Propeller Board in ExpressPCB
Mike Cook
Posts: 829
Anyone working on a board layout in ExpressPCB and willing to share your design? Did not want to 're-create the wheel' if something is already in the works!
When I get some time, in the next few weeks, I'm going to attempt to do a general purpose board, kind of like the SX48/52 Proto Board, using ExpressPCB's format of 2.5" x 3.8" probably will have the following:
1. Power Input 2.1 coaxial jack or .2" two position screw header
2. Three way power switch (OFF, 3.3 & 5 ONLY, 3.3, 5, VIN)
3. 3.3VDC power supply (switcher would be nice)
4. 5VDC power supply (switcher would be nice)
5. Power LED for each supply (VIN, 3.3, & 5)
6. P8X32A-Q44 (may do DIP-40 incase I need to 'rob the processor' for another project)
7. xtal socket
8. EEPROM, with 4.7k pull-ups and extend to a 4 or 5 position header for external I2C bus
9. Reset switch
10. Still deciding if I want to use, discrete, MAX-232, or USB2SER. Needed for programming and would also like to use for stand alone operation (RS-232) may actually want two RS-232 type serial ports. This needs more thought.
11. Bring out all I/O to some type of header
12. Four mounting holes, one in each corner.
What I'm shooting for is a standard size, inexpensive board that can have stackable expansion modules, to be used for prototyping or single projects.
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Mike
Comments
Regarding #9
Mouser has the MAX3232 on back order for 5 weeks.
I just went back to your transistor design because the MAX232 is a 5volt TTL/CMOS logic that must be adapted to the 3.3V I/O.
I was quite tempted to just plug one in and see what would happen, but with a $25chip I haven't got the guts to do so.
I would love to see how to use a MAX232 as they may remain more available. I guess the reset would by-pass it completely if you want to use all four. That would not only allow two duplex RS-232 ports; it would allow one duplex RS-232 with hardware handshake if the software supported such.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Well I'm not encouraging blowing up a chip, but from what I'm reading on the forums, I would not hesitate to try the MAX-232 and use separate power supplies for each chip with a shared ground. I'll know more when my four Propellers get here!
I built my 'Home Brew Demo Board' to use the USB2SER, discrete programmer, and have a MAX-232 board mounted for just RS-232. Right now in the MAX-232 board, I've got the 5 volt chip in the socket, but also have a few Sipex versions of the MAX-3232 chips on hand.
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Mike
It certainly would be nice if they were completely interchangible, but I think one prefers 1mfd and the other 0.1mfd capacitors. But from what I read all will work with 0.1mfd. Am I correct?
Will the MAX-3232 operate at 5volts or does a jumper have to be in place?
As it stands, I ordered 20 MAX3232s because the world seems to be going to 3.3volts and the DIPs are getting harder to find. Fortunately with sockets it doesn't matter about RoHS compliant because you plug them in rather than solder.
Seems everything might be RoHS compliant within a year or so as manufacturers really don't care for twin inventories [noparse][[/noparse]their accountants yell at them].
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
C:\Program Files\ExpressPCB\SchComponents_Custom
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Jon Williams
Applications Engineer, Parallax
Thanks for the custom components! That saves several hours right there (the way I work).
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Mike
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Just tossing my two bits worth into the bit bucket
KK
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I'm looking for the LIB, otherwise I will make it !!
thanks
I started making this for the same reasons that you want to make one. I basically used the info from the forums. I havnt started to create the board but I could post that as well in a day or two. Plus Im not sure what other things I want to include on this as well.
It's a start.
Paul
Post Edited (The-electronics-guy) : 5/3/2006 8:31:23 AM GMT