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The Parallax SX48 Prototyping Board is just about the best bargain
around. It has a chip, programming interface, power supply and a high quality prototyping area. However it comes up short in the fact that you
are forced to be soldering your test circuits togther and need to unsolder or even move on to another board to make large changes, and even small
changes take more time.
The SX-Tech Board has everything you would want for protyping board; all of the things that the SX48 board has, it even
has the breadboard, but unfortunately it is dedicated to the SX-28.
However, a little inspection of the SX48 Proto board, and one sees that it could be quite easy to add what is needed to have a ready
prototyping platform.
Here is a parts list to turn a SX48 Proto Board into an "SX Tech Board" for the SX-48.
| Description |
Specification |
Qty |
Mouser Part Number |
| 3M 929 series .100 Shunt |
Red |
1 |
517-951-00 |
| 3M .100” Pin Strip Header |
40 pin 2 Row Gold |
1 |
517-6121TG |
| 3M .100” Pin Strip Header |
40 Pin 1 Row Gold |
1 |
517-6111TG |
| 3M .100 socket header |
36 Pin Solder Tail Tin |
2 |
517-974-01-36 |
| Solderless Breadboard |
Parallax p/n ---> |
1 |
700-00012 |
Specifically the parts need to be cut up and implemented as follows;
- one(1) .100 socket header 1x18 - for RD, RE, RTCC, and MCLR
- one(1) .100 socket header 1x16 - for RC and RB
- one(1) .100 socket headers 1x8 - for RA (could be left out altogther, The SX48 has only
RA0-RA3, and they are already attached to Servo0 to Servo3
- one(1) .100 socket headers 1x8 - for Vss (could be any size up to 1x18)
- one(1) .100 socket header 1x6 - for Vdd
- one(1) .100 socket header 1x3 - for Vin
- one(1) .100 pin header 1x3 - for Vdd vs Vin servo power jumper
- two(2) .100 pin headers 2x3 - for servos 0 through 3
- one shunt for use on the 1x3 pin header for servo power selection
Now, there can be some variations. For example, the 1x8 for Vss could be
shorter or longer there is pleny of room. You could leave out some of the connections.
WIRING and ASSEMBLY there is one bit of tricky wiring. The two pictures to the right depict the
segments. It is simply wiring the servo connector signal lines directly to RA0 through RA3. The wires need to be beneathe the pc board because you
will place the breadboard on top. That is also the reason the four solder joints at the base of the servo connectors must be trimmed fairly flat.
the double sided tape on the bottom of the breadboard will absorbe a little bit of crud from the solder joint.
The rest of the connectors are simply inserted and soldered. Placement should be obvious from the descriptions above and the
pictures to the right.
The order of assembly is almost immaterial, but I would suggest that you solder in the two(2) 2x3 pin headers for the servo
connectors, then do the hand wiring of the servo to RA connections, then the rest of the connectors in any order you wish
KIT of PARTS I can make available a kit parts. You need only supply a few inches of hookup wire.
It's worth the trouble unless you already have reason to make orders to Parallax and Mouser/Digikey. The minimum shipping fees for small order
from the two would more than double the price. My kit would include a Parallax breadboard and all parts pre-cut on a bandsaw with a fine blade.
If you are interested, see below.
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