User manual

ECE 477 Final Report Spring 2004
For the remote device, the LCD module dictates the level of the battery supply. A 6V
power supply is easily made using a number of combinations of batteries. It was decided to use
4 AA alkaline batteries. AA alkaline batteries are 1.5V compared to the 1.2V lithium ion and
nickel metal hydride batteries. This supply can be regulated to 5V and 3.3V levels using
National Semiconductor LP2992 low drop-out voltage converters [8]. The low power
dissipation of our remote device design minimizes strain and prolongs battery life. The base
computer will be powered by a 5V wall-wart and regulated to 3.3V.
The base computer is quite similar to the remote device setup. The most significant
difference is in the need to interface with a PC through a serial port. The remote device includes
a DB9 connector that uses the Maxim MAX3222 RS232 logic level translator [6] to translate the
signal from the serial port into TTL logic for the RF transceiver. The 3222 is a low-cost, one-
chip solution that works at 3.3V. No logic translation is needed between the translator and the
RF device.
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