Comments on: LED Clock: It’s the Voltage, Man (DS1302) http://www.neufeld.newton.ks.us/electronics/?p=104 Sun, 08 Dec 2024 17:19:24 -0600 hourly 1 http://wordpress.org/?v=3.1.3 By: Keith Neufeld http://www.neufeld.newton.ks.us/electronics/?p=104&cpage=1#comment-26403 Keith Neufeld Thu, 14 Oct 2010 19:07:11 +0000 http://www.neufeld.newton.ks.us/electronics/?p=104#comment-26403 cde, thanks for the note! I welcome good ideas, even four years later, because it's never too late to learn. In this case, however, it was a 5V PIC (and actually running at 5V), so I don't think it was a problem with logic-level interfacing on the PIC side. cde, thanks for the note! I welcome good ideas, even four years later, because it’s never too late to learn.

In this case, however, it was a 5V PIC (and actually running at 5V), so I don’t think it was a problem with logic-level interfacing on the PIC side.

]]> By: cde http://www.neufeld.newton.ks.us/electronics/?p=104&cpage=1#comment-26372 cde Sat, 09 Oct 2010 16:51:34 +0000 http://www.neufeld.newton.ks.us/electronics/?p=104#comment-26372 I know this is 4 years too late, but just wanted to mention that the write failures could be due to input voltage tolerances on the data pins, in regards to supply voltage. If, when v+ for the rtc is at 5, data input registers a high at 0.7*V+ and higher, which is 3.5v, and the pic is signaling high at its 3 or 3.3v level, and that is above the registering a low voltage, the ic would be getting a floating voltage issue. Same thing the other way around, with the rtc signaling at its typical volatge level for high, and that being above the pic's input voltage. I know this is 4 years too late, but just wanted to mention that the write failures could be due to input voltage tolerances on the data pins, in regards to supply voltage.

If, when v+ for the rtc is at 5, data input registers a high at 0.7*V+ and higher, which is 3.5v, and the pic is signaling high at its 3 or 3.3v level, and that is above the registering a low voltage, the ic would be getting a floating voltage issue.

Same thing the other way around, with the rtc signaling at its typical volatge level for high, and that being above the pic’s input voltage.

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