TDA8029 Datasheet, PDF (20/58 Pages) NXP Semiconductors – Low power single card reader

Philips Semiconductors
Low power single card reader
Product specification
TDA8029
address. Two special function registers are used to define
the slave addresses, SADDR, and the address mask,
SADEN. SADEN is used to define which bits in the SADDR
are to be used and which bits are ‘don’t cares’. The
SADEN mask can be logically AND-ed with the SADDR to
create the given address which the master will use for
addressing each of the slaves. Use of the given address
allows multiple slaves to be recognized while excluding
others. The following examples will help to show the
versatility of this scheme.
Table 15 Slave 0
REGISTER
SADDR
SADEN
Given
VALUE (BINARY)
1100 0000
1111 1101
1100 00X0
Table 16 Slave 1
REGISTER
SADDR
SADEN
Given
VALUE (BINARY)
1100 0000
1111 1110
1100 000X
In the above example SADDR is the same and the SADEN
data is used to differentiate between the two slaves.
Slave 0 requires that bit 0 = 0 and ignores bit 1. Slave 1
requires that bit 1 = 0 and bit 0 is ignored. A unique
address for slave 0 would be 1100 0010 since slave 1
requires bit 1 = 0. A unique address for slave 1 would be
1100 0001 since bit 0 = 1 will exclude slave 0. Both slaves
can be selected at the same time by an address which has
bit 0 = 0 (for slave 0) and bit 1 = 0 (for slave 1). Thus, both
could be addressed with 1100 0000.
In a more complex system the following could be used to
select slaves 1 and 2 while excluding slave 0.
Table 18 Slave 1
REGISTER
SADDR
SADEN
Given
Table 19 Slave 2
REGISTER
SADDR
SADEN
Given
VALUE (BINARY)
1110 0000
1111 1010
1110 0X0X
VALUE (BINARY)
1110 0000
1111 1100
1110 00XX
In the above example the differentiation among the
3 slaves is in the lower 3 address bits. Slave 0 requires
that bit 0 = 0 and it can be uniquely addressed by
1110 0110. Slave 1 requires that bit 1 = 0 and it can be
uniquely addressed by 1110 and 0101. Slave 2 requires
that bit 2 = 0 and its unique address is 1110 0011.
To select slaves 0 and 1 and exclude slave 2 use address
1110 0100, since it is necessary to make bit 2 = 1 to
exclude slave 2.
The broadcast address for each slave is created by taking
the logical OR of SADDR and SADEN. Zeros in this result
are treated as don’t cares. In most cases, interpreting the
don’t cares as ones, the broadcast address will be FFh.
Upon reset SADDR (SFR address 0A9h) and SADEN
(SFR address 0B9h) are leaded with 0s. This produces a
given address of all ‘don’t cares’ as well as a broadcast
address of all ‘don’t cares’. This effectively disables the
automatic addressing mode and allows the microcontroller
to use standard 80C51 type UART drivers which do not
make use of this feature.
Table 17 Slave 0
REGISTER
SADDR
SADEN
Given
VALUE (BINARY)
1100 0000
1111 1001
1100 0XX0
2003 Oct 30
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