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Old 9th Apr 2019, 5:23 pm   #36
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,482
Default Re: MK14 programming interface - MK2

Just had a quick look at JBH's (not JHB as above, sorry about that) link. It appears to use the so called 'sense and react' method in which the would-be-external typist monitors the scanning of the keypad scan drive lines and 'blips' one of the keypad read lines at the exact right moment to simulate a desired key press.

I thought of this method of connection / control right at the beginning as it is potentially the simplest method of all, in terms of hardware, of enabling a microcontroller to 'press' keys - the micro just needs as many i/o pins as there are keypad row and column lines - but it has one unforgivable disadvantage for me: It is not isolated.
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