Dangerous Prototypes

A couple of things I am working on. First up is the USB Toaster Oven Controller.  First rev of the PCB had silkscreen issues.  PCB size is 50mm x 50mm.





Just got these boards in.  Top is a 128x64 Graphics LCD Backpack.  PCB size is 73mm x42mm and attaches to the back of the Topway LM12864M.  It uses a PIC18F4550/4553 with 8 analog/digital, 6 digital I/O brought out to two connectors.  There is a daughter card for the Backpack with prototype area coming.

Middle is USB K Thermocouple Adapter. Bottom is USB PH Adapter.  Both are 30mm x 49mm and fit in the Serpac C-4 enclosure which is 55mm x 35mm x 15mm.



Here is a picture of the USB K Thermocouple Adapter in the Serpac C-4 enclosure.  The USB PH Adapter is the same size.


McZ

Nice PCBs, I really like the frog.

I'm eagerly following all the toaster oven reflow projects flying around :)

I got the rest of the parts today.  Looks like I have to get to work.

I am most excited about the 128x64 graphic backpack. 

I also have a couple hardcore Vinculum II projects coming up.

Have you done much with the Vinculum II's yet?  I've been running into a lot of firmware issues that make development somewhat challenging.

It is definitely quirky and the local (Taiwan) guys dont seem know much about it.  I have used the VNC1 and VNC2 is much better.  The documentation is a little lacking.  I have not had any issues so far but I have not gotten too deep into the USB Host stuff yet.

Any particular issues that you are having? 

McZ

I've been having quite a few issues.  The biggest is that in common situations it looks like an interrupt isn't serviced properly, making it continually fire and thus causing user code to run very slowly.

Also the USB host interface has a very limited API.  For instance, for control pipe requests, there is no way to determine how many bytes were actually received.

http://joshp.no-ip.com:8080/vnc2/ (http://joshp.no-ip.com:8080/vnc2/)

You are farther along than I am.  I was working with I/O and PWM assuming that the USB SW was mature.

Yeah, I assumed that too, but I think I was mistaken.  I was hopeful that things would stabilize over time, but the new firmware release appears to have broken more things than it fixed:

http://joshp.no-ip.com:8080/blog/micro/ ... redux.html (http://joshp.no-ip.com:8080/blog/micro/rock_band/vnc2_version140_redux.html)

I bought a bunch of these chips to use in a prototype  / Alpha test.  To say this device/toolchain is "immature" is being far too kind.  Some of the bugs are so glaringly obvious, for example on the devices I’ve got (32 pin variant) it requires pin 11 to be referred to as 199 for it to setup the IO correctly.  And mind you this isn't actually stated anywhere; I just stumbled across it looking at the output from the IOMUX wizard (which seems to do some weird things in itself.)

After two nights spent playing with a device I built a dev board for, I'm tempted to cut my losses here and go for a different manufacturer.

Perhaps I should also note that I compiled their "hello world" example, downloaded it, plugged in a LEXAR 4GB usb flash disk that I had just been talking to over the pre-compiled V2DAP firmware, and it destroyed it.  I honestly don't even know what it did, but windows or mac can no longer mount it as a USB device.  Seriously this is their example code!

I have put the FTDI projects on hold.  At this point I am not sure I care.

My projects with the VNC2 are on hold as well.  I'm hoping that a new firmware may fix enough that it becomes usable, but I am not holding my breath.

For non-mass production projects the extra couple of dollars to go to a fully fledged 32-bit processor with USB from one of the big names (like Microchip or Atmel etc.) is well worth it.  I just got a 32bit AVR and loving it, guess I'll try and ebay off the FTDI devices or do a youtube clip of there distruction.

For this particular project of mine, I need both a USB host and device.  I've also used the 32 bit AVR and find it fine, but am not sure I want to move up to needing two of them.

Same here.  I needed two host ports.

That is an advantage I don't see many other devices having.  Depending on how high a performance you need there's a number of 8-bit USB devices like the ATmega8U2 you could join with an AVR32 over SPI to give 2 USB ports.  Or even using the FTDI chip with one of the precompiled firmwares.  I've had the V2DAP running without issue, but obviously there's a fair performance hit compared to having two USB ports in the one device.

If you are talking multiple chips and cost there are lots of ways to go.
 
Two PIC24's. 
A PIC24 and a MAX3421E.
A pair of MAX3421E and a PIC12/16/18.

Or if FTDI gets their shit together, one VNC2.

I have used the VNC1 before but you cant program it.  It does what it is supposed to do but you have to have another processor to do all the work.

another option: USBizi chip (runs .net micro framework) will give you usb host and client ports, and you can use a USB hub to get as many USB devices as you need.  Depends more on what USB device profiles you might want..... but it can dp all your IO needs thats for sure!

I have a customer who spec's the project and as usual cost is a driving factor.  The VNC2 mets the cost factor and performance.  I am sure that FTDI will fix their compiler issues.  They just have to get the right programmers on the code.

Yeah, I was talking about non-mass production.  For low volume stuff the development cost would out weigh the cost difference of the extra uC.

I have been looking for an alternative to the traditional Olimex ICD 100 mil pitch Molex connector.  A 2mm pitch or smaller would save board space.  I was put off by the mating cycle specs.  The spec is 30 maximum.  I went back and looked at the spec for the original Molex connector and it is also 30 maximum.  They are a lot more durable than that so the smaller connectors should be better than 30 if you dont bend the pins.  I use 2mm pitch connectors for the Xilinx Pod and TI JTAG pod without any problems.  Going as small as 1.27mm is possible.

Comments?

I am looking at the Samtec TFM series (http://http://www.samtec.com/documents/webfiles/cpdf/TFM-1XX-XX-X-S-XX-MKT.pdf)  They have a pitch on 1.27 mm but are only slightly smaller than the Molex.  The part number for the header would be TFM-105-01-L-S.

the samtec TFM series you linked to appears to be rated for 1k mating cycles (with mated with the SFM series).  it's definitely a good move going wtih a connector that has a shroud for that small of a pitch (primarily because of the added mechanical stability).

i'm assuming you're doing board-to-board mating (i'm not familiar with the Olimex ICD)?

i thought samtec had some even tighter pitch connectors, i'll give a shot if i find something.

here's a 0.8mm socket from samtec:
http://www.samtec.com/ProductInformatio ... series=sem (http://www.samtec.com/ProductInformation/TechnicalSpecifications/Overview.aspx?series=sem)

i didn't immediately notice a spec on number of mating cycles, but they've always been really helpful over the phone and through email.

The Olimex ICD connector is the Molex 5/6 pin 100 mil pitch connector pretty much everyone uses.  The original had 6 pins but no one uses the PGM signal anymore so 5 pins.

here's something that might be worth considering, depending on the end application:
http://www.samtec.com/ProductInformatio ... series=SEI (http://www.samtec.com/ProductInformation/TechnicalSpecifications/Overview.aspx?series=SEI)

a 1mm centerline (single piece) connector. So, if you were using it on a programmer PCBA, you'd just need to supply pads on your target boards (no connector required).  couple this with a mechanical fixture to hold the target board in place (there are also alignment tabs and threaded insert options on that connector) and you wind up with super-low cost target boards.

pricing is around 2.90 USD for a 15 pin gold flashed connector (quan 1).

so you're doing cable to board. . .the links i sent are pretty much useless then.

so how's the reflow oven coming?  that's actually why i had originally started reading this thread:)

[quote author="bearmos"]so how's the reflow oven coming?  that's actually why i had originally started reading this thread:)[/quote]

First pass of PCB had issues with silk screen and footprints.  Fixed and sent out for fab.  Should have this batch back this week or early next week.

[quote author="bearmos"]here's something that might be worth considering, depending on the end application:
http://www.samtec.com/ProductInformatio ... series=SEI (http://www.samtec.com/ProductInformation/TechnicalSpecifications/Overview.aspx?series=SEI)[/quote]

Great I have been looking for something like that. Thank you.

excellent, honken.  i'm glad someone can use it, it looks like a very interesting connector.  i'll be curious to know how it works out for you, if you wind up using it.