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TI/Stellarus Definition of "Weak"

No way are those weak pull ups 110k!!!

I just put a pull up on the JTAG reset pin of a TI LM3S2533, because my JTAG wasn't working and my 10M-ohm input VOM was reading the pin as being as low as low could be. I'm down to using #32 magnet wire as mod wire, to fit the pins on the processor, and if I have to change that sucker it's going to be a pain and a half.

The data sheet says 50k to 110k. Lessee. Ohms law. Fluke 77 has 10M- ohm input impedance, a "weak pull up" resistor of 110k-ohm should make it read 33mV below 3.3V, right? So when I read 0.15V, then either the laws of physics are being violated, my meter breaks only when I measure those voltages, or the stinking data sheet lies!!!

Grr.

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www.wescottdesign.com
Reply to
Tim Wescott
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You need to enable the pullups on some ARMs, also they are sometimes not available on analog or other "special" pins.

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John Devereux
Reply to
John Devereux

Are you sure the weak pullup hasn't been disabled by accident? (doesn't it also have weak pulldowns available too - maybe a typo?)

Regards, Martin Brown

Reply to
Martin Brown

They're supposed to be there coming out of reset (particularly on this pin), and I'm explicitly setting them later.

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www.wescottdesign.com
Reply to
Tim Wescott

Un bel giorno Tim Wescott digitò:

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[...] 1.1 JTAG pins do not have internal pull-ups enabled at power-on reset [...] 
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Fletto i muscoli e sono nel vuoto.
Reply to
dalai lamah

Or your chip's broken or somebody programmed the pin as an output and it's outputting a low.

Hope This Helps! Rich

Reply to
Rich Grise

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