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On Thu, 6 Oct 1994 uunet!VNET.IBM.COM!wa3pwx@sc*.uu* wrote: > Radio Shack carries the 9v Ultralife lithium battery for $6.99. > > Speaking of the Phoenix, does anyone know the details of the data interface > for downloading info to the PC? I assume it's a serial data stream picked > up by a phototransistor from the ceiling indicator LED. What I don't know > is what is the baud rate and data format? Also, how does one initiate the > transfer or does it just do it automatically during the power-up > initialization? > > Thanks for any info.....Al Secor wa3pwx@vn*.ib*.co* As I recall, it is standard async, 2400,8,N,1. The format of the dump is a hex dump with addresses on the left, and data on the right. Each line ends with CR/LF. There is a control character at the beginning, and another one at the end. The interpretation of the dump is quite an exercise. The data transfer is initiated by powering the computer up, letting it initialize, and then quickly disconnecting and reconnecting the battery. This causes the computer to spew its guts out by oscillating the LED. On the Ocra Delphis, one could read either the LED with a phototransistor, or, less reliably, the voltage drop from the battery as the signal was turned on and off. On the Phoenix, claims are that the circuitry is better, so you have to read the phototransistor. I was never able to come up with a circuit that would work with a common (Radio Shack) phototransistor. I was able to use a commercial part (it has been a while) which had better sensitivity in the visible spectrum (phototransistors mostly work in the infrared. The led broadcasts in the visible) to build a simple 1 transistor circuit which was controlled by the LED, and powered by the RS232. This was published on the net (rec.scuba). (I should clarify - I didn't design this circuit - I just built it.) I did design and build a circuit that used a voltage comparator against the battery voltage, but it required hand adjustment with an oscilliscope to get it to read, so I don't think I ever published it. I asked a bunch of EE folks about building a circuit that would automatically center on the voltage drop, and not require tuning, but none of them could come up with anything offhand. A lot of this discussion could possibly be ferreted out of the rec.scuba archives. It happened several years ago - shortly after the delphi was introduced. Nick Simicich - njs%scifi.uucp@uu*.uu*.ne* - njs@bc*.vn*.ib*.co*
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