TDA8005A Datasheet, PDF (16/36 Pages) NXP Semiconductors – Low-power 3 V/5 V smart card coupler

Philips Semiconductors
Low-power (3 V/5 V) smart card coupler
Preliminary specification
TDA8005A
When the controller needs to transmit data to the card, it
first sets bit UC3 in the UART configuration register which
configures the UART in the transmission mode. As soon
as a character has been written in the UART transmit
register, the UART makes the conversion, calculates the
parity and starts the transmission on the rising edge of
ENABLE. When the character has been transmitted, it
surveys the I/O line at 11 ETU in order to know if an error
has been detected by the card.
If no error has occurred, the UART sets bit US0 (UART
transmit buffer empty) in the status register and waits for
the next character. If the next character has been written
before 12 ETU, the transmission will start at 12 ETU. If it
was written after 12 ETU it will start on the rising edge of
ENABLE.
If an error has occurred, it sets bits US0 and US4 (parity
error detected during transmission of a character) which
warns the microcontroller to rewrite the previous character
in the UART transmit register.
If the character has been rewritten before 13 ETU, the
transmission will start at 13 ETU. If it has been written after
13 ETU it will start on the rising edge of ENABLE.
When the transmission is completed, the microcontroller
may set bit LCT (Last Character to Transmit) so that the
UART will force the reception mode into ready to get the
reply from the card at 12 ETU. This bit must be reset
before the end of the first reception. Bit UC3
(TRANSMIT/RECEIVE) must be reset to enable the
reception of the characters to follow.
When the session is completed, the microcontroller
re-initializes the whole UART by resetting bit UC0 (ISO
UART RESET).
1998 Mar 20
16