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AD6652
Rev. 0 | Page 51 of 76
PCLKn
PxREQ
PxIQ
PxCH[1:0]
t
DPP
I[15:0]
Q[15:0]
t
DPIQ
PxCH[1:0] =
Channel #
t
DPCH
PxACK
Px[15:0]
t
DPREQ
0
Figure 55. Channel Mode Interleaved Format
The 8-bit concurrent format provides 8 bits of I data and 8 bits
of Q data simultaneously during one PCLK cycle, also triggered
on the rising edge of PCLK. The I byte occupies the most
significant byte of the port, while the Q byte occupies the least
nificant byte. The PAIQ and PBIQ output indicator pins are
t high during the PCLK cycle. Note that if data from multiple
channels is output consecutively, the PAIQ and PBIQ output
indicator pins remain high until data from all channels has been
output.
AGC MODE
Parallel port channel mode is selected by clearing Bit 0 of
Addresses 0x1A and 0x1C for Parallel Ports A and B, respec-
tively. I and Q data output in AGC mode are output from the
AGC, not the individual chann
Channel 0 to Channel 3, while AGC B accepts data from
Channel 2 and Channel 3. Each pair of channels is require
be configu
hat the ge
the ch
f p
port ca
ta from
Bit 2 o
res
contro
o
sig
se
PxCH[1:0]
PCLKn
t
DPREQ
PxREQ
PxACK
t
DPP
Px[15:0]
I[15:8]
Q[7:0]
PxIQ
t
DPIQ
PxCH[1:0] =
Channel #
t
DPCH
0
Figure 56. Channel Mode 8I/8Q Parallel Format
The PACH[1:0] and PBCH[1:0] pins provide a 2-bit binary
value indicating the source channel of the data currently being
output.
Care should be taken to read data from the port as soon as
possible. If not, the sample will be overwritten when the next
new data sample arrives. This occurs on a per-channel basis;
that is, a Channel 0 sample is overwritten only by a new
Channel 0 sample, and so on.
The order of data output is dependent on when data arrived at
the port, which is a function of total decimation rate, start hold-
off values, and so on. Priority order is, from highest to lowest,
Channels 0, 1, 2, and 3.
els. AGC A accepts data from
d to
red such t
annels is out o
n provide da
f Register Add
l the inclusion f data from AGCs A and B, respectively.
neration of output samples from
hase (by typically 180°). Each parallel
either one or both AGCs. Bit 1 and
ses 0x1A (Port A) and 0x1C (Port B)
ode provides only one I&Q format, which is similar to
-bit interleave
ormat of channel mode. When both REQ
K are asserte
he next rising edge of PCLK triggers the
of a 16-bit AGC I word for one PCLK cycle. The PAIQ
and PBIQ output indicator pins are high during this cycle, and
are low otherwise. A 16-bit AGC Q word is provided during the
subsequent PCLK cycle. If the AGC gain word has been updated
since the last sample, a 12-bit RSSI word is provided during the
PCLK cycle following the Q word of 12 MSBs of the parallel
port data pins. This RSSI word is the bit-inverse of the signal
gain word used in the gain multiplier of the AGC.
The data provided by the PACH[1:0] and PBCH[1:0] pins in
AGC mode is different than that provided in channel mode. In
AGC mode, PACH[0] and PBCH[0] indicate the AGC source of
the data currently being output (0 = AGC A, 1 = AGC B).
PACH[1] and PBCH[1] indicate whether the current data is an
I/Q word or an AGC RSSI word (0 = I/Q word, 1 = AGC RSSI
word). The two different AGC outputs are shown in Figure 57
and Figure 58.
AGC m
the 16
and AC
output
d f
d, t
PCLKn
PxREQ
PxACK
Px[15:0]
PxIQ
PxCH[1:0]
t
DPREQ
t
DPP
I[15:0]
Q[15:0]
t
DPIQ
PxCH[0] = AGC #
PxCH[1] = 0
t
DPCH
0
Figure 57. AGC with No RSSI Word