Rev. E - first article

J. Dunmire
February 6, 2003

Notes on building the first article

The first version of the ECPE-5 PIC Project Board was assembled on Feb. 5th, 2003 using those parts we could find at UOP. We (Dr. Turpin, Dr. Dunmire, and I) did get a unit to function, but there were some problems. Pictures of the PCB, the assembled prototype, and MPEG clips of the the prototype in operation are shown below.

Problems found:

The holes for J6 are too small, they should be the same size as the holes for J3 and J5.
Too much space is allocated for the switches (the switches are only 6mm x 6mm).
A right-angle 9-pin connector can not be installed (J1) because it would face into the board. While the board was not designed specifically for a right-angle connector, rotating the hole pattern 180° would allow that option.
The rectifier (D6) is wired wrong.
The row sequence for the large 5x7 LED dot matrix display is wrong. See the video clip.
Rows are ordered left-to-right for the large 5x7 LED dot matrix display and right-to-left for the two small 5x7 LED dot matrix displays. They should be the same so that programs do not need to be modified to support the two different displays.

Other notes:

The power supply section was not assembled and tested because correcting D5 would have required several cuts and jumps.
Electrolytic capacitors were used for C1-C4 because they were available when we started the assembly. (The correct capacitors arrived later in the day.)
A crystal (X1) and two capacitors (C7 and C8) were used for the CPU oscillator because the appropriate ceramic resonator was not available at assembly time.
The dot matrix LEDs are more efficient than expected so the current limiting resistors (R10-R19) can be increased to 330 ohms.
Use the extra space that will be gained, when the switch sizes are corrected, for a serial DAC and/or a temperature sensor. Either device would allow for experiments with the I2C serial interface.
The 8-pin headers specified in the parts list are round rather than square pins. That should not be a problem, but was un-expected.
The discrete LEDs (D1-D4) specified in the parts list have a long spacer. A flush mount version would be better.

PCB

These pictures show the PCB before assembly. Two prototype PCBs were fabricated by PCB123.

Component side. Actual size = 4.1 x 2.5 inches.
(Click on the image for a larger view.)

Solder side.
(Click on the image for a larger view.)

Assembled Prototype

The prototype was tested with the ECPE-5 +5v Linear Power Supply (the board on the left in each picture).

Assembled with two small 5x7 dot-matrix LED displays.

Assembled with one large 5x7 dot-matrix LED display.

Video

The following links lead to some MPEG clips of the prototype in action.

The four LEDs on the CPU section in action.

Column sequence on the two small 5x7 LED Displays.

Column sequence on the large 5x7 LED Display (it's wrong!).

$Date: 2008-10-21 19:17:35 $
$Source: /home/cvsroot/projectsTop/picProjectBoard/RevE_Build.html,v $ Contact me by email: jedunmire at gmail.com

	Component side. Actual size = 4.1 x 2.5 inches. (Click on the image for a larger view.)
	Solder side. (Click on the image for a larger view.)

	Assembled with two small 5x7 dot-matrix LED displays.
	Assembled with one large 5x7 dot-matrix LED display.