CNI widgets: Difference between revisions
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imported>Bobd Created page with "= Serial port scan trigger device = = GE physiological data monitor =" |
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= GE physiological data monitor = | = GE physiological data monitor = | ||
== Circuit tidbits == | |||
=== RS232 level converter === | |||
We need a little circuit to take the scanner data stream (-12v to +12v) and allow it to be safely ready by our 5v microprocessor. We just took the Tx part of [http://picprojects.org.uk/projects/simpleSIO/ssio.htm this simple RS232 level converter]. We used a [http://en.wikipedia.org/wiki/2N3904 2N3904 transistor] with emitter to ground, collector to the UART Rx pin on the microcontroller with a 10k pull-up resistor to the 5v line, and the base connected to the Tx line coming from the scanner via a 4.7K resistor, with a 4.7k pull-down to ground. | |||
Revision as of 18:28, 18 May 2011
Serial port scan trigger device
GE physiological data monitor
Circuit tidbits
RS232 level converter
We need a little circuit to take the scanner data stream (-12v to +12v) and allow it to be safely ready by our 5v microprocessor. We just took the Tx part of this simple RS232 level converter. We used a 2N3904 transistor with emitter to ground, collector to the UART Rx pin on the microcontroller with a 10k pull-up resistor to the 5v line, and the base connected to the Tx line coming from the scanner via a 4.7K resistor, with a 4.7k pull-down to ground.