BS2 'hangs up'
Uwe
Posts: 18
I am using a BS2 as a timer, switching 10 output channels on and off in varying intervalls. The switched signal drives small 110V aquarium pumps.
Everything works great EXCEPT, every now and then the BS2 'hangs up', it stops in its sequence and needs to be reset.
I use the BS2 in conjunction with solid state relays and powered by a small 5V switching power supply.
All I can think of is that somehow noise gets into the circuitry and causes the BS2 to behave like that, but you tell me if I am right???
Uwe
Everything works great EXCEPT, every now and then the BS2 'hangs up', it stops in its sequence and needs to be reset.
I use the BS2 in conjunction with solid state relays and powered by a small 5V switching power supply.
All I can think of is that somehow noise gets into the circuitry and causes the BS2 to behave like that, but you tell me if I am right???
Uwe
Comments
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com
The code is exceedingly simple, I switch a pin on, pause for a while and switch it off. I use the BS2 as a timer.
I just found something which may or may not be related (probably isn't)
I have 270 ohm protection resistors connected to every pin.
When I trace my data lines with a logical probe I get shaky signals on some resistors.
I never even thought about resistors as causing trouble and I still don't understand why that would happen,, it is not a loose connection, but apparently the logic voltage level is not reached reliably.
Do I need to go and buy special 'digital resistors' ?
Uwe
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com
Do you have the catalog number of the Jameco power supply handy? Either that, or the manufacturer's name and catalog number? I'll see if I can find out if there's anything unusual about it for you.
Digital resistors - those are the ones that only come in the following values, right?
1 x 10^1, 1 x 10^2, 1 x 10^3, 1 x 10^4, 1 x 10^5, etc
Regards,
Bruce Bates
Post Edited (Bruce Bates) : 9/21/2005 2:54:07 PM GMT
The power supply is Jamecos order # 22 90 41.
The solid state relays I am using are Kyoto KB20C06A, Jamecos # is17 66 98.
I will post the code in a little while.
Uwe
The switching power supply (Jameco 229041) is an open frame switching DC power supply that appears to be reasonably well built. Load regulation is +/- 2% and line regulation is +/- 1%, which seems reasonably tight over the input range of 90-264 VAC 47-63 Hz, with an output of +5V @ 0-3A 15 watts. Ripple and noise is quoted at 50mV p-p. The unit carries all major agency approvals (UL, CUI, TUV, CE) and the board permits a voltage adjustment of 5%. Hold-up time is 16 ms and the efficiency is listed as 65%.
I don't see much that would cause a problem, or anything outstanding about it, but that hefty a power supply is a bit of overkill IMHO, unless you have other uses for it.
The SSRs (Jameco 176698) are not hockey puck style, but rather 4-pin solderable, SPST units. The input current vs. input voltage graph indicates an approximate apparent load of 4 mA at 5 volts which would be seen by the Stamp pin. The listed input voltage is 3-32 VDC and the output is rated at 6 amps @ 280 VAC max. The equivalent circuit definitely indicates internal photo-optical coupling line-to-load which drives a triac on the load side. The triac has an internal capacitor and resistor in series, parallelled across the load terminals. EMC directives (if appropriate) require the use of an external .22 uF capacitor across the load terminals. I note only for clarity that this is a DC input, AC output unit.
The SSR seems otherwise reasonably unremarkable. How the 220 ohm protection resistor might affect the driver LED is unknown, but it's probably suffice to say this unit will operate reliably down to 3 VDC, so I don't see that as a particular problem; albeit unnecessay.
Perhaps the analog gurus will see something that I don't. I have all appropriate datasheets for reference.
Regards,
Bruce Bates
You'd parallel the electrolytic and ceramic coming in because the electrolytic filters low-freq noise and power-draws, while the ceramic filters high-freq noise.
But this is mostly a guess. Another possibility is that switching power supplies do like a minimum load to help them regulate. The BS2 pulls so little (2 to 5 mA for itself) that this could be an issue. On the other hand, the spec does say full regulation down to zero amps -- so this shouldn't be an issue.
sequence0
high 0
pause 2000
low 0
high 1
pause 2000
low 1
high 2
pause 2000
low 2
high 3
pause 2000
low 3
high 4
pause 2000
low 4
high 5
pause 2000
low 5
high 6
pause 2000
low 6
high 7
pause 2000
low 7
high 15
pause 2000
low 15
high 14
pause 2000
low 14
goto sequence0
Not much to it.
But here is another tidbit of information.
This is a test setup and I have not wired all ten aquarium pumps to the ten output channels (lazy!).
I have only hooked up one or two and tested the other channels (while the stamp was running) by touching the wire of an additional pump to the various output channels.
It was then that the BS2 hang up.
Maybe I am causing the hangup thru my touching the output channel (the relay) with the wire, creating some ever so slight effect. The effect can't be big, the pumps draw 2-4 watts.
Could this be the reason????
Uwe
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax