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AD9958
The RU/RD bits control the amplitude RU/RD time of a
channel (see the Output Amplitude Control Mode section).
Rev. 0 | Page 37 of 40
FR1 <12:14> profile pin configuration bits.
The profile pin configuration bits control the configuration of
the data and SDIO pins for the different modulation modes. See
the Modulation Mode section for details.
FR1 <15> open.
FR1 <17:16> charge pump current control.
FR1 <17:16> = 00 (default), the charge pump current is 75 μA.
= 01 charge pump current is 100 μA.
= 10 charge pump current is 125 μA.
= 11 charge pump current is 150 μA.
FR1 <22:18> PLL divider values.
FR1 <22:18>, if the value is > 3 and < 21, the PLL is enabled and
the value sets the multiplication factor. If the value is < 4 or >20
the PLL is disabled.
FR1 <23> PLL VCO gain.
FR1 <23> = 0 (default), the low range (system clock below
160 MHz). FR1 <23> = 1, the high range (system clock above
255 MHz).
Function Register 2 (FR2) Description
The FR2 is comprised of two bytes located in Address 0x02.
The FR2 is used to control the various functions, features, and
modes of the AD9958. The functionality of each bit is detailed
as follows:
FR2<1:0> system clock offset.
See the Synchronizing Multiple AD9958 Devices section for
more details.
FR2 <3:2> open.
FR2 <4> multi-device synchronization mask bit.
FR2 <5> multi-device synchronization status bit.
FR2 <6> multi-device synchronization master enable bit.
FR2<7> multi-device synchronization slave enable bit.
FR2 <4:7>. see the Synchronizing Multiple AD9958 Devices
section for more details.
FR2 <11:8> open.
FR2 <12> both channels clear phase accumulator.
FR2 <12> = 0 (default), the phase accumulator functions as
normal. FR2 <12> = 1, the phase accumulator memory
elements for both channels are asynchronously cleared.
FR2 <13> both channels auto clear phase accumulator.
FR2 <13> = 0 (default). A new frequency tuning word is applied
to the inputs of the phase accumulator, but not loaded into the
accumulator.
FR2 <13> = 1. This bit automatically synchronously clears
(loads zeros into) the phase accumulator for one cycle upon
reception of the I/O update sequence indicator on both
channels.
FR2 <14> both channels clear sweep accumulator.
FR2 <14> = 0 (default), the sweep accumulator functions as
normal.FR2 <14> = 1, the sweep accumulator memory
elements for both channels are asynchronously cleared.
FR2 <15> both channels auto clear sweep accumulator.
FR2 <15> = 0 (default). A new delta word is applied to the
input, as in normal operation, but not loaded into the accumu-
lator. FR2 <15> = 1. This bit automatically synchronously clears
(loads 0s) the sweep accumulator for one cycle upon reception
of the I/O_UPDATE sequence indicator on both channels.
CHANNEL FUNCTION REGISTER (CFR)
DESCRIPTION
CFR <0> enable sine output.
CFR <0> = 0 (default). The angle-to-amplitude conversion logic
employs a cosine function. CFR <0> = 1. The angle-to-
amplitude conversion logic employs a sine function.
CFR <1> clear phase accumulator.
CFR <1> = 0 (default). The phase accumulator functions as
normal. CFR <1> = 1. The phase accumulator memory
elements are asynchronously cleared.
CFR <2> clear phase accumulator.
CFR <2> = 0 (default). A new frequency tuning word is applied
to the inputs of the phase accumulator, but not loaded into the
accumulator. CFR <2> = 1. This bit automatically synchro-
nously clears (loads 0s) the phase accumulator for one cycle
upon reception of the I/O_UPDATE sequence indicator.
CFR <3> clear frequency accumulator.
CFR <3> = 0 (default). The sweep accumulator functions as
normal .CFR <3> = 1. The sweep accumulator memory
elements are asynchronously cleared.
CFR <4> auto clear sweep accumulator.