Technical guide
Reference material on Touch Memory and 1-Wire identification — compatibility, family codes, common questions and how to source these parts properly.
DS1990A vs TM1990A vs RW1990: what is the difference?
Compare read-only DS1990A and TM1990A with rewritable RW1990: ID type, writer support, sample checks and ordering terms for TM1990A-F5 and RW1990.
iButton / 1-Wire family code reference table
Use family codes as a first check of a 1-Wire ROM format, then verify the exact part, documentation and device behaviour. A printed ID alone cannot identify a manufacturer or prove compatibility.
Touch Memory & iButton FAQ
Straight answers to the questions buyers and installers actually ask about iButton, DS1990A, TM keys, rewritable blanks, readers, compatibility, lifetime and ordering.
How to wire a Touch Memory reader (TM+, TM−, LED)
Check the supplied reader diagram for data, ground and LED connections. Wire colours and pin numbers vary by device; confirm controller requirements before connecting a Touch Memory reader.
DS1990A reference: 1-Wire timing and electrical checks
Selected timing and electrical reference values for the original DS1990A, from Analog Devices. These are not DS1990AA, TM1990A-F5 or RW1990 specifications; confirm each supplied version separately.
OEM & ODM options: colours, laser marking, ROM ranges, packaging
Prepare an OEM request for housing colour, marking, ID management, assembly and packaging. Feasibility, costs, MOQ and lead time need confirmation for the quoted version.
Sauna & locker lock: how the card hierarchy actually works
Master, pass, user, service and clear cards — what each one can and cannot do, why the master card deliberately cannot open a door, how to switch between single-card and double-card mode, and what to do when a card is lost.
How to source Touch Memory keys: a buyer’s checklist
What to verify before placing a volume order for iButton or TM keys — chip authenticity, read reliability, packaging, custom ROM ranges, MOQ, lead time and the questions worth asking any supplier.
iButton key not reading? A 10-cause troubleshooting ladder
A key that reads nowhere, reads sometimes, or reads on one door but not another — each pattern has different causes. A test-first ladder covering dirty contacts, wrong blank formats, reversed wiring, ground loops, worn readers and dead keys.
Choosing an intercom blank: model and format checks
Use Vizit, Cyfral, Metakom and Eltis names as starting points, then confirm the panel, firmware, credential format and writer support. Compare candidate blanks and validate samples before buying.
How Touch Memory key copying works — process and equipment
What actually happens when a TM key is duplicated: reading the 64-bit ROM, choosing the right rewritable blank, the write routine, and verification — plus which copier fits a shop counter, a mixed estate or field batch work.
Need these parts in volume?
Send the model, quantity and delivery country. Pricing, sample terms, availability and lead time are confirmed for your request.
Request a quote