16
FN6004.3
July 8, 2005
4-Channel Summers
Cascade Input
When in the complex cascade mode the 4-channel summer
re 1 and im 1 are summed with the real and imaginary
cascade inputs. The cascade input allows for more than four
multi-channel transmissions by summing the complex
modulated signals from other device’s. A cascade chain of
four devices allows up to sixteen carriers. Figure 15
illustrates cascading multiple devices. Each device delays it’s
4-channel summation to align with the cascade in from the
previous device. Device Control 0x78, bits 2:1 identifies the
position in the cascade chain. Device Control 0x78, bit 3
zeroes the cascade-in data when the port is not in use. The
output of the summation is saturated to prevent roll-over.
Output Formatter
The output can be formatted in either twos complement or
offset binary. The OFFBIN pin is used to select the output
format. The output ranges from 0x8001 to 0x7FFF for two’s
complement and from 0x0001 - 0xFFFF for offset binary.
Microprocessor Interface
NOTE: See Appendix A, Errata Sheet
The microprocessor interface allows the QPUC to appear as
a memory mapped peripheral to the
μ
P. Configuration data,
I/Q sample data and RAM data can be accessed through
this interface. The interface consists of a 16 bit bidirectional
data bus, P<15:0>, seven bit address bus, A<6:0>, a write
strobe (WR), a read strobe (RD) and a chip enable (CE).
Two
μ
P interface modes are supported through the input pin
RDMODE
.
When low the device is configured for separate
read and write strobe inputs. When high the device is
configured for a common Read/Write and data strobe inputs
.
This mode redefines RD into Read/Write Strobe and WR
into Data Strobe.
The address space is partitioned into five directly accessible
regions, one for top control and one for each of the four
channels. The Device Control space allows for configuration
parameters that effect the entire device, cascade, output
modes, and routing. The channel space allows for
configuration parameters and sample data.
The master registers for the configuration data and I/Q
sample data are located in these areas. There is a master
TABLE 8. INPUT/OUTPUT MODES
MAIN CONTROL 0X78, BITS
9:8 OUTPUT MODE
OUTEN
<1:0>
IIN
<19:0>
QIN
<19:0>
IOUT
<19:0>
QOUT
<19:0>
00
00
Input
Input
Output
Output
00
01
Input
Input
Output
HI-Z
00
10
Input
Input
HI-Z
Output
00
11
Input
Input
HI-Z
HI-Z
01,10,11
00
Output
Output
Output
Output
01,10,11
01
Output
Input
Output
HI-Z
01,10,11
10
Input
Output
HI-Z
Output
01,10,11
11
Input
Input
HI-Z
HI-Z
FIGURE 15. CASCADED QPUCs
μ
P
SCLKX
FSRX
SDX
MASTER
ISL5217
QPUC
SLAVE
ISL5217
QPUC
Q OUT <19:0>
SYNCO
I IN <19:0>
I OUT <19:0>
Q IN <19:0>
I OUT <19:0>
SLAVE
ISL5217
QPUC
SLAVE
ISL5217
QPUC
μ
P
SCLKX
FSRX
SDX
μ
P
SCLKX
FSRX
SDX
μ
P
SCLKX
FSRX
SDX
UPDX
Q OUT <19:0>
I IN <19:0>
I OUT <19:0>
Q IN <19:0>
UPDX
Q OUT <19:0>
I IN <19:0>
I OUT <19:0>
Q IN <19:0>
UPDX
Q OUT <19:0>
FIGURE 16. CASCADE INPUT BLOCK DIAGRAM
21
ALL REGISTERS ARE CLOCKED AT CLK
SATURATE
CIRCUITRY
I IN<19:0>
CASZ
MOD(20:0)
20
∑
R
E
G
>
R
E
G
>
20
I OUT<19:0>
22
ISL5217