Strange Prop ProtoBoard problem
Harley
Posts: 997
I have a design which uses two Propellers. Initially last year I used solderless breadboarding to set up part of the design. It interfaces to some TTL logic. I use a TV monitor to view various Prop 'register' usage and serial input.
When the Propeller ProtoBoard became available I ordered several and am beginning to set one up with a 40-pin DIP Prop and its own EEPROM for the 2-Prop program. The first s/w demo I ran on it was the Dscope 'logic analyzer'. Which ran fine. I also am using another ProtoBoard for Dscope use, which runs fine too; so does the solderless breadboard.
Now the weird part. The original breadboard works fine with the 2-Prop program. So does the 2nd ProtoBoard work with the 2-prop program. But the first ProtoBoard I have added parts to for the 2-Prop doesn't display anything except for a initial flash of some junk. Doesn't even look like any textual stuff; unless it is just running once through a loop, then quits. By the way, none of the sockets for the second Prop or EEPROM are connected yet.
By the way, I'm using the first Prop to generate a 5 MHz for the 2nd Prop and that signal appears to be running in its own cog OK.
I can download (F11) the same 2-Prop program to all three, but the board I'd planned to use doesn't display anything after the initial flash of light on the screen.
Does anyone have a clue what could be wrong and where to check for this problem? It's got me buffaloed!
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Harley Shanko
h.a.s. designn
When the Propeller ProtoBoard became available I ordered several and am beginning to set one up with a 40-pin DIP Prop and its own EEPROM for the 2-Prop program. The first s/w demo I ran on it was the Dscope 'logic analyzer'. Which ran fine. I also am using another ProtoBoard for Dscope use, which runs fine too; so does the solderless breadboard.
Now the weird part. The original breadboard works fine with the 2-Prop program. So does the 2nd ProtoBoard work with the 2-prop program. But the first ProtoBoard I have added parts to for the 2-Prop doesn't display anything except for a initial flash of some junk. Doesn't even look like any textual stuff; unless it is just running once through a loop, then quits. By the way, none of the sockets for the second Prop or EEPROM are connected yet.
By the way, I'm using the first Prop to generate a 5 MHz for the 2nd Prop and that signal appears to be running in its own cog OK.
I can download (F11) the same 2-Prop program to all three, but the board I'd planned to use doesn't display anything after the initial flash of light on the screen.
Does anyone have a clue what could be wrong and where to check for this problem? It's got me buffaloed!
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Harley Shanko
h.a.s. designn
Comments
Is that normal for PLL16x, one cog used to generate 5 MHz, and two FullDuplexSerial channels (no signals in or out)?_____
Sure doesn't make sense to me that one Prop doesn't output proper video.
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Harley Shanko
h.a.s. designn
Still ProtoBoard #1 is bad, but #2 works!!
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Harley Shanko
h.a.s. designn
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Paul Baker
Propeller Applications Engineer
Parallax, Inc.
Post Edited (Paul Baker (Parallax)) : 2/28/2007 9:25:15 PM GMT
Was running my fingers around the Props tie-points and the program started. Must be an input floating differently on one ProtoBoard than the other, where #2 always started, yet #1 didn't (not without touching those pads around the Prop/EEPROM/crystal/reset switch area.
So, now to investigate which input(s) might be the culprit. Thanks Paul for the reply.
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Harley Shanko
h.a.s. designn
The two Props uses FullDuplexSerial to communicate w/each other. Apparently on ProtoBoard #2, that line being open, appeared at a high level. But Prop #1 must have appeared at a low level and hung it up. (A24 was the Rx input pin.)
A simple pull-up R on A24 now lets it always initialize and run properly. Ah, YES, CMOS can do that to you, whereas TTL usually appears high if open!
Case closed. Another lesson learned; a circuit not completely and properly interfaced MAY not work properly!
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Harley Shanko
h.a.s. designn