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Trimble ThunderBolt E GPS Disciplined Clock User Guide 67
Trimble Standard Interface Protocol A
Command Packet 0x8E-A0: Set DAC Value
Use command packet 0x8E-A0 to set the DAC output voltage or to request the current
DAC output voltage plus the parameters describing the DAC. The DAC output voltage
is used to control the frequency of the OCXO (Oven Controlled Crystal Oscillator.)
Send this packet with no data to request the DAC voltage. The receiver responds with
packet 0x8F-A0.
The Command Packet Data Fields are as follows:
To set the DAC voltage, send packet 0x8E-A0 in the format shown below.
Note – Oscillator disciplining must be disabled (see packet 0x8E-A3) to use this command
to set the DAC voltage.
Command Packet 0x8E-A0 Data Format
Command Packet 0x8E-A2: UTC/GPS Timing
Command packet 0x8E-A2 sets the UTC/GPS timing mode (time and date fields) in
packet 0x8F-AB, and the temporal location of ThunderBolt E output PPS. Send packet
0x8E-A2 with no data to request the current settings. The receiver replies with
response packet 0x8F- A2.
Field Description Setting
Voltage/Value flag Use this field to specify that the DAC is to be
set either by value or by voltage.
0: Set DAC by voltage
1: Set DAC by value
DAC Voltage Value: When the Voltage/Value Flag is set to
voltage, use this field to specify the numeric
value of the DAC as the 32-bit unsigned
number.
Voltage: 0.0 V to +4.0 V
Value: 0x00000 to
0xFFFFF (20 bits)
Byte Item Type Value Description
0 Subcode UINT8 0xA0
1 Voltage /Value Flag UINT8 0
1
Set DAC voltage
Set DAC value
2-5 DAC Voltage/ Value Single/UINT3 2 DAC voltage/Value
Byte Bit Item Type Value Meaning
0 Subcode UINT8 0xA2
10
1
UTC/GPS
time
bit field 0
1
GPS time/date in packet 0x8F-AB
UTC time/date in packet 0x8F-AB
bit field 0
1
PPS referenced to GPS time
PPS referenced to UTC time