Hardware Registers; Configuration Registers - SIGNALCORE SC5312A User Manual

4 Hardware Registers

The set of hardware registers of the downconverter may be divided into a configuration set and a query
set; the configuration registers are write-only registers to set up the states of the device, while the query
registers request the device to prepare and send back data associated with them. The registers are
identical for all communication interfaces: PXIe, USB, RS232, and SPI. Data communication to all
interfaces are sent in 1 byte wide, that is, data is transferred byte-by-byte. Register data lengths vary in
size, and it is important that the correct number of bytes are sent for the corresponding register. Failure
to do so may cause communication to lock-up and the device to become unresponsive.

Configuration Registers

These are write-only registers to configure the device. The registers vary in length to reduce redundant
data and improve the communication speed, especially for SPI and RS232 interfaces. Furthermore, it is
vitally important that the length of data written to a register is exact because failure to do so will cause
the interfaces to misinterpret the incoming data, leaving the device in a stalled state. The total number of
bytes is the sum of the register address (1 Byte) and its corresponding data bytes. For example, to set the
RF frequency value, eight bytes must be written; the sum of the 1 register byte and 7 data bytes. See the
RF_FREQUENCY register of Table 3. The table provides a summary of the configuration registers, and each
register is explained in detail.
Register Name Reg Add
INITIALIZE 0x01
SYSTEM_ACTIVE 0x02
SYNTH_MODE 0x03
RF_FREQUENCY 0x10
IF_FREQUENCY 0x11
RF_AMP 0x14
ATTENUATOR 0x15
SIGNAL_PATH 0x16
©2013
Table 3. Configuration Registers
Serial
Bit 7 Bit 6
Range
[7:0] Set to zeros [7:1]
[7:0] Set to zeros [7:1]
[7:0] Set to zeros [7:2]
[7:0] Frequency Word (Hz) [7:0]
[15:8] Frequency Word (Hz) [15:8]
[23:16] Frequency Word (Hz) [23:16]
[31:24] Frequency Word (Hz) [31:24]
[39:32] Frequency Word (Hz) [39:32]
[47:40] Frequency Word (Hz) [47:40]
[55:48] Set to zeros
[7:0] Frequency Word (Hz) [7:0]
[15:8] Frequency Word (Hz) [15:8]
[23:16] Frequency Word (Hz) [23:16]
[31:24] Frequency Word (Hz) [31:24]
[39:32] Frequency Word (Hz) [39:32]
[47:40] Frequency Word (Hz) [47:40]
[55:48] Set to zeros
[7:0] Set to zeros [7:1]
[7:0] 0 Attenuator value
[15:8] Set to zeros [15:11]
[23:16] Set to zeros [23:16]
If3
[7:0] fil#2 If3 fil#1 select
select
[15:8] Set to zeros [15:10]
Hardware Registers
Bit 5 Bit 4 Bit 3 Bit 2
Fast-
tune
Attenuator Number
IF2 Bypass
filter 0 IF3
select conv
15
Bit 1 Bit 0
Mode
Enable
"active"
LED
Loop Gain
LO
Enable
Ext. IF2 Bypass
select convert
Rf amp invert
Rev 2.1