Stamp Timing Puzzle

Humanoido

The stamp BS1 can only do one thing at a time. Each of 10 stamps need to report their ID number (using serout), while the others listen (using serin) and write all the numbers to eeprom. Each stamp does not know the other stamps. The ID numbers are approximately 0, 17, 28, 40, 49, 70, 89, 111, 116, 128.

I was thinking about some internal timer, and each computer talks in their time slot, and listens in the remaining time slots. Is there anything internal to the BS1 that can be read as a timing tick, while the program is running? I really don't have the resources to add ten clock chips although that would be a perfect solution.

Maybe there is a much more simple solution?

humanoido

slot   1        2        3        4        5        6        7        8        9        10
id     0        17       28       40       49       70       89       111      116      128
bs1    x
bs2             x
bs3                      x
bs4                               x
bs5                                        x
bs6                                                 x
bs7                                                          x
bs8                                                                   x
bs9                                                                            x
bs10                                                                                    x

dev/null

The Stamp chips do not have virtual timers that you can use. It's either timing chips or some other solution.

I had a similar problem, I needed a common "timer service" on my serial bus.

I set up a Javelin as a timer master. From my stamps I send "resettimer(x)" and "gettimer(x)" via SEROUT to the Javelin, which responds with elapsed time.

Currently I have three timers going, but you could in principle have unlimited numer of timers, with the Timer() object .
This is great because it allows me to have "virtual" timers going while I do my Stamp processing.
It might not suit your needs, but I thought I'd tell you anyway.

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dev/null

Humanoido

dev/null:

Thanks for the idea. I will create a fuzzy timer, set and controlled by the absolute computer. A precise timer is not necessary so a virtual fuzzy clock will work just fine. No parts necessary. The key here is not to poll the VR Clock but rather have the clock controller send out flags. Sort of like tuning your radio to WWV and listening for the incremental mark.

humanoido

achilles03

What do you mean "does not know the other stamps"? Do you mean that the IDs can vary? Or do you just mean that since they're on the same line, there's no way for them to know which stamp is transmitting without an identifier?

This solution would work if the other stamps can be programmed with the IDs of the other stamps on the line, then have them go in sequence like this:

---

STARTLOOP:
SERIN ID, data
WRITE ID, data to eeprom
if ID = target ID THEN TRANSMIT
GOTO STARTLOOP

TRANSMIT:
pause 1
serout ID, data
goto STARTLOOP

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Each stamp has a target ID, which is the ID of one of the other stamps. Also, instead of a target ID, you could just use a range.

Hope that helps,
Dave

dev/null

I think he is sharing the IO line and using flow control. So he's using only 1 pin for receive transmit...

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dev/null.