Saturday, July 4, 2009

Wise Clock PCB goes SMD & TH

Finally I succeeded in designing the Wise Clock PCB to accomodate both SMDs and through hole components. Well, not for all ICs, just two of them: DS1307 and 24LC256. Quite a challenge, since full overlapping is not possible (due to the different gauge between pins, although the widths are identical).

To recap, Wise Clock is an Arduino clone, fully compatible with the existing Arduino shields. Wise Clock offers an RTC (DS1307) with a backup battery, and an EEPROM (24LC256), both connected on I2C pins (analog 4 and 5) of Arduino. Wise Clock is powered by a regulated 5V power supply (2 pin molex connector) and connects to the serial port through the FTDI connector (lower right corner in the image below).

A new feature of the latest board (version 1.2) is the optional connection with an XBee adapter from adafruit. This is possible through the 10 pin female header at the bottom of the board. The XBee adapter also supplies the 3.3V to the Arduino "3V3" expansion pin. There is also circuitry on the board that allows to remotely reset of the microcontroller and to upload sketches (adapted from the adafruit XBee tutorial).

Here is how the board looks like. The EEPROM and DS1307 are placed in the upper right corner (the SMDs cover pins 2 and 3 of the TH package).

Now I could solder on the board either the SMD (cheaper) or the through hole. And since they somehow overlap, there is no chance to mistakenly solder both SMD and TH of the same component.

Next steps are to order the board and actually build and test it.

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