9 Jan 2002 hudson   » (Master)

The parts arrived from DigiKey this afternoon and I've spent much of the evening soldering things together.

The good news is that the Atmel AVR Mega163 works on the first try. The bad news is that I screwed up the MAX231 pinouts and the RS-232 line driver is hosed.

Images of the boards:

The Rev 1.1 board will correct this, as well as many other little problems:.

Size issues:
- Thinner headers.  These require grinding to fit
- Larger holes for accelerometer.
- Spacing between AVR and MAX231 is tight if socket is used
for MAX231.
- Spacing with DB9F is very tight.  Requires grinding the DB9F.
- Very small clearances between some of the traces and
through holes.
  These should be larger to make room for sloppy soldering.
- Thinner (0.25) traces are ok for digital lines.  0.30 is
just huge.
- "Cut throughs" between pins only on top-side.  None on
solder side.
- Reduce the number of "expansion holes" and spread out the
components.

Style: - Bi-color LED for power / programming - Status LED for accelerometer/gyros - Opto-isolate digital inputs - Voltage regulator - Remove jumper for Pitch/Roll accelerometer - Make two-axis version usable with one gyro + one accelerometer - Expose all extra lines from gyros and accelerometers - Solder points for IO lines. - Voltage regulator - Divide-by-n chips for tachs - Label servo connectors

Oops: - MAX231 pinout is totally hosed. - Z / Roll accelerometer pins are backwards and must to be used for Pitch/Roll instead. No room for safety pilot PAL that way. - Va, Vr and Vcc links are difficult to reach (but should go away) - If Pitch/Roll accelerometer is used as designed it blocks the voltage regulator spot.

Maybe: - Explore MSP1005-ND from MSI (three axis accelerometer) - Explore Tokin/Murata ceramic gyros - Use two-uart AVR and connect GPS to IMU - Screw-down wire headers for analog/digital inputs

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