nrf: etm-trace for nrf52840dk and nrf5340dk

nrf52840dk: 16 MHz TRACECLK (hardware cap) width 4, P25 soldered, SW7=Alt;
no family code needed (J-Link arms TRACECONFIG). nrf5340dk: TRACE_ETM
builds force the TAD port to 16 MHz (SystemInit's 64 MHz is marginal),
+3 ns sample timing; the interface MCU's UART1 flow control drives the
trace pins - SB27/SB28 must be cut (P0.10/P0.11 = TRACEDATA1/0).

3 files changed, 12 insertions, 2 deletions

diff --git a/hw/bsp/nrf/boards/nrf52840dk/ozone/nrf52840.jdebug b/hw/bsp/nrf/boards/nrf52840dk/ozone/nrf52840.jdebug
index fa7ab9e23..40f28baa9 100644
--- a/hw/bsp/nrf/boards/nrf52840dk/ozone/nrf52840.jdebug
+++ b/hw/bsp/nrf/boards/nrf52840dk/ozone/nrf52840.jdebug
@@ -21,7 +21,7 @@ void OnProjectLoad (void) {
   Project.SetTracePortWidth (4);
 
   // User settings
-  File.Open ("../../../../../../examples/device/cdc_msc/cmake-build-pca10056/cdc_msc.elf");
+  File.Open ("../../../../../../examples/cmake-build-nrf52840dk/device/cdc_msc/cdc_msc.elf");
 }
 
 /*********************************************************************
diff --git a/hw/bsp/nrf/boards/nrf5340dk/ozone/nrf5340.jdebug b/hw/bsp/nrf/boards/nrf5340dk/ozone/nrf5340.jdebug
index 4ad0376a4..34b1841b0 100644
--- a/hw/bsp/nrf/boards/nrf5340dk/ozone/nrf5340.jdebug
+++ b/hw/bsp/nrf/boards/nrf5340dk/ozone/nrf5340.jdebug
@@ -29,9 +29,13 @@ void OnProjectLoad (void) {
 
   Project.SetTraceSource ("Trace Pins");
   Project.SetTracePortWidth (4);
+  // +3 ns sample point: the DK's analog-switch/SWO stubs make TD=0 marginal
+  // (Ozone sends TraceSampleAdjust TD=0 when no timing is set); solid across
+  // the +2..+4 ns band with SB27/SB28 cut, SB57 (SWO) left intact
+  Project.SetTraceTiming (3000, 3000, 3000, 3000);
 
   // User settings
-  File.Open ("../../../../../../examples/device/cdc_msc/cmake-build-pca10095/cdc_msc.elf");
+  File.Open ("../../../../../../examples/cmake-build-nrf5340dk/device/cdc_msc/cdc_msc.elf");
 }
 
 /*********************************************************************
diff --git a/hw/bsp/nrf/family.c b/hw/bsp/nrf/family.c
index 31a6bac9e..3cef4dac3 100644
--- a/hw/bsp/nrf/family.c
+++ b/hw/bsp/nrf/family.c
@@ -165,6 +165,12 @@ static nrfx_gpiote_t _gpiote = NRFX_GPIOTE_INSTANCE(0);
 //
 //--------------------------------------------------------------------+
 void board_init(void) {
+#if defined(TRACE_ETM) && defined(NRF5340_XXAA)
+  // SystemInit (ENABLE_TRACE) sets the TAD trace port to 64 MHz, which is
+  // marginal through the DK's switch stubs - 16 MHz streams reliably (matches the validated nrf52840dk) and is
+  // ample bandwidth for the 64 MHz core
+  NRF_TAD_S->TRACEPORTSPEED = TAD_TRACEPORTSPEED_TRACEPORTSPEED_16MHz;
+#endif
 #if !defined(NRF54H20_XXAA) && !defined(NRF54LM20A_ENGA_XXAA)
   // stop LF clock just in case we jump from application without reset
   NRF_CLOCK->TASKS_LFCLKSTOP = 1UL;