Fully-detailed instructions for assembly and test of the PIC-EL Kit.
Section 3: TEST POINTS
In general you will be using the component diagrams silkscreened onto the top side of the board as your guide for assembling the board.
A unique feature of this kit is that we designated eleven "test points" that will be very useful for accessing key signals during initial test - supply voltages, encoder signals, I/O line, and more. Additionally, WB8RCR will be be referencing various signals during his Elmer 160 course, asking the student to look at specific signals using a DVM or an oscilloscope. These "built-in test points" thus are valuable in several ways.
The ten test points are:
TP-A = Vpgm (programming voltage), 12V when MODE switch is DOWN in the PGM position
TP-B = +V (supply voltage), whatever your main supply voltage is plugged into the board.
TP-C = Vdd (logic voltage), +5V for the PIC and associated logic
TP-D = GND, ground
TP-F = RF, signal going out (from DDS) or coming in (to be counted), depending on shunt position in HDR2
TP-Ga = ENC-A, encoder A signal, moves in quadrature with the B signal below when encoder is turned
TP-Gb = ENC-B, encoder B signal, moves in quadrature with the A signal above when encoder is turned
TP-H = TONES, normally low signal but has audio freq square wave from 0-to-5V when speaker is sounding
TP-Ia = DIT, normally 5V, goes to zero when dit paddle pressed
TP-Ib = DAH, normally 5V, goes to zero when dah paddle pressed
GND = An extra ground test point is provided at the bottom of the board to serve for convenient in that area.
Test Point general locations ... Looking at the board with "AA0ZZ" in the upper right ... TP's B,C,D,F are in the upper right region; TP's A, Ib, Ga, Gb are in the center of the board; TP-Ia is lower left region; and TP-H is lower center region
Test points are created by bending short (approx 1/2") lengths of clipped component leads into a "U" shape and inserting them into the pc board at each designated position. If you have the typical homebrewers' workbench, you probably have lots of these clipped leads laying around from previous projects. If not, or if you are excessively neat you should see a doctor and immediately get a good dose of HOMEBREWER Magazine.
If you don't have scrap wire available you can get the wire for these test points by clipping off 1/2" lengths of the leads from components you will soon be installing. You won't be needing all the lead lengths on the components anyway. Leave the U-shaped wires slightly elevated as shown in the photo below, then solder them in position. Because these are the first "components" assembled onto the pcb, you may find it easier to solder them from the top side of the board. Installing them as shown will allow easy access to the signal later on with your scope/DVM probe or clip lead.
Be sure to clip off excess lead length from the bottom of the board before continuing on to the next step.
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Page last updated: Feb 8, 2004