Smart pin mode 01110 (periodic/continuous: increment on A-rise) strangeness
wmosscrop
Posts: 409
in Propeller 2
The attached code will cause pin 1 to count the a-rises of pin 0, at about 100 per second, as output from debug.
If I change SP_SECTOR_UPDATE_TIMER to pin 1 instead of pin 0, pin 1 will still cycle, but pin 2 will not count the a-rises (the rdpin value is always 0). This seems to happen for any pin other than 0.
According to the documentation, pin selection %0101 selects the previous pin's input value. So in order for this to work for pins other than SP_SECTOR_TIMER = 0, I have to jumper that pin to the next pin. This fixes the issue with the counting.
But why does it work for pin 0 and 1 without the jumper? I have a eval board rev. B.
Comments
The input select for the counter is set to -3 rather than intended -1. Which means, when on pins P0/P1, you are counting the tx data of debug output.
I recommend start using the built-in symbols as per the Spin docs: eg:
wrpin ##P_COUNT_RISES | P_MINUS1_A, #SP_SECTOR_UPDATE_COUNTThis works
wrpin ##P_MINUS1_A | P_COUNT_RISES,#SP_SECTOR_UPDATE_COUNT
Are you saying that it doesn't work for pin 3 counting the rises with SP_SECTOR_TIMER set to 2?
From the current Parallax Propeller 2 documentation on p76:
Below is a diagram of a single I/O pin circuit. It is powered from its local 3.3V supply pin. It connects to its own pin, as well as its odd/even adjacent pin. Pins P0 and P1 see each other's pins as adjacent pins, as do P2 and P3, etc.
italics added.
Edit: Not so relevant here. I only looked quickly while at work.
Three of us at once!
The value I used for the input selector is from the @JonTitus smart pin documentation (Smart Pins Rev 5).
Page 6, under "WRPin"...
"x101 = read state of P37 - 1 = P36, pin number minus 1"
So it should be x111? Which does make more sense to me, being that all ones normally represents -1.
Edit: For some reason I can't get the @JonTitus link to work.