Is it possible that the pcb has the 3.v and gnd reversed on the pads for the mcp3424? My pcb says 'ap2'. I purchased the bare pcb only.
Thank you,
William
Analog plug 3.3v and gnd reversed on mcp3424 footprint?
(14 posts) (2 voices)-
Posted 11/05/2010 14:47:18
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Whoa... could you email me a photo of it? I did indeed have a prototype batch where this was the case. I need to check whether it was also called AP2, but it sounds like I've got an old batch mixed up into the new ones :(
I'll check here later this evening. Thanks for pointing this out!
Posted 11/05/2010 15:03:04 -
Sorry but I'm away from the bench right now. I bought the pcb from Modern Devices last week . the lcd plug works good. the jeenode pcb was cut a bit too close to the wavy port 3 & 4 pads but I think I fixed that.
very cool set of boards !
William
Posted 11/05/2010 15:43:15 -
Ok, I've emailed Paul Badger of Modern Device - we should be able to quickly figure out what happened.
Yes, Paul mentioned your comment about this. It's not something I have seen or heard about before - with probably somewhere near 1000 JNv4's shipped by now. Here too, if you can spare the time, a photo would be appreciated so I can see just how bad it was on your board. The pcb's are designed with 12 mil clearance to the outside edge, but perhaps I should increase that a bit on the next revision.
Glad you like the JeeBoard family! :)
Posted 11/05/2010 17:07:30 -
Ok - looks like the AP2 board is indeed from a bad prototype run. You can check the EAGLE layout at
Posted 11/05/2010 21:48:10 -
Greetings,
Thanks, that is very kind of you. But I don't want you to go to needless shipping expense - I plan to order a few more items from Modern soon, so he can send me some them. Besides, I may try lifting those pins and soldering fly-wires tonite. I do have 3 of those boards total.
About the jeenode, I am no expert, but it seems obvious to me that the pcb board was cut in the wrong place -- notice the missing silkscreen on that entire edge of the pcb-- compare it to the other side, where there is a white 'box' around the port pins. The 'box' is missing on the port 3/4 side and you can see the pads are cut slightly also.
The reason I noticed, was that was the first pin that I tried to 'blink'. When I inspect the boards, I so a long metal 'burr' that was from an inner layer (I guess) and some of the pads were soldered to me (by me, by mistake).
After I removed the burr, the pad was disconnected, so I added a small wire from the cpu pin to the port pad. Here is the photo of both boards:
http://bvwelch.com/jeenode/jeenode004.jpg
Thank you,
William
Posted 11/05/2010 22:05:51 -
That JNv4 board is indeed seriously off. You should have a port outline rectangle on the back silkscreen all the way around.
And yes, you have the wrong AP2 boards. I'm sorry for the mixup. My offer for replacement stands (I use regular mail, takes some 5..8 days to the US, but postage for this is insignificant). Then again, feel free to resolve this with Modern Device, of course.
I'll keep an eye out for the way boards are cut. Thx.
Posted 11/05/2010 22:17:20 -
Good news - I modified the AP2 board to reverse power and gnd and it works! I put a few of your demos together to make a diag that displays channel #1 on serial and lcdplug: http://bvwelch.com/jeenode/try04.pde
During this early stage of development, I put the LCD on a separate bus from the AP2 board.
I'm liking these little boards!
Thank you,
William
Posted 12/05/2010 05:16:17 -
These little boards are working well for me. I'm recommending them to some other builders. Do you know if Modern has the updated/correct bare PCB in stock by now?
I would like an alternative to my I2c ambient sensor, that is cheaper and easier to solder. The best I've come up with so far, is to solder a 3-terminal analog sensor like the mcp9701 into the IRQ pad, but of course that isn't an analog pin on the Jeenode, so have to kludge around with an adapter or fly-wire to an analog pin. Any suggestions?
Funny - I just thought of another one- if I 'waste' one of the 4 channels, I can wire the ambient analog sensor to channel #4.
Posted 26/05/2010 05:45:59 -
Best thing is to check with Paul Badger of Modern Device about the board mixup - he's aware of the issue, I think everything has been resolved now.
Ambient temperature, right? How about the DS18B20 1-wire sensor? What range / accuracy? You could even hook up an NTC resistor. There are too many options out there for me to be able to make a decent choice - I've been using the SHT11 temp/humidity sensor for most room temp measurements. The Pressure Plug is also a good one, accurate to 0.1°C. Neither of them are cheap, though.
Posted 26/05/2010 12:48:43 -
Thank you for your reply. A temp-sensing device with a digital I/O would be great, but so far, the ones I've looked at are either too expensive or they are in a tiny SOT-23 package. So that is why I started looking at analog-output temp-sensing devices in TO-92 packages. Some of these are power-hungry but the mcp9701 is not bad.
Posted 26/05/2010 13:45:15 -
On the revised PCB, are the holes for the ADC channels on the 100 mil grid? If not, why not?
The PCBs I have (with the reversed pwr/gnd pins on the adc), don't line up-- if I solder the module down onto a generic prototyping PCB, the holes for the 'port' connectors line up fine, but the holes for the analog channel connector are off-grid.
Project:
Posted 28/05/2010 03:26:40 -
No, the ADC channels are halfway in between. Couldn't fit it in otherwise. Hm, you have a good point. I should have widened such a board by 0.1" to make more room.
I see that it's the same with many of the plugs.
My thinking at the time was that the port header would be pointing sideways or down, but the connector (for ADC signals in this case) would usually be pointing up or outwards. See also
There's not much I can do to change this right now. All I can say is that I've made a note to do all future revisions and boards with headers on a 0.1" grid. Even if that means widening them slightly.
Posted 28/05/2010 09:11:21 -
I like your JeeNode 'port' idea and your neat arrangement to daisy-chain the 'plugs' via your port connections very much, but in this case, I needed more room for the TC connectors, and I'm using the mcp9800 as the ambient sensor. I guess you could think of what I'm doing is making a 'thermocouple plug', using your adc plug as a building block.
Yes, I do see your neat plugs doing double-duty as break-out boards. Thanks for keeping the idea of a 100-mil grid for thru-hole connectors in mind for the future.
Posted 28/05/2010 10:24:56