SC5506A Operating & Programming Manual
Rev 2.1.1
14
To write to the device through USB transfers such as bulk transfer, it is important to send data with the
register byte first, followed by the most significant bit (MSB) of the data bytes. For example, to set the
RF power level of channel 2 to a particular amplitude, the byte stream would be [0x11][0x01][15:8][7:0].
Initializing the Device
INITIALIZE (0x01)
- Writing 0x00 to this register will reset the device to the default power-on state. Writing
0x01 will reset the device but leave it in the current state. The user has the ability to define the default
startup state by writing to the
STORE STARTUP STATE (0x23)
register, described later in this section.
Setting the System Active LED
SET_SYSTEM_ACTIVE (0x02)
-
This register simply turns on the front panel “active” LED with a write of
0x01 or turns off the LED with a write of 0x00. This register is generally written when the device driver
opens or closes the device.
Setting the RF Frequency
RF_FREQUENCY (0x10)
- This register set the RF frequency for each channel. Data is sent as a 40 bit word
with the LSB in Hz.
Setting the RF Power
RF_POWER (0x11)
- This register sets the RF power level for each channel. The LSB is 1/100th of a dB and
absolute magnitude is carried in the first 15 bits, starting with bit 0. The sign bit is indicated on bit 15.
Setting bit 15 high implies a negative magnitude. For example, to write 10.05 dBm to the register, the data
is simply 1005 (0x03ED). For -10.05 dBm, the data is 33773 (0x83ED).
Setting RF Output Enable
RF_OUT_ENABLE (0x12)
- This register enables or disables the RF signal output for each channel. Setting
bit 0 low (0) disables RF output. Setting bit 0 high (1) enables RF output.
Disabling the Auto Power Feature
AUTO_POWER_DISABLE (0x13)
–
When changing frequency on either channel, the device will calculate
new settings for the amplitude control components such that the amplitude remains the same as the last
setting. If the amplitude is also changed at the new frequency setting, the user has the option to turn off
this auto power adjustment. By default, auto power adjustment is enabled. To disable auto power
adjustment, set bit 0 of this register high (1).
Setting the RF Automatic Level Control (ALC) Mode
RF_ALC_MODE (0x14)
–
For each channel independently, writing 0x00 to this register puts the ALC in a
closed loop operation. Writing 0x01 will run the ALC in an open loop. See the
section to understand the differences between the modes.
