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Newzed
09-23-2007, 02:18 AM
I have just finished the design and layout of a new Propeller development board. Here are the features:

5VDC and 3.3VDC regulators.

4-pos female headers for 5VDC and Gnd.

40-pin DIP Propeller.

24LC512 EEPROM using Prop Pins 28 and 29, pullups on SDA and SCL.

PS/2 keyboard connector using Prop Pins 26 and 27.

Prop Plug connector for programming.

DB15 HD VGA connector, using Prop Pins 8-15.

DS1307 8-pin DIP, using Prop Pins 0, 1 and 2. Pullups on SDA and SCL. 4.7K in series with SDA to Prop pin. This device is connected to the Prop with 3 jumpers. Removing the jumpers will disable the DS1307 and leave the Prop pins available for other uses.

TV Connector – installation optional. If installed, removing the 3 jumpers will disable the TV Connector and leave the Prop pins available for other uses.

VGA LED indicator array. Installation optional – uses SMD LEDs and resistors.

MCP3004 ADC – 14-pin DIP, 10-bit, 4-channel – using Prop Pins 20-23. 4-pos female headers for sensor data, sensor ground and sensor voltage(5VDC). Socket must be installed on bottom before the Prop socket is installed. Removal of the chip will disable the ADC circuitry and leave the pins free for other uses. Uses 1 SMD 0805 4.7K resistor and 4 SMD 0805 .1uf caps.

LED power-on indicator.

Four mounting holes.

8-pos female headers for Pins 0-7 and Pins 16-23.

The six 2-pos jumper headers are male pin headers.

This is a complex double-sided board so I can not make it on SuperMill – it must be made by Expresspcb. Since I only want one board, I am looking for someone to take the other two. Cost will be $20.00 plus postage. Prospective buyers must approve the layout, which can be viewed using Expresspcb V6.1. A copy of the layout is attached. Disabling the silkscreen layer will make the circuit more viewable.

Sid

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com (mailto:Module?Newzed@aol.com)

deSilva
09-23-2007, 02:54 AM
Why didn't you connect the DS1307 to Pin 28/29??

Newzed
09-23-2007, 05:03 AM
At desilva's suggestion, I moved the SDA/SCL pins of the 1307 to Pins 28 and 29. I also moved the SQW output of the 1307 to Pin 25 and added a 2-pos female header for Pins 24 and 25. Frees up Pins 0-2, and if you don't install the TV connector, Pins 0-7 will always be available. Rev. A is attached.

Sid

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com (mailto:Module?Newzed@aol.com)

Sparks-R-Fun
09-25-2007, 07:48 AM
Sid,

I think that SuperMill could probably handle the creation of this board if you placed your VGA resistors in a different arrangement. Have faith in Supermill! http://forums.parallax.com/images/smilies/smilewinkgrin.gif It would be an awful amount of work, though.

I have two comments about the board. The first is that you have text in your copper layers. This is ok if that is what you want. However, the placement of some of the copper text items is non-optimal in my opinion. The most troubling is the copper layer “CS” near P22. The “S” *almost* connects P22 with P21. If your board comes with a solder mask, you should be fine as it is. If it comes without a solder mask a stray bit of solder from pad P22 could easily connect it to the copper layer “S” and thus to P21. If you are not aware of that and it occurs, if could be hard to track down.

My second comment concerns that same area. P20 connects to a little square pad on the backside of the board. The matching pad is actually connected to TWO other through-hole pads. The one on the right connects to P19. It is not clear to me if this was intended but the square pad does touch the two through-hole pads on either side of it so they are all connected.

I hope this is helpful.

- Sparks

Newzed
09-25-2007, 08:41 PM
Sparks, thanks for the review. I changed the copper text to silkscreen so that solves that problem.

I made a slight change to the position of the MCP3004, which allowed me to move the square pads at P20. Those pads are for a 4.7K SMD 0805 resistor between the 3004 Dout and the Prop pin.

Revision B is attached. Thanks again.

Sid

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Yesterday is history, tomorrow is a mystery, and today is a gift.

That is why they call it the present.

Don't have VGA?
Newzed@aol.com (mailto:Module?Newzed@aol.com)