Programmer’s Model
3-8
Copyright © 2002, 2003 ARM Limited. All rights reserved.
ARM DDI 0275D
When read, the RAM Read Pointer Register returns the current trace RAM read address.
You cannot write to this register if
TraceCaptEn
is HIGH.
This register is not accessible from the AHB interface because the RAM is
memory-mapped. See
Software access to the ETB11 using the AHB interface
3.2.7
RAM Write Pointer Register, r6
This read/write register enables you to set and read the pointer used to write entries from
the ETM11RV into the RAM. Register bit allocations for the RAM Write Pointer
Register are listed in Table 3-8.
Note
ETB_ADDR_WIDTH
is a constant used to define the width of the trace RAM address bus.
You cannot write to this register if
TraceCaptEn
is HIGH.
The initial value of the trace memory write address pointer is set by writing to the RAM
Write Pointer Register. You must program the pointer before tracing starts. In most
circumstances the initial pointer value is zero. During trace capture, the pointer
increments when the DataValid flag is asserted by the Data Formatter. When the RAM
Write Pointer Register value increments from its maximum value back to zero, the Full
flag is set.
Reading the RAM Write Pointer Register returns the current trace RAM write address.
During trace capture, write pointer changes might be asynchronous. For example, if
DBGTCK
is not related to the CPU clock, in this case the read back value is
indeterminate. This register only returns the correct write pointer value when trace
acquisition is stopped (when the AcqComp status bit is set or trace capture is disabled).
Table 3-8 RAM Write Pointer Register bit allocations
Bit number
Function
[31: ETB_ADDR_WIDTH]
Reserved
[(ETB_ADDR_WIDTH-1):0]
RAM write pointer
Summary of Contents for ETB11
Page 6: ...List of Tables vi Copyright 2002 2003 ARM Limited All rights reserved ARM DDI 0275D ...
Page 8: ...List of Figures viii Copyright 2002 2003 ARM Limited All rights reserved ARM DDI 0275D ...
Page 46: ...Functional Description 2 26 Copyright 2002 2003 ARM Limited All rights reserved ARM DDI 0275D ...
Page 70: ...Signal Descriptions A 6 Copyright 2002 2003 ARM Limited All rights reserved ARM DDI 0275D ...
Page 78: ...Glossary Glossary 4 Copyright 2002 2003 ARM Limited All rights reserved ARM DDI 0275D ...