plan is to OR the two B.0 (TXD) pins of the 18M2's using 1K? resistors then go to the OLED, to stop the outputs fighting each other. I'm using the SEROUT B.0 command to send data to the display. I also init the B port by using DIRSB = %00011110, so the B.0 is set to input in both programs but that does not seem to matter in the simulation. I don't have a scope right now to put on that pin and look at the activity.
My assumption is that I need to assert the DISCONNECT command on both to avoid the output of one 18M2 forcing the other in programming mode.
I plan on using a two-way jumper to switch B.0 between the in-circuit programming connector and the one going to the display used during the actual running of the application, but that may be overkill.
Can anyone share any wisdom on the ORing method?
Tks, Paul
