TDA8005 Datasheet, PDF (16/32 Pages) NXP Semiconductors – Low-power smart card coupler

Philips Semiconductors
Low-power smart card coupler
Product specification
TDA8005
If no error has occurred, the UART sets the bit US0
(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 the bits BUFFER EMPTY
and US4 (parity error during transmission) 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 the 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. The bit T/R must be
reset to enable the reception of the following characters.
When the session is completed, the microcontroller
re-initializes the whole UART by resetting the bit RESET
ISO UART.
handbook, full pagewidth
T/R ↑
SET TRANSMIT ENABLE
transmit register selected
CONVERT, CALCULATE PARITY
AND LOAD IN TRANSMIT
(1)
SHIFT REGISTER
SHIFT EVERY ETU IF TRANSMIT
ENABLE IS SET
10th bit shifted
SET I/O BUFFER IN
RECEPTION AT 10 ETU
SAMPLE I/O AT 11 ETU
parity error
SET BIT TRANSMISSION PARITY
ERROR AND BUFFER EMPTY
AT 11 ETU
SET BIT BUFFER EMPTY
(2)
AT 11 ETU
LCT = 1
RESET TRANSMIT PART AT 11 ETU
FORCE RECEPTION MODE
RESET TRANSMIT PART AND
ENABLE TRANSMIT AT 12 ETU
T/R = 0
RESET TRANSMIT PART AND
ENABLE TRANSMIT AT 13 ETU
MBH637
(1) The transmit register may be loaded just after reading from the status register.
(2) The software must reset the last character but before completion of the first received character.
Fig.7 ISO UART transmission flow chart.
1996 Sep 25
16