Operation
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Atlas® Digital Amplifier Complete Technical Reference
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4.11.1.1
Trace Buffer
Atlas organizes its internal user memory space into data buffers. Each buffer is given a numerical ID. The trace buffer
must always be ID 0 (zero). Before trace capture may be used, memory buffer 0 must be programmed with a valid
base address and length.
The size of the trace buffer determines the maximum number of data points that can be captured. For the large
majority of applications the trace buffer will be set to a size of 1,020 words, which corresponds to the maximum
available memory for trace. If the external controller specifies some of this area for other functions however, such as
to store a previous trace, the trace buffer must be set to a smaller size.
While trace data is being collected it is not legal to change the trace buffer configuration. If an attempt is made to
change the base address, length, write index, or read index associated with buffer 0 while a trace is running the change
will be ignored and an error will be flagged.
4.11.1.2
Trace Period
The tracing system supports a configurable period register that defines the frequency at which data is stored to the
trace buffer. The tracing frequency is specified in units of 51.2 uSecs.
The command
SetTracePeriod
sets the trace period, and the command
GetTracePeriod
retrieves it. Note that if
the trigger mode is set to external, the trace period is not used.
4.11.1.3
Trace Variables
When traces are running one to four Atlas parameters may be stored to the trace buffer for each occurrence of the
trigger. The four trace variable registers are used to define which parameters are stored.
The command
SetTraceVariable
selects which traceable parameter will be stored by the trace variable specified. The
values passed by this command specify the variable number of the parameter to be traced, and the variable ID. The
command
GetTraceVariable
retrieves this same value.
The following table shows all of the Atlas variables that can be traced along with the variable ID code that is used to
select this variable for tracing.
Trace variables
There are dozens of separate variables and registers within Atlas that may be
traced; for example, the phase A current command, the current loop error, etc…
The user must specify the variables that will be traced by Atlas.
Trace mode
Atlas can trace in one of two modes: one-time, or rolling mode. This determines
how the data is stored, and whether the trace will stop automatically or be
stopped explicitly by the external controller.
Trigger mode
Atlas supports two different methods for determining the moment when data cap-
ture actually occurs. The first is internally, via the Atlas unit’s internal clock cycle
and the trace period defined above. The second is externally commanded by the
external controller via the SPI communication protocol. See
for more information on the SPI protocol. Note that when
external trigger mode is selected the trace period is not used.
Trace Start/Stop
Atlas allows the external controller to control when trace capture starts and
stops. Two overall conditions are supported; starting and stopping immediately via
a command or via the trace bit of the SPI communication header.
Variable ID
Name
Description
Status Registers
12
Event Status
The Event Status register
14
Signal Status
The Signal Status register
56
Drive Status
The Drive Status register
Parameter
Description
