Now what would be REALLY great, is tweaking the existing eagle files to provide a more convenient way to pull PORT_EN high for xilinx programming.
The simplest procedure I came up with is to get the software all ready to go on the laptop so you just need to press enter, clip a jumper onto the vcc pin to the programmer, and touch the other end to one side of one of the resistors. It only requires one hand to hold the probe on the resistor if the other end is clipped to the vcc pin, so you have a hand free to tap the enter key. The spot that you have to touch is tiny, and pretty close to other spots that you absolutely should not touch, since the result would be to short out the on-board 5v-to-3.3v voltage regulator. Touching the wrong side of that very resistor would do that, and that's easy to do. It would be great to have a dedicated pad to touch a probe to. Could be as simple as simply extending the existing resitor pad a little on that side to make a better target to touch. Or in a luxurious world, a set of pins to stick a jumper onto like the write-enable jumper on figtronix, but there is precious little real-estate available for that. Clipping the lead onto the vcc pin is a little finnicky too. There is just barely enough pin length to contact the board, the clip, and still let the programmer wire grip the pin. Maybe it would be possible to insert a small through-hole for both VCC and PORT_EN, so that you could just stick a wire or pre-made jumper lead in both holes. Maybe you'd have to pull sideways on the wire a little to maintain solid contact while programming. One advantage to that way would be you could put the wire in place while there was no power to the board, so that there is no danger from touching the wrong parts on the way in. And it would be nice to have github hosted versions of the cad files so that you could have separate versions for 100 and nec. That way the 100/102 version could come with the half-holes already cut to the right size by the router path instead of having to sand each board down by hand without wrecking the board. -- bkw On Tue, Sep 19, 2017 at 7:40 PM, Brian White <bw.al...@gmail.com> wrote: > That would be awesome. > > One update to the pics and stuff I have so far, During the xilinx > programming stage, I used a chip carrier socket in a breadboard, powered by > a 5v wall wart, because I happen to have a bunch o those sockets. I'll send > you a socket or a few if you want, but I would say, ditch that and just use > a M100 itself to power the board for xilinx programming. You need a M100 to > do the final flashing anyway, not to mention testing, so it's a no-brainer, > just pop it in the m100 and let the m100 supply the 5v to the board. > Perfectly fitting socket and 5v supply ready made. > > > On Tue, Sep 19, 2017 at 4:48 PM, Josh Malone <josh.mal...@gmail.com> > wrote: > >> I'm willing to take a stab at building a REX. I think the only tool I'll >> need to acquire for assembly is the proper Hakko tip for drag-soldering. >> However, I don't have the Xilinx programmer, so I'll have to get my hands >> on one of those. They're <$30 shipped from China but that puts it in my >> hands in around a month, so nothing will be quick. (Darn - would have made >> a great RetroChallenge entry :) >> >> My disposable income these days is significantly less than my available >> time, so I'll just throw this offer out there: >> >> If 1 or 2 persons want to help cover the initial costs of the parts and >> tools, I'll build them a REX. >> >> A quick estimate says a run of 3 boards will cost me <=$140. I'm, of >> course, willing to throw in some of my own money, so I'd be looking for $50 >> per board from 2 contributors. >> >> I've done lots of soldering and even some SMT assembly (though not this >> fine) before, so I'm pretty confident I can pull it off. I'm not sure how >> long it would take to get everything together and then actually build it. I >> think the risk of failure is pretty low, but you're not willing to see your >> $50 disappear in the event that I completely screw this up, don't >> volunteer. :) >> >> If you're still interested after reading this, please contact me >> off-list. In the (possibly likely) event that I get >2 interests, I'll just >> choose randomly from the pool; I'm not willing to commit to >3 units until >> I've done this a time or two. I'll post on this thread when "orders" are >> closed. >> >> Thanks, >> >> -Josh >> >> >> On Tue, Sep 19, 2017 at 2:46 PM, John R. Hogerhuis <jho...@pobox.com> >> wrote: >> >>> >>> On Tue, Sep 19, 2017 at 11:42 AM James Zeun <james.z...@gmail.com> >>> wrote: >>> >>>> I'll ask around here, I actually might know someone with experience in >>>> this area lol >>>> >>>> My next questions might sound silly, but I'll ask anyway. >>>> What components needs putting on the rex? >>>> What excludes it from being a home built project? >>>> >>>> I'm asking so I can understand it properly in the event I need to >>>> explain it :-) >>>> >>>> >>> >>> Brian documented it here: >>> >>> http://tandy.wiki/Building_a_REX >>> >>> >>> >> >
