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[DPRG] serial to parallel shift register with _individually_ tristate outputs

Subject: [DPRG] serial to parallel shift register with _individually_ tristate outputs
From: Quinones, Jose jquinones at ti.com
Date: Mon Oct 10 07:29:59 CDT 2011

Hi Ed,

Seems to me what you need to use is a microcontroller. Seems like overkill, but maybe not so much. Some microcontrollers (I am positive the MSP430's do this) have two registers on their GPIO ports. One of them set the direction, whereas the other set the actual data that will be output. If you program the direction to be an input, the pin in essence becomes Hi Impedance (HIZ).

Of course this would require for some sort of protocol as now you will need to set two registers instead of one. Whatever it is that you are designing may need to be re-designed to take advantage of the new implementation.

Best regards,
 
JIQ

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