Problem 2 Propeller Activity Board

Discovery

The Propeller is outputting pulse trains on P0-P7 on one COG and they are solid...working properly.

The same Propeller is outputting pulse trains on P8-P11 on another COG but the pulses come and go. Some times they exhibit full pulse height then the pulse height drops, gets noisy, and goes to zero. Other times the pulses go to full scale...then sometime later the pulses form again. The variation is not the same for all pulses...mostly random from one pulse to another.

Has anyone encountered this problem before and have a solution?

Sincerely,

Discovery

Publison

Would you care to share the code so that we may load it up and try it?

Discovery

It would be really inconvenient to share the code since the work station is not accessible by the Internet.

I performed an experiment wherein the four output pins used by COG#1 (showing the instability problem) were switched with four output pins of COG#0. The instability switched with the COGs.

It appears to me that the input/output directions are not set properly. Does each COG have to set its I/O register? If so...how is it done using "C"?

For example in COG#1: high(8), low(9), low(10), low(11) [pins 8-11] would output pulse trains to turn a stepper motor but unstable.
In COG#0: high(0), low(1), low(2), low(3) [pins0-7] would output pulse trains to turn another stepper motor but these pulses are stable.

Switching pins(8-11) with pins(0-3) makes the pulses generated by pins(0-3) unstable.

Discovery