12 control register settings – Sundance SMT349 User Manual

Page 19

Version 2.1

Page 19 of 32

SMT349 User Manual

11.1

FPGA configuration

You can configure the FPGA by programming the PROM via the JTAG connector
using for instance the Xilinx parallel cable IV.

12 Control Register Settings

The Control Registers control the complete functionality of the SMT349. They are set
up via the Comport 3. The settings of the IF/RF synthesizer, attenuators and RF
switches can be configured via the Control Registers.

12.1 Control Packet Structure

The data passed on to the SMT349 over the Comport must conform to a certain
packet structure. Only valid packets will be accepted and only after acceptance of a
packet will the appropriate settings be implemented. Each packet will start with a
command (4 bits – 0x1 for a write operation – 0x2 for a read operation) information,
followed by a register address (8 bits), followed by a 20-bit data. This structure is
illustrated in the following figure:

Byte

Content

Byte

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Command

Address 7

Address 6

Address 5

Address 4

Address 3

Address 2

Address 1

Address 0

Data 19

Data 18

Data 17

Data 16

Data 15

Data 14

Data 13

Data 12

Data 11

Data 10

Data 9

Data 8

Data 7

Data 6

Data 5

Data 4

Data 3

Data 2

Data 1

Data 0

Table 2- Setup Packet Structure

12.2 Reading and Writing Registers

Control packets are sent to the SMT349 over Comport 3. This is a bi-directional
interface. The format of a ‘Read Packet’ is the same as that of a write packet.