Flashing during ramp

[holtm]

I have assembled two 8 channel Renards (my own PCB design from the Renard 8 schematic) All works fine unless I ramp (up or down) then randomly (or so it seams) I get a drop out, or more frequently, a flash once or twice during a 3 second ramp. It happens inconsistently on some or all of the channels. I've read the wiki and the old forum and can't find an answer.
I’m using a setup similar to the Renard-T and Renard-8 (zero-cross from unfiltered DC)
I'm using the 20070907 firmware now. I tried previous versions with same effect. I think it may be reduced with the 20070907? (maybe just hopeful)

I thought maybe the board, but two act the same?
Any help would be appreciated.

[P. Short]

How is the firmware set up? Non-PWM, or PWM? Also, what SSRs?

--

Phil

[holtm]

Non-PWM firmware
MOC3022 opto (10mA with appropriate resistors), BTA06-400BRG Triac, very simular board to the Coop of last year (Sean Bowf)
The flash is like a strobe, very fast.

[holtm]

I just watched the lights for a while, I have vixen ramping up for 3 sec and then down for 3 and repeat. There were some cut-outs too, to black and then back to the ramp. If a packet is bad and the PIC waits for the next sync, do the lights turn on, off, or stay with the previous setting? Do you think it could be the computer?

[Wayne J]

I had the same issues. I used this firmware and it fixed it.
http://home.earthlink.net/~justswitch/renard-20070407c.asm

just make sure vixen plug-in is set to 57600 baud as well as the COM port.

(worked for me anyways)
8)

[holtm]

That is the firmware I started with. Your post reminded me that I forgot to say that I'm using the internal clock, I changed the _CFG line, BAUDRATE=19230 and CLOCKRATE=8000000.

I just did some more tests. With all channels off except of #8 which ramps up and down. Only channel 7 strobes when #8 is 80%-90%, not every time, just sometimes (about 1/2). I noticed this on both controller cards. Also, #3 stobes when #4 is ramping. I'll test some more tomorrow.

Thanks for the feedback.

[P. Short]

There are several things that might cause those symptoms.

Setting up more channels in Vixen than can be supported by the baud rate that you have selected. I put this first because it is the simplest to deal with...assign fewer channels to that plugin instance.

What lights are you using, and how is the wiring routed? In addition, are you ramping all of the lights at the same time, or just one (or a few at a time) and keeping the others constant (or off)?

Also, set the baud rate to 19200, not 19230. I don't think that it does any harm to use 19230, just that I never do it that way.

--

Phil

[holtm]

I tried 16 channels set up at 100ms. Same.

Lights are 100ct christmas lights from target. They are in a pile on the floor. The controller boards are in one case right next to the SSR and in case about 18" away. I've ramped some of them one at a time in some tests and all of them in others.
With one ramping, the one ramping cuts out while the channel one lower flashes. e.g. #7 on ramp #6 flashes on a separate test #6 ramping and #5 flashed.
I'll try baud rate next, but I'm sure the setting in the PIC ends up with a 25 either way. Maybe I'll try 9600.

Would a faster baud rate be better (ie should I get an osc)? Could the PIC be shutting down because of power and then restarting? I'm using the power from the ZC unfiltered DC, a 100mA regulator and 1000,10 and .1 uF caps.

[P. Short]

I'm not sure if I understand your comment about power.

If you are using unfiltered DC, the power supply should be first series diode (1N5817 or 1N5819 is best, but use 1N400x for starters if you don't have anything else), then after the diode a big cap to ground (I use 330 uF, but 1000 uF is fine), then the regulator (I use LP2950), then the other caps.

--

Phil

[holtm]

That is what I have, a diode 1N4004, 1000uF Cap, 78L05, 10uF Cap and .1uF cap. I asked the question because with a smaller initial Cap on the breadboard, the PIC would reset (or the regulator would shutdown) because the regulator couldn't keep the voltage up.

I'll post the board and BOM if you think it would be helpful.

I need to try
1. a different way to get RS232 to RS485, I wonder if there is some interference in the Renard-T (not exactly the same as Renard-T, but the same parts/function)

2. a different computer. maybe my computer's serial port is off a bit.

Unless you think it may not be the com.

Thanks again for the help!

[P. Short]

What are you using to generate the unfiltered DC? At this point I am as suspicious of power as of comms (or even more suspicious of power). The question really is whether the power on the PIC is stable, and how much ripple there is on it.

For now I'm busy with some family issues that may keep me away from the internet for a day or two.

--

Phil

[mel4853]

I hope that everything's ok with your family. . .

[holtm]

Thanks for your help already. You are the master. I too hope things are OK with your family.

I'm using a Radio Shack 12.6V center tapped transformer and two diodes. The Center tap is ground and the outside taps each go through 1N5395 diodes and then together. I put two sets of diodes in parallel so that I could split the power if needed and not overload the diodes. See board attachment.

[holtm]

UPDATE: After checking a bunch of things (thanks to Phil for helping) It is communications that is causing the problems. I bypassed my Max232 chip with a RS232 to RS485 adapter I bought from ebay and HEY, no problems.
I don't like it because is it not isolated. My MAX232 board used 6N137 chips to isolate the inside from the outside.
I'm guessing that I, being the novice, didn't get something right with the circuit design. If anyone wants to check it, it is attached.

[holtm]

Bump. Anyone have experience with 6n137 chips?

[P. Short]

I've been very busy with family matters, so I haven't had a chance to do much here. A few days ago I downloaded that schematic, and nothing really jumped out at me. The only think that I noticed is that the current on the output of the MAX232 is going to be fairly high with that small resistor, so I'd tend to look into that.

--

Phil

BTW, I have a little PCB with a 6N137 and ST485 chip on it for similar reasons (no MAX232, however, just a little transistor circuit that draws current from the DTR and RTS pins for additional diode current), and it seems to work fine.

--

Phil

[holtm]

Thanks, that gives me hope. I'll try a higher resistor there. I've seen some examples of a 1K there. Maybe I'll start there.

[holtm]

Update. The problem was in one of the 4 capacitors required for the MAX232. Got it fixed. In the mean time I swapped out resister R3 from 360 to 1K. R3 is a pullup (I think) resistor on the Vo side of the 6N137. It works either way. Is there an advantage to a larger resistor there. i.e. less power used.

[P. Short]

Good to hear, thanks for reporting back.

If it were up to me, I'd go even higher on R3, perhaps 4.7K Ohms.
--

Phil