How do you design these days?
in [Design]
|
From: Michael A. Terrell on 1 Jan 2010 18:12 Jim Thompson wrote: > > On Fri, 01 Jan 2010 16:17:30 -0500, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > > >On 1/1/2010 3:56 PM, Joerg wrote: > >> krw wrote: > > > >>> Why are pin numbers an issue? You never probe from the backside of a > >>> board? The spatial transform is pretty ingrained in me and I spent a > >>> decade doing processor design (no PCB stuff). > >> > >> > >> Until one fine day you have one of those Supertex high voltage chips. > >> Some weirdness happens on the prototype boards, must be a software > >> issue. It's always software. Has to be. Hmm, let's see how that looks on > >> the old breadboard. Grab probe, lemmee see, serial data out was, uhm, > >> umpteenth pin from upper left ... POP ... *PHOOMP* > >> > > > >How dull your life would be without fireworks, though. ;) > > > >Cheers > > > >Phil Hobbs > > Indeed! I haven't had a "fireworks" event since ~1980. I wonder if Joerg demands at least one fire extinguisher in all his design contracts? :) -- Greed is the root of all eBay.
From: Michael A. Terrell on 1 Jan 2010 18:15 John Larkin wrote: > > One of these days I'm going to have a board house gold-plate a bunch > of FR4 scraps. Boy would you guys have breadboard envy! Or use the corners that would be wasted for small perfboards. You could end up with a nice selection over time. :) -- Greed is the root of all eBay.
From: Michael A. Terrell on 1 Jan 2010 18:16 Joerg wrote: > > Wish we had such flea markets up here near Sacramento. But it's mostly a > city of bureaucrats :-( Where they buy & sell old politicians? ;-) -- Greed is the root of all eBay.
From: Michael A. Terrell on 1 Jan 2010 18:18 Fred Abse wrote: > > On Thu, 31 Dec 2009 17:29:44 -0600, krw wrote: > > > "Whenever more than one person is involved in a screwup, blame will > > never be placed." > > Managers fix blame. Engineers fix the problem. Then the managers create new problems. :( -- Greed is the root of all eBay.
From: Jan Panteltje on 1 Jan 2010 18:20
On a sunny day (Fri, 01 Jan 2010 10:43:15 -0800) it happened John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in <pmesj5tg8ktljbuiap3bieol9955dajvhl(a)4ax.com>: >Incidentally, I recommend this gadget > >http://www.rs-485.com/daqitemw.asp?record=95 Oh, now I see, you did not do the top board, it is theirs? >for projects like this. It works as advertised and is easy to use. I >expected to have to do some signal averaging on my temperature >acquisition, but it's dead stable without. Of course, the braid+foil >shielded RG174 runs to the RTDs may have helped. >> >>The digital inputs / output are driven by a PCF8574 (bidirectional i2c I/O expander), >>and the inputs by a PCF8591, a 4 channel i2c 8 bit AD + DA converter. >>The i2c hands on 3 pins of the PC par port. >>In the original design there was a local LCD driven by 2 PCF8574 remotely too. >>No RS232 then. >>This has been working since the eighties without problems, >>but I accidently killed the LCD (main wire dropped on a data line), and took it out. > >I got 100% spares for this project, and a bunch of bare boards for >free, so it should last. Yes, no problem with spares, have a new LCD in the drawer, but since it moved from 100% embedded (8052 AH) to the PC it no longer needed it's own LCD display anyways. I just realized I still have that 8052 box, it has a 8049 EPROM programmer board too, Now that is a nice small BASIC programmable Harvard architecture system :-) >Absolutely *everything* about this project worked as expected, first >time. Except the software, of course. The hardware I planned and >checked. The software, I just sat down and started typing. I had a >little trouble shelling out to the FTP stuff while running the >realtime part, which I fixed by writing a separate program to do the >ftp transfers. > >The hard part was pulling the wires. Yes, that requires muscle :-) >>The original soft was also in BASIC, MCS BASIC on a 8052 ! >>Anybody remember MCS BASIC? >>Then rewrote it in C, and ported to CP/M. >>That C ported to DR DOS. >>That DOS C ported to Linux. >>And it still works today:-) >>Recently I added a temp PIC temp sensor via an USB to RS232 adaptor, >> http://panteltje.com/panteltje/pic/temp_pic/index.html >>if that sensor fails (is not connected) the software detects it, and switches back to the LM135. >>Interesting to write the soft that detects all the possible USB errors, finally >>had to have it check the data format the temp_pic sends, to make sure >>USB enumeration had not caused some other sensor to be read.... > >Yeah, I had to consider all sorts of failure modes so that the heat >wouldn't stay on full-blast for weeks. > >>i2c was and is, a lot simpler, not sensitive to random delays due to multi-tasking OS either. >>temp_pic sensor is cool, had it in the fridge to -18, and in boiling water to 100 C. >> > >The semiconductor sensors usually aren't very accurate. The RTDs are >fantastic. I can't imagine how they calibrate them in production. > >I considered the Z-wave home automation stuff, but their temp sensors >only go down to 40F and are of unknown accuracy. Plus, I wouldn't have >long-term maintainability, and remote access could be a problem. And I >wouldn't have had a project for this week. > >Here it is installed in the ski-boot closet. All I have to do is wire >up the furnace control and clean things up. > >ftp://jjlarkin.lmi.net/Auto_wired.jpg I have a similar problem with wall-warts... we need some better solution for that. That thing has a cover to protect it I hope? Here is my old 8052AH BASIC computer that originally controlled everything: ftp://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_img_1725.jpg You can see the 8052AH chip with 'BASIC' written on it just visible next to the flat cable on the right: ftp://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_inside_img_1727.jpg The side slides out, you can then slide in this programmer board for the 8049 EPROM version: ftp://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_8049_programmer_board_img_1731.jpg It has collected a lot of dust, not used for so many years. On the rear the DIN connector is i2c (external) to all the I/O, there are 2 RS232 connectors, a power connector, and some extra I/O directly from the 8052 AH pins. ftp://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_rear_img_1728.jpg I wonder if the NICAD (the big yellow thing) is dead after 25 years of no use.... It is for SRAM backup. You can also see the pot core for the EPROM programmer voltage generator. The whole thing runs on a 12 V DC adaptor. May even try it some day, it should just work with the current system, it still uses the DIN 5 pole to connect to a cable that connects to the PC. Computers have something eternal... ftp://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_rear_img_1728.jpg >Needs more tie-wraps. > >John > > > |