[TriEmbed] Logic Analyzer Recommendatio

Sun Jan 18 12:17:52 CST 2015

The bp and the sl have a lot of overlap, but the bp is a "jack of all trades", whereas the sl really excells at logic analysis. I dont remeber numbers off the top of my head, but the sallae has much more processing power and offloads all the "analysis" part to the connected pc. If you ever actually need to drive an i2c bus from your pc, the bus pirate is really good at that. Disclosure,  I sell bus pirates, but I'm out of stock currently. I plan to get more soon.

The sallea software is pretty nice too, with thr bus pirate, you ussualy write a python script to interact,  or use a serial terminal. 

One nice thing I use my logic analyzer for is debugging.  Instead of turning on an led, I can use a spare io line or two to indicate software status,  and use that to trigger the logic capture. Ive caught race conditions in my code I never would have found otherwise.

Hope that helps.  I have no connection or affiliation to Sallae, but I think they make good stuff.

-Jon

<div>-------- Original message --------</div><div>From: Chip McClelland <chip at mcclellands.org> </div><div>Date:01/18/2015  11:54 AM  (GMT-05:00) </div><div>To: triembed at triembed.org </div><div>Subject: Re: [TriEmbed] Logic Analyzer Recommendatio </div><div>
</div>To all,  thanks for the responses thus far. I have one other question before I pull the trigger on this.  Does the Saleae doe enough extra to justify the extra price over the Bus Pirate?   My main focus today is listening to the I2C bus but am open to getting a more capable tool if it may be helpful in the future.

Thanks,  
Chip 

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Today's Topics:

   1. Re: Logic analyzer recommendation (Jon Wolfe)
   2. Why Did This Stop Working? (Grawburg)
   3. Re: Why Did This Stop Working? (Shane Trent)

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Message: 1
Date: Sat, 17 Jan 2015 14:48:32 -0500
From: Jon Wolfe <jonjwolfe at anibit.com>
To: Chip McClelland <chip at mcclellands.org>, "triembed at triembed.org"
        <triembed at triembed.org>
Subject: Re: [TriEmbed] Logic analyzer recommendation
Message-ID: <6d7mvm2pv0sfnbymgj40tcwp.1421524112170 at email.android.com>
Content-Type: text/plain; charset="utf-8"

I highly recommend the Sallae. I have a clone, ?that I actually received by accident, sort of. It has saved me many times. I will purchase an original one when I can afford it.

<div>-------- Original message --------</div><div>From: Chip McClelland <chip at mcclellands.org> </div><div>Date:01/17/2015  11:40 AM  (GMT-05:00) </div><div>To: triembed at triembed.org </div><div>Subject: [TriEmbed] Logic analyzer recommendation </div><div>
</div>To all,

I am trying to troubleshoot an issue with multiple devices on an i2c bus. Do any of you have a recommendation for an inexpensive logic analyzer that I could use to troubleshoot?? Ideally it would be able to look at SPI and simple digital and analog lines. Mac compatibility is a must. Any recommendations?

Adafruit has a Sallae 4-channel analyzer that is my current front runner but don't want to spend $100 and find out it is not the best choice. ?https://www.adafruit.com/products/2312
Thanks,

Chip

--
Sent from my iPhone - please excuse the typos
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Message: 2
Date: Sat, 17 Jan 2015 15:21:15 -0500
From: Grawburg <grawburg at myglnc.com>
To: Triangle Embedded Devices <TriEmbed at triembed.org>
Subject: [TriEmbed] Why Did This Stop Working?
Message-ID: <8beae92832cea269a16b8bc3c1481ef2 at myglnc.com>
Content-Type: text/plain; charset="utf-8"

My train/conveyor project developed a glitch when I redid the protoboard I was using.? The key to the project was an pair of IR LED emitter/detectors (Sparkfun SEN-00241) that until the rework operated just fine when 4.5 inches apart. Both units were inside of 1/2" tubes so that room lighting did not affect them. ? Circuit is attached. (I'm using 3.3 VDC)

Now, here's the one change -- and it's actually due to an original mistake.? The schematic shows a 10k resistor going to the collector of the detector. That's what I thought I had used on the original board (the one that worked) but discovered I actually had a 100k. My new board does have the 10k and what is happening is that instead being able to have the emitter/detector work at 4.5" they only work at about 2". Meaning that voltage goes to Vout which is a pin on my MCP23008 port expander when the devices are much beyond 2 inches apart.

Thanks,
Brian Grawburg

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Message: 3
Date: Sat, 17 Jan 2015 15:05:00 -0800 (PST)
From: "Shane Trent" <shanedtrent at gmail.com>
To: "Grawburg" <grawburg at myglnc.com>
Cc: Triangle Embedded Devices <triembed at triembed.org>
Subject: Re: [TriEmbed] Why Did This Stop Working?
Message-ID: <1421535900007.e33dcb59 at Nodemailer>
Content-Type: text/plain; charset="utf-8"

Brian,

Just change back to the 100k. The larger resistor provides a weaker pull-up and makes it easier for your IR signal to turn on the photo-transistor and pull down the output signal. The higher value of the 100k will make your sensor more sensitive to external light sources. But it sounds like your light shield on the ?detector is keeping out any extra light. Just be careful in the future if you start getting false triggers due to new light sources or moving the track to a new location.?

Another option would be using a smaller value resistor on your LED but you must stay under the LED current limit. I recommend the 100k pull- up since you already know it works.?

Shane

?
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