Sometimes the routing of a PCB can be easier by tweaking the footprints a bit....
Here I didn't need the Q3 and Q4 outputs on a latch so I shrunk down the size of the pads to minimum size and then removed the stop mask on them so they are covered. This makes it easy for me to route a wire between the other pads - something that can't be done on a TSSOP package since the pads are too close together to fit a normal wire between them.
As mentioned in an earlier post I'll try to do one small PCB project every week and then send for PCB's of it every Monday.
Next week I'll do a slightly more advanced project than a simple breakout. I had this idea of making a very complex outline on a PCB and see if Seeedstudio and their fab house would accept it. I'm following the series Supernatural where the protagonists often stay at old motels with a lot of 50-60-70'ies decorations and furniture in them, so I decided to to a wall clock with a retro-inspired design.
The clock will have twelve "arms" each with a RGB PLCC6 (5050) SMD led at the end where hours, minutes and seconds will be represented by a color each.
I'll keep all the parts except for the leds on the backside to give an empty front where I can put some retro-pattern on the silk layer to enhance the retro feeling of it.
This week I have to go up to a 10x10 cm PCB instead of the 5x5 that the PAW designs should use, but I think it will be worth it...
As mentioned in an earlier post I'll try to do one small PCB project every week and then send for PCB's of it every Monday.
#2 was a bit late due to xmas and whatnot, but this project is so much simpler that I'm convinced that I'll be able to submit it Monday.
The PAW 3 is a "super-duper-multiple-dualsided" breakout board. Each PCB currently have 4 copies each of 6 different designs (3 designs on each side). So there's a total of 12 breakout boards with two designs each on a 5x5cm PCB.
Sub-board 1 - A SOIC-16 is sharing the board with a TSSOP-16 on the back. This board also have space to put decoupling caps and LEDs/resistors on it.
Sub-board 2 - A SOIC-8 is shared with a TSSOP-8 on the back.
Sub-board 3 - A SOT-23-6 (small 6 pin device) is shared with 2 pcs of SOT-23 (like a transistor) on the back.
The boards will be done on a 0.8 mm pcb with "cutting grooves" made of 0.25mm wide rectangles of tStop/bStop for easier cutting with a box knife.
Any comments and/or suggestions is welcome before Monday when the order will be sent to Seeed.
It would be nice to be able to have a board with a bunch of the most common USB-capable PIC microcontrollers on it to be able to easily test & debug the Open Source USB stack and bootloaders.
In essence it is a pcb with a single USB connector and a single ISCP and then jumpers to connect them to a particular chip on the board. A reset button and bootloader buttons with status leds might come in handy too. The clock frequency is selectable between 48MHz and 1.5MHz in 15 rather common frequencies.
I did schematics and a pcb design for this a while back, but I never decided what PIC's I should add to the board.
The board supports up to 8 target microcontrollers. I'm not sure if it would be worthwhile to have multiple versions of the same series like 18F24J50/18F25J50/18F26J50 where only the amount of memory differs. It might be good to have all of them on the board(s) to verify that the linker scripts is ok. This would require multiple boards since there are at least 3-4 memory variants of the different product groups.
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Can someone help me decide which PICs I should put on the boards for it to be useful as a testing tool?
As mentioned in an earlier post I'll try to do one small PCB project every week and then send for PCB's of it every Monday.
I've started planning for the second PCB A WEEK project -this time it will be a bit more advanced than the previous project but hopefully it will be finished before the deadline next Sunday.
The basic idea is a digital potentiometer with a 7-segment display that shows the current value. The "potentiometer" is a Rotary Encoder connected to a microcontroller [TBD] that will read the signals from it and convert it to a value that is displayed on the 7-segment displays.
The value will also be sent via i2c/spi/serial/usb [TBD] to the host and possibly also be output as an analogue voltage.
The board also will have six LEDs for status indications.
The board is planned to either be operated in an autonomous mode where the display is updated by the board itself or in a host mode where the host is telling the board what to display.
Just for the fun of it I'll try do design and order a Seeedstudio 5x5 cm PCB every week. I'll do the design and layout during the week and weekend and then submit the order on Monday.
I'm not 100% sure that I'll actually will be able to do this every week, but I'll try as long as possible. Just like Ian does with "A new open source hardware project every month" I'll also count revisions of an existing board as a "new project" if I'm running out of time and/or ideas a week.
Most of these PAW projects will be rather simple and silly things, but since I can for the cost of two coffees at Starbucks get a bunch of PCBs in my mailbox every week I think it will be worth it. I'll most likely send free PCB's to people who ask for it - postage from Malaysia is really cheap.
I'll update this post with a link to a new thread everytime I add a new POW project.
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PAW 1 - NU-Xtal - A tiny 3-pin breakout board with a crystal, caps & resistor NanoUtils@Github 12 Dec - Started design 17 Dec - Sent to Seeedstudio 18 Dec - Seeedstudio "In production" 25 Dec - Seeedstudio "Shipped" 08 Jan - Boards arrived 09 Jan - Built and tested one board
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PAW 2 - DigiPot - A digital "potentiometer" with 7-segment readouts and i2c DigiPot@Github 17 Dec - Started design 27 Dec - Sent to Seeedstudio 28 Dec - Seeedstudio "In production" 04 Jan - Seeedstudio "Shipped" 16 Jan - Boards arrived
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PAW 3 - NU-SockiSop - SuperCombo breakout boards NanoUtils@Github 23 Dec - Started design 31 Dec - Sent to Seeedstudio 04 Jan - Seeedstudio "In production" 08 Jan - Seedstudio "Shipped" 21 Jan - Boards arrived
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PAW 4 - RetroTime - Wall clock with retro-inspired design Retrotime@Github 29 Dec - Started design 7 Jan - Sent to Seeedstudio 8 Jan - Production halted due to error in files 10 Jan - Resent updated gerbers to Seeedstudio 16 Jan - Seedstudio "Shipped" 30 Jan - Boards arrived
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PAW 5 - Oledy - Generic OLED breakout board NanoUtils@Github 7 Jan - Started design 14 Jan - Sent to Seeedstudio 18 Jan - Seedstudio "Shipped" 4 Feb - Boards arrived
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PAW 6 - GolGrid - Expandable 4x4 pixel Conways Game Of Life Golgrid@Github 13 Jan - Started design 21 Jan - Sent to Seeedstudio
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PAW X1 - SuperCombo1 - LCD backpacks, Thru-hole Xtal breakout, USB breakout, SMPS 18 Jan - Started design 19 Jan - Sent to Seeedstudio 28 Jan - Seedstudio "Shipped" 07 Feb - Boards arrived
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PAW 7 - Mainslog/sensor - Mains power grid voltage and frequency logger MainsLog@Gitgub 22 Jan - Re-Started previous design 28 Jan - Sent to Seeedstudio
As mentioned in an earlier post I'll try to do one small PCB project every week and then send for PCB's of it every Monday. This it the first project.
NU-Xtal The NU -part stands for NanoUtils which is a series of really tiny breakout boards that I'll do over time.
This board is a breakout containing a SMD crystal, two caps and a resistor meant to be used in breadboards when building something with an Atmel ATmega or a Microchip PIC that have the two crystal pins next to a GND pin. For instance the atmega328 or pic18f2550.
The board can also be populated with a two pin header at the bottom and then use a short wire from the top of the board to GND if the GND is not adjacent to the xtal pins in your design.
The crystal Digikey Link is a 5x3.2 mm SMD that can be found every now and then for a rather low price - not as low as a standard through-hole HC49 crystal but you have to pay a little extra for the small size. A HC49 is huge in comparison.
Since the board is only 8 x 11 mm I did a step & repeat with 24 copies on a 5x5 cm pcb. Between each copy I have a 0.25mm (~ 10 mil) of tStop & Bstop so I will get a slight groove in the soldermask for easier cutting with a blade. I'll order them as 0.8 mm pcb instead of the standard 1.6mm thickness to make them easier to cut as well.
While waiting for the Kickstarter Bora CPLD trainer to materialize in my mailbox I've started to think a bit about the next stage - having a bit more powerful and feature-rich FPGA trainer board similar to the Bora - maybe without the breadboard. It eats up a lot of expensive pcb area (unless you can mount it hovering a few mm above the board so smd parts can fit under it )
One of the larger and currently popular fpga's that still can be hand soldered seems to be the Spartan-6 LX9 in a TQPF144. In singles it only costs about $17 and seems to have plenty bang for the buck.
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There are already nice development boards out there.
For instance the Atlys™ Spartan-6 FPGA Development Boardhttp://www.digilentinc.com/Products/Det ... Prod=ATLYS with plenty of peripherals and i/o connectors for Ethernet, HDMI and whatnot, but at $349 it's a bit on the pricey size.[attachment=2]
Or the much cheaper Avnet Spartan-6 LX9 MicroBoardhttp://www.em.avnet.com/en-us/design/dr ... Board.aspx - cheap at only $89 but isn't a good trainer board since it lacks user interfaces and most peripherals - except for Ethernet and RAM. [attachment=1]
And then of course the Papilio Prohttp://papilio.cc/index.php?n=Papilio.PapilioPro that will be sold by Seeedstudio for $89, but no user interface and virtually anything else except RAM. [attachment=0]
This is strange.... I though that Seeedstudio only did plated holes in their cheap prototype pcb service. Since non-plated holes needs to be drilled as an extra step after all the other things are done during the manufacturing process I was under the impression that they didn't do that.
The Seeedstudio pcb-test markings can be seen on the edge as well as the telltale additions to the bottom silk layer, so it's definitely a Seeed PCB. But the mounting holes are clearly non-plated...
Today I received the Analog Discovery device sponsored by for the 7400 Logic Competition by Digilent Inc - thank you very much!
It's a dual channel oscilloscope, function generator, power supply and 16 channel logic analyzer combo and it definitely seems like a really nice little debugging tool.
I'll give it a whirl and come back with a report....
