U2731B Datasheet, PDF (11/25 Pages) ATMEL Corporation – DAB ONE- CHIP FRONT END

U2731B
Simple Two-wire Bus
Interface
Via its two-wire bus interface, various functions can be controlled by a microprocessor.
These functions are outlined in the following table “Simple Two-wire Bus Instruction
Codes” on page 11 and in the section “Simple Two-wire Bus Functions” on page 11. 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 the section
“Electrical Characteristics”. In Figure 6 on page 19, the two-wire bus timing parameters
are explained, Figure 7 on page 20 shows a typical two-wire bus pulse diagram.
Table 3. Simple Two-wire Bus Instruction Codes
Description
MSB
Address
1
1
A byte 1
0
0
A byte 2
X
X
A byte 3
X
X
B byte 1
0
1
B byte 2
B byte 3
C byte 1
r₇
r₆
r₃
r₂
1
0
C byte 2
CA7
CA6
C byte 3
CB7
CB6
D byte 1
1
1
D byte 2
SWA
SWB
D byte 3
CC7
CC6
0
X
n₁₁
n₅
X
r₅
r₁
X
CA5
CB5
0
SWC
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
Simple Two-wire Bus
Functions
4671C–DAB–06/04
AS1
Defines the two-wire bus address
n_i
Deffective scaling factor (SFeff) 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 reference divider and programmable divider are monitored at
SWA (reference divider) and SWC (programmable divider).
TRI
TRI = HIGH switches off the charge pump
11