Controlling Protocol ......
Tx Tone Generator Registers 1 and 2
Each Tx Tone Generator is controlled individually by writing a two-byte command to the relevant Tx Tone Generator
Register. The format of this command word, which is different for each tone generator, is shown below with the calculations
required for tone frequency (f
TONE
) generation described in the following text.
“Write to Tx Tone Generator 1 Register”
– A/C 34
H
followed by 2 bytes of Command Data.
MSB
(loaded first)
15
14
Bit Numbers
13
12
11
10
9
8
7
6
5
4
3
2
LSB
(loaded last)
1
0
“0”
“0”
Enable
V
BIAS
/
These 13 bits (0 to 12) are used to produce a binary number, designated “A.”
“A” is used in the formulas below to set the Tx Tone 1 frequency (f
TONE
1).
Bit 13 at logic “1” = Tone 1 Output at V
BIAS
(N
OTONE
).
“0” = Tone 1 Output Enabled.
Bits 14 and 15 (
MSB
) must be logic “0.”
The binary number produced by bits 0 to 12 (
MSB
) is
designated "A."
If “A” = all logic “0” then Tx Tone Generator 1 is
Powersaved.
Table 4 Setting Tx Tone Generator 1
“Write to Tx Tone Generator 2 Register”
– A/C 35
H
followed by 2 bytes of Command Data.
MSB
(loaded first)
15
14
“0”
Bit Numbers
13
12
11
10
9
8
7
6
5
4
3
2
LSB
(loaded last)
1
0
CAL/
CUES
V
BIAS
/
Enable
These 13 bits (0 to 12) are used to produce a binary number, designated “B.”
“B”
is used in the formulas below to set the Tx Tone 2 frequency (f
TONE
2).
Bit 13 at logic “1” = Tone 1 Output at V
BIAS
(N
OTONE
).
“0” = Tone 1 Output Enabled.
Bit 14 at logic “1” = Squarewave CAL Output.
“0” = Sinewave CUES Output.
Bit 15 (
MSB
) must be a logic “0.”
The binary number produced by bits 0 to 12 (
MSB
) is
designated "B."
If “B” = all logic “0” then Tx Tone Generator 2 is
Powersaved.
Table 5 Setting Tx Tone Generator 2
Notes
(1) Programming Tone Generator 2 to V
BIAS
(N
OTONE
) (Bit 13) will place the CAL/CUES Output at V
BIAS
via a 40kΩ
internal resistor.
(2) Programming Tone Generator 2 to Powersave will place the CAL/CUES Output at V
SS
.
(3) If both Tone Generators (1 and 2) are Powersaved, the Summing Amplifier is also Powersaved.
Calculations
As can be seen from Tables 4 and 5 (above), a binary number (“A” or “B” – Bits 0 to 12) is loaded to the respective Tx Tone
Generator. The formulas shown below are used to calculate the required output frequency.
Required Tx Tone output frequency
X
TAL
/clock frequency
Input Data Word (Bits 0 to 12)
=
=
=
f
TONE
1 or 2
f
XTAL
“A” or “B”
Formula
f
TONE
(H )
=
Z
f
XTAL
(H )
Z
or
Input “A” (or “B”)
= f
XTAL
(H )
Z
4 x “A” (or “B”)
Tx Tone Frequencies
4 x f
TONE
(H )
Z
With reference to Tables 4 and 5 (above), whilst Input Data Words “A” or “B” can be programmed for frequencies outside the
stated limits of 208Hz and 3000Hz, any output frequencies obtained may not be within specified parameters
(see “Specification” page).
7
CMLMICRO [ CML MICROCIRCUITS ]
