© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
316
Philips Semiconductors
UM10139
Volume 1
Chapter 23: Embedded Trace
[1]
For details refer to ARM documentation "Embedded Trace Macrocell Specification (ARM IHI 0014E)".
23.4 Pin description
23.5 Reset state of multiplexed pins
On the LPC2141/2/4/6/8, the ETM pin functions are multiplexed with P1.25-16. To have
these pins come as a Trace port, connect a weak bias resistor (4.7 k
Ω
) between the
P1.20/TRACESYNC pin and V
SS
. To have them come up as port pins, do not connect a
bias resistor to P1.20/TRACESYNC, and ensure that any external driver connected to
P1.20/TRACESYNC is either driving high, or is in high-impedance state, during Reset.
External Inputs
2
External Outputs
0
FIFOFULL Present
Yes (Not wired)
FIFO depth
10 bytes
Trace Packet Width
4/8
Table 317: ETM configuration
Resource number/type
Small
[1]
Table 318: ETM pin description
Pin Name
Type
Description
TRACECLK
Output Trace Clock. The trace clock signal provides the clock for the trace
port. PIPESTAT[2:0], TRACESYNC, and TRACEPKT[3:0] signals are
referenced to the rising edge of the trace clock. This clock is not
generated by the ETM block. It is to be derived from the system clock.
The clock should be balanced to provide sufficient hold time for the
trace data signals. Half rate clocking mode is supported. Trace data
signals should be shifted by a clock phase from TRACECLK. Refer to
Figure 3.14 page 3.26 and figure 3.15 page 3.27 in "ETM7 Technical
Reference Manual" (ARM DDI 0158B), for example circuits that
implements both half-rate clocking and shifting of the trace data with
respect to the clock. For TRACECLK timings refer to section 5.2 on
page 5-13 in "Embedded Trace Macrocell Specification" (ARM IHI
0014E).
PIPESTAT[2:0]
Output Pipe Line status. The pipeline status signals provide a cycle-by-cycle
indication of what is happening in the execution stage of the processor
pipeline.
TRACESYNC
Output Trace synchronization. The trace sync signal is used to indicate the
first packet of a group of trace packets and is asserted HIGH only for
the first packet of any branch address.
TRACEPKT[3:0] Output Trace Packet. The trace packet signals are used to output packaged
address and data information related to the pipeline status. All packets
are eight bits in length. A packet is output over two cycles. In the first
cycle, Packet[3:0] is output and in the second cycle, Packet[7:4] is
output.
EXTIN[0]
Input
External Trigger Input