ATR2731 Datasheet, PDF (12/26 Pages) ATMEL Corporation – DAB One-chip Front End

8. Simple Two-wire Bus Interface
Via its two-wire bus interface, various functions can be controlled by a microprocessor. These
functions are outlined in Table 8-1 on page 12, and in Section 8.1 ”Simple Two-wire Bus Func-
tions” on page 12. The programming information is stored in a set of internal registers. By means
of the pin ADR, two different two-wire bus addresses can be selected, as described in “Electrical
Characteristics” on page 16. Figure 8-1 on page 14 shows the two-wire bus timing parameters;
Figure 8-2 on page 14 shows a typical two-wire bus pulse diagram.
Table 8-1. Simple Two-wire Bus Instruction Codes
Description
MSB
Address
1
1
0
A byte 1
0
0
X
A byte 2
A byte 3
B byte 1
X
X
n₁₁
X
X
n₅
0
1
X
B byte 2
B byte 3
C byte 1
r₇
r₆
r₅
r₃
r₂
r₁
1
0
X
C byte 2
CA7
CA6
CA5
C byte 3
CB7
CB6
CB5
D byte 1
1
1
0
D byte 2
SWA
SWB
SWC
D byte 3
CC7
CC6
CC5
0
X
n₁₀
n₄
r₈
r₄
r₀
X
CA4
CB4
OS
X
CC4
0
X
n₉
n₃
TA3
TB3
TC3
X
CA3
CB3
T
M3
CC3
AS1
n₁₄
n₈
n₂
TA2
TB2
TC2
X
CA2
CB2
TRI
M2
CC2
0
n₁₃
n₇
n₁
TA1
TB1
TC1
X
CA1
CB1
I100
M1
CC1
LSB
0
n₁₂
n₆
n₀
TA0
TB0
TC0
X
CA0
CB0
I50
M0
CC0
8.1 Simple Two-wire Bus Functions
AS1
Defines the two-wire bus address
n_i
Effective scaling factor (SF_eff) of the main divider SF_eff = _∑n_i × 2ⁱ
r_i
Scaling factor (SF_ref,eff) of the reference divider SF_ref,eff = 4 × r_i 2ⁱ
TAi
Define the setting of a 4-bit D/A converter controlling the threshold, th1, of the
RF AGC to adjust the controlled output power
TBi
Define the setting of a 4-bit D/A converter controlling the threshold, th2,
which determines the activation voltage for the internal RF AGC
TCi
Define the setting of a 4-bit D/A converter controlling the threshold, th3, of the
IF AGC to adjust the output power
CAi, CBi, CCi Define the setting of the three D/A converters A, B and C (i = 0, ..., 7)
OS
OS = High switches off the tuning output
T
For T = High, reference signals describing the output frequencies of the refer-
ence divider and programmable divider are monitored at SWA (reference
divider) and SWC (programmable divider).
TRI
TRI = High switches off the charge pump
12 ATR2731
4904A–DAB–03/06