Having now downloaded the dumb reader schematic via the URL in Joe Phillips' message, I can see why they did it that way. This is a mid-90s design for home constructors, which (a) has low component cost, and (b) has options which are either designed in to allow memory cards to be used (card clocking via the RS232 DTR line) or are no longer needed for cards complying with the 1997 edition of ISO 7816 part 3 (e.g. active high reset is no longer used in new card designs). It uses an open collector driver (Q2) for data transmit to the card, which is the proper way to do it. However, its use of the card coupler's 'card detect' switch to apply Vcc to the card means that the card coupler must have a high quality switch (some have just a carbon pill switch, which will not carry the card current).
Peter T Bristol UK ----- Original Message ----- From: "Jim Rees" <[EMAIL PROTECTED]> To: "Smart Muscleheads" <[EMAIL PROTECTED]> Sent: Friday, February 22, 2002 7:16 PM Subject: Re: MUSCLE Dumb Serial readers - Driver request > The dumbmouse is needlessly complicated. All those discrete parts can be > replace by a max232. An added benefit is that the device will then conform > to rs232, which can be important in some applications. > *************************************************************** > Unix Smart Card Developers - M.U.S.C.L.E. > (Movement for the Use of Smart Cards in a Linux Environment) > http://www.linuxnet.com/ > To unsubscribe send an email to [EMAIL PROTECTED] with > unsubscribe sclinux > *************************************************************** > > *************************************************************** Unix Smart Card Developers - M.U.S.C.L.E. (Movement for the Use of Smart Cards in a Linux Environment) http://www.linuxnet.com/ To unsubscribe send an email to [EMAIL PROTECTED] with unsubscribe sclinux ***************************************************************
