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|D Type||10 Pin Header||Label||
|1||1||RQONOFF||0v - wake; open/+v - sleep||Controlled by sensor driver modules|
|2||3||Rx1||RS232 Rx for general purpose use||For ad-hoc connection of RS232 devices without driver modules|
|3||5||Tx1||RS232 Tx for general purpose use||(as 2 above)|
|4||7||+V||Unregulated +V supply - 7 to 17v||Regulated supplies are generated from this line using voltage convertors/regulators as appropriate at each device. Devices are switched on/off by local controllers.|
|6||2||Gnd/Spare||Ground for 'mirror' RS232 working with Rx3/Tx3||See also 8 & 9|
|7||4||Tx3||Serial Tx connection to sensor modules||Sends requests for data to all sensors - $S"%s"xxx..x (%s: sensor name xx..x: data threshold) 4800 baud (3.3V CMOS?)|
|8||6||Tx2||RS232 Rx for connection to Handheld/Palmtop display||Generally used as an output port - N.B.This connection will function as a conventional RS232 port when a conventional RS232 connector e.g.'D' type is connected the 'wrong' way round onto the bus (but make sure the unused pins are cut/disconnected).|
|9||8||Rx2||RS232 Tx for connection to Handheld/Palmtop display||As 8 above|
|NC||10||Rx3||Serial Rx connection to sensor modules||Receives data sent from sensor modules - $R"%s"xxx..x 4800 baud TTL (3.3V CMOS?)(as 7 above)|
OK - it's really 10 wire - but two are connected to ground! Inspired by Spinal Tap!!
Conventional 10pin IDC headers are capable of being connected to two ribbon cables simultaneously and hence can provide 'Y' junctions on the bus n.b. substantial clamping pressure is required to ensure proper contact is made. .
We have tested standard 'grey' ribbon cable - it has a resistance of 0.16 ohms per metre. At 1.5 amps the voltage drop across one metre is 0.25v. A current of 4 Amps was successfully passed through it without catastrophic failure (it did warm up a bit though!). We conclude that it is suitable for use on our wearable with the Bitsy and multiple sensors. However the use of head mounted, or other, displays will probably require dedicated power supplies.
In addition USB and audio in/out are available. Relevant devices can
be connected directly to the processor board.