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Messages - alanh

32
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
The part number you have for the cap is rated at 6.3V.  Caps will de-rate as a function of temperature over time.  Most engineers use a 2/3 voltage ratio when sourcing parts.  I work in the automotive industry which is particularly rough on parts and we always use 50%.  At 6.3V there is a 20% de-rate margin - which is fine for a computer which isn't going to be used a lot.  However Jeff has mentioned he's shipped these boards all over the world.  Quite a lot of them to facilities and users who are trying to keep legacy industrial and medical equipment running.  Who knows what environment they will be in.  Thus I like to over-engineer things for a worst case I probably can't envision.  But again, this ultimately depends on what Seeed fulfillment has available.  For buying 1 for a proto-build, it's worth the extra pennies.  Moving up to 5mm body or MLCC gives more choice and more reliability respectively, but both affect cost.
35
Project development, ideas, and suggestions / Re: XT-IDE adapter with CPLD builds
Was going to order the parts kit.  I'm attaching my BOM for the proto build.  Couple observations:

- CSEL isn't connected.  It should be connected to ground.  This should be easy enough to fix with a solder bridge though

- The 47uF cap is hard to find in a 4mm tin with at least a 10V rating.  I'm not sure why this is even electrolytic as 1206 47uF caps are common and cheaper.  But this really depends on the parts availability from Seeed fulfillment.

- Driving all the pull-ups/jumpers from 3.3 will save a few milliamps.
41
Project development, ideas, and suggestions / Re: Madelon LPC development board
Both are supported under Linux.  I have a cross compiled arm-none-eabi-gdb taking to one right now.  Did you even look at my link above?  Yes you have to add some udev rules to prevent udev from automatically acting on the class.  It does work.

While I agree it would be less of a pita to build a extended remote target into a device, there are options today.  Though I would prefer your version since it's one less command I have to run.
42
Project development, ideas, and suggestions / Re: Madelon LPC development board
I'm still trying to figure out the difference in st-link (real or a clone) verse what you are proposing.  Both speak a simple command protocol over a CDC/USB device bridge to access SWD.  It sounds like the only difference is yours would speak the GDB extended remote protocol verses needing a translator to go from that to ST's encapsulation protocol.  Sounds like it would only impact eclipse users and I'm still unsure why you couldn't just change the host software and not the device.  But sounds like you have it worked out.  g/l!
43
Project development, ideas, and suggestions / Re: Madelon LPC development board
[quote author="Squonk"]
Yes, it's a USB 2.0-compatible full speed device @ 12 Mbps full speed. Anyway, the high speed 480 Mbps is almost useless on a 72 MHz microcontroller.
[/quote]

Didn't say it wasn't.  Was just clarifying as most people read 2.0 = 480 Mbps.  And 480 Mbps is useful on a MCU if you are just moving data from point A to B with DMA - eg. via a FIFO, EMI, 4/8 bit SDIO, etc; if your controller has such interfaces.


[quote author="Squonk"]
I was thinking of implementing an free/open serial (over USB CDC) SWD gdbserver, so if you have 2 of these boards, you can debug your project with the other one and using only completely free tools, such as Yagarto...
[/quote]

Like st-link?  Using gdb under Linux to load code into RAM, run it with break/watch, and never touch flash is one of the main reasons I'm a new big fan of M3/M4s.

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