Debug and Trace features of LPC1769 (LPC17xx family)?

[danielholala]

Hi all,

could anybody please advise on the debug and trace facilities included with the LPC1769 microcontroller?

The LPC176x's fine manual asserts on page 653/658:

"Trace port provides CPU instruction trace capability. Output can be via a 4-bit trace data port, or Serial Wire Viewer." [...]

"LPC176x/5x devices support JTAG and Serial Wire Debug, Serial Wire Viewer, and include the Embedded Trace Macrocell. See Section 33.1 for additional information."

However, the MCUXpresso IDE Instruction Trace Guide claims on page 1/2:

"The MCUXpresso IDE exposes the powerful Embedded Trace Macrocell (ETM) on Cortex M3
and M4 to focus the generated trace stored in the ETB. [...]

Note that Instruction Trace is not supported with LPC17xx MCUs (which do not implement an ETB)..."

Does that mean that Instruction Trace is generally available on LPC17xx but not supported by MCUExpresso IDE?

Thanks.

[converse]

No. It means the ETB hardware is not implemented in LPC17xx. The ETB (when implemented) directs the trace stream to on-chip SRAM, which can then be read out (typically via a debugger) and decoded.

The LPC17xx does generate a trace stream, and this is directed to the trace pins on the chip. You then need specialist hardware (such a Segger JTrace) to capture this stream and then decode it. The trace stream is generated at the same frequency as the CPU core.

[danielholala]

Con Verse wrote:

No. Yes. It means the ETB hardware is not implemented in LPC17xx. The ETB (when implemented) directs the trace stream to on-chip SRAM, which can then be read out (typically via a debugger) and decoded.

The LPC17xx does generate a trace stream, and this is directed to the trace pins on the chip. You then need specialist hardware (such a Segger JTrace) to capture this stream and then decode it. The trace stream is generated at the same frequency as the CPU core.

Thanks Con, for explaining the tracing facility of LPC17xx series µc. But why do you write "No" when my statements do not conflict with your explanation? I corrected this ;-) :smileywink: in the quote.