开云体育

On Sun, Sep 20, 2020 at 04:39 PM, Raymond Domp Frank wrote:

Would it be safe to treat the DS1742W (3.3 V) as a DS1742 (5 V) for the
copying operation? According to the data sheet, Vcc max is 6 V (not mentioned
separately for either version) and Vin max is specified as Vcc + 0.6 V.
I'm pretty sure I can find a regular(almost) pin-compatible 2 kbyte SRAM from
the supported list and connect that to the TL866II plus, if necessary with a
few wires for pin compatibility.

This is turning into a monologue. I don't mind.

The closest (and much closer than I expected) 3.3 V (DALLAS) NVRAM device that I have found so far is the DS1250W. It's a 512K x 8 device, RAM only, so no RTC.

A simple pin-converter is needed: A 24-pin socket for the DS1742W is placed above a 32-pin socket + header with pins 7 - 28 of the DS1250W corresponding with pins 1 - 24 of the DS1742W.
Pin 29 of the DS1250W is re-routed to pin 21 of the DS1742W and pin 32 of the DS1250W is re- routed to pin 24 of the DS1742W. The original straight-through connections of these two sets are removed, the remaining 22 connections go straight-through.
I haven't yet looked at possible WE/OE/CE (timing) discrepancies in the programmer but I'm confident things will be OK. Only the first 2K of the "DS1250W" will be written.

I'll report back (or possibly, continue this monologue) with results.

Raymond