Hi Seb, Some comments on the schematic: In the current schematic the 5V and USB-5V are connected, this is not according to spec, see also the datasheet about USB self-powering. Either way, use a jumper selection for the power supply or use some shottky diodes, in addition it might be wise to place a by-pass diode across the 7805, since these devices don't like to be reversed powered.
Why R1? I think you can remove it, since the reset pin is held high via R5/D2 Be sure to put a 100n bypass close to VSS/VDD pins of the PIC, I don't know if C2 is the PIC bypass cap, if so I would draw it closely to the PIC VSS/VDD pins BTW, the 18f14k50 board is working fine Albert On Jul 22, 9:37 pm, Sebastien Lelong <[email protected]> wrote: > Some more thoughts about Jaluino (next guy who talk about math lib, can you > modify the subject plz ?)... > > The connector's layout is very important, as all shields will have to be > compatible, and will reproduce this layout. > For instance, Arduino diecimila has 4 connectors: > > - 2 on on this upper side > - 2 on the bottom side, 1 being reserved to power > > Arduino mega uses a much bigger AVR than Diecimila. They put a double row > connector, on the right side. Still, the four previous connectors are on the > same place. As a consequence, shield for Diecimila can be used with Mega. > > I'd like to reproduce the same. If we build first Jaluino board, 18F2550, it > could have the same connectors as in Arduino (2 on upper side, 2 on bottom > side). Next step is a 18F4550 based board. We could add a single row > connector on the right. In the future, if we decide an even bigger PIC, > we'll be able to double this left connector. > > That said, I still can't produce a PCB, I'm having a lot of trouble placing > parts to avoid vias... Any PCB guru here ? > > PS: as a bonus (...) here's my last schematic, with connectors. > > Cheers, > Seb > > 2009/7/21 Sebastien Lelong <[email protected]> > > > > > > > First try to get a PCB layout gives way too much vias. This is where I > > spend days to get a decent PCB... > > > Seb > > > 2009/7/21 funlw65 <[email protected]>: > > > > On Jul 21, 7:49 pm, Sebastien Lelong <[email protected]> > > > wrote: > > >> I think this assumes the peripheral on the other side (eg. a PC) > > understands > > >> RS232 level between 0 and 5V, instead of -12V and +12V. It's sometime > > the > > >> case, and to be sure, using a MAX232 chip is better. That said, with the > > >> "plug your own serial module" option, you can choose whatever you want. > > This > > >> gives a fourth option, a the cheap side, so we new have: > > > >> - FTDI chip based USB-to-serial adaptor > > >> - 18F14K50 based USB-to-serial adaptor > > >> - MAX232 based, with DB9 connector > > >> - resistor based, with DB9 connector > > >> - (and last option: "my own way to deal with serial") > > > > Ok, not on board, but I thought they can be disabled by jumpers, and > > > can be a fast solution to test the software but yes, is not a good > > > ideea. > > > >> Some more thoughts about the board. Original Arduino Diecimila uses a > > >> Atmega168, a 28-pins chip. > > >> See:http://arduino.cc/en/Main/ArduinoBoardDiecimila. From this, 20 pins > > >> are "exported" through connectors on sides, where 2 pin are dedicated to > > >> RX/TX, thus involved in board's functionality (I mean there aren't > > >> completely free, as they are involved in serial). > > > > I don't know, maybe others have more ideas. First, I looked at > > > ATmega168 pins, to see some similarities at ports level but I think > > > the key is at software level. And is the only level where Pinguino > > > offers Arduino compatibility (and maybe the reason why the author > > > didn't offered a shielded variant). > > > For "reusing" Arduino shields, I think a study must be done. Studying > > > different shields with their software to see how interact with the > > > board. In what manner are used digital pins, etc. ... Because I don't > > > think they take in account very much the particularities of the chip > > > himself (I think the software is hiding the hardware). > > > Maybe is too much work but a shielded board is a must, even if not > > > Arduino compatible. This is jallib team decision, and I hope a good > > > board will increase the number of programmers using jal language > > > (unfortunately, the fact that jal don't have a math library is another > > > obstacle regarding to "mass" adoption - the new comers remain with > > > basic languages and advanced people go to C language). > > > -- > > Sébastien Lelong > >http://www.sirloon.net > >http://sirbot.org > > -- > Sébastien Lelonghttp://www.sirloon.nethttp://sirbot.org > > jaluino_sch2.png > 56KViewDownload- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jallib?hl=en -~----------~----~----~----~------~----~------~--~---
