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[WP-34S] Cable and flashing options for Mac users
01-23-2015, 11:32 PM (This post was last modified: 01-23-2015 11:39 PM by John Galt.)
Post: #73
RE: [WP-34S] Cable and flashing options for Mac users
(01-23-2015 02:39 PM)jebem Wrote:  The wire with a signal is the TxD from the USB adapter.
The RxD should not show any significant signal in these conditions.

Yes, thank you for that. It disturbs me that it took me so long to determine the problem was a reversed Tx / Rx. Despite the fact I have a scope and know how to use it, "something aint right" was my most erudite conclusion! Live and learn.

The "eureka" moment was when I noticed the scope showing continuous activity. I had been so accustomed to seeing "Unable to connect" from MySamBa that I completely stopped looking at it.

Quote:Did you mean a LED diode connected between the TXD wire candidate and GND to find out which wire is send a data stream?

Yes, something like that. I didn't have your circuit connected at the time, but its LED indicators might have helped me identify the problem. I also gave some thought to including an LED to indicate the calculator's power on / off status... but that might be overkill since pressing the ON button definitely turns it on. If in doubt, press ON. It might not be worth the effort.

Oh and one more thing... have you ever tried supplying calculator power strictly through the programming pads, in other words, batteries removed? I tried working with it that way and wasn't successful. Pressing a key often caused the calculator to turn off.

I surmise the pogo pins I'm using may be inadequate for power. I bought two varieties, both the sharp end and the hemispherical end. I was concerned about excessively scarring the pads with the sharp end, so for testing purposes I'm using the hemispherical end variety at present. The contact area may be sufficient for data, but I suspect it is insufficient for power.
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RE: [WP-34S] Cable and flashing options for Mac users - John Galt - 01-23-2015 11:32 PM

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