TDA8029 Philips Semiconductors, TDA8029 Datasheet - Page 24

• Manufacturer Part Number: TDA8029
• Description: Low power single card reader
• Manufacturer: Philips Semiconductors

Philips Semiconductors
Note
1. Do not write logic 1s to reserved bits. These bits may be used in future 80C51 family products to invoke new features.
8.5
The dual DPTR structure is a way by which the TDA8029
will specify the address of an external data memory
location. There are two 16-bit DPTR registers that address
the external memory, and a single bit called DPS (bit 0 of
the AUXR1 register) that allows the program code to
switch between them.
The DPS bit should be saved by software when switching
between DPTR0 and DPTR1.
The GF bit (bit 2 in register AUXR1) is a general purpose
user-defined flag. Note that bit 2 is not writable and is
always read as a logic 0. This allows the DPS bit to be
quickly toggled simply by executing an INC AUXR1
instruction without affecting the GF or LPEP bits.
The instructions that refer to DPTR refer to the data pointer
that is currently selected using bit 0 of the AUXR1 register.
The six instructions that use the DPTR are listed in
Table 28 and an illustration is given in Fig.8.
2003 Oct 30
handbook, full pagewidth
Low power single card reader
In that case, the reset or inactive value of the new bit will be logic 0, and its active value will be logic 1. The value
read from a reserved bit is indeterminate.
BIT
2
1
0
Dual Data Pointer (DPTR)
PX1H
PT0H
PX0H
SYMBOL
AUXR1.0
DPS
External interrupt 1 priority. See Table 20.
Timer 0 interrupt priority. See Table 20.
External interrupt 0 priority. See Table 20.
(83H)
DPH
(82H)
DPL
Fig.8 Dual DPTR.
DPTR1
DPTR0
24
Table 28 DPTR instructions
The data pointer can be accessed on a byte-by-byte basis
by specifying the low or high byte in an instruction which
accesses the SFRs.
INC DPTR
MOV DPTR, #data 16 loads the DPTR with a 16-bit
MOV A, @A + DPTR
MOVX A, @DPTR
MOVX @DPTR, A
JMP @A + DPTR
INSTRUCTION
DESCRIPTION
EXTERNAL
MEMORY
DATA
increments the data pointer by 1
constant
move code byte relative to
DPTR to ACC
move external RAM (16-bit
address) to ACC
move ACC to external RAM
(16-bit address)
jump indirect relative to DPTR
MHI007
COMMENT
Product specification
TDA8029