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sys/ztimer: mention ztimer_auto_adjust in relevant places #21003

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Merged
maribu merged 2 commits into from
Nov 21, 2024
Merged

sys/ztimer: mention ztimer_auto_adjust in relevant places #21003

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28ec1c5
tests/sys/ztimer_overhead: mention auto_adjust in README and fix typos
mguetschow Nov 18, 2024
a2ef45f
doc: mention auto_adjust in relevant section of porting-boards.md
mguetschow Nov 18, 2024
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10 changes: 7 additions & 3 deletions doc/doxygen/src/porting-boards.md
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Expand Up @@ -178,13 +178,13 @@ PROGRAMMER ?= openocd

## Timer Configurations {#board-timer-configurations}

When using high level timers, i.e. `ztimer` there is an overhead in calling
for @ref ztimer_sleep and @ref ztimer_set functions. This offset can be
When using the high level timer `ztimer` there is an overhead in calling
the @ref ztimer_sleep and @ref ztimer_set functions. This offset can be
compensated for. It can be measured by running `tests/sys/ztimer_overhead`
on your board, i.e:

```shell
$ BOARD=my-new-board make -C tests/sys/ztimer_overhead
$ BOARD=my-new-board make -C tests/sys/ztimer_overhead flash term
main(): This is RIOT!
ZTIMER_USEC auto_adjust params:
ZTIMER_USEC->adjust_set = xx
Expand All @@ -211,6 +211,10 @@ The last two lines can be added as defines to the new board `board.h`:
/** @} */
```

Alternatively, the pseudomodule @ref pseudomodule_ztimer_auto_adjust can be used
in an application to enable automatic timer offset compensation at board startup.
This however incurs overhead both in the text segment and at bootup time.

## doc.txt {#board-doc}

Although not explicitly needed, if upstreamed and as a general good
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4 changes: 4 additions & 0 deletions tests/sys/ztimer_overhead/README.md
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Expand Up @@ -22,3 +22,7 @@ ZTIMER_USEC adjust params for dwm1001:
CONFIG_ZTIMER_USEC_ADJUST_SET 6
CONFIG_ZTIMER_USEC_ADJUST_SLEEP 21
```

This test application also makes use of the `ztimer_auto_adjust` pseudomodule
and thereby allows for comparison of the offset values calculated during
auto-initialization and later during this test.
4 changes: 2 additions & 2 deletions tests/sys/ztimer_overhead/main.c
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Expand Up @@ -67,9 +67,9 @@ int main(void)
ZTIMER_USEC->adjust_sleep = 0;
printf("ZTIMER_USEC auto_adjust params cleared\n");

printf("zitmer_overhead_set...\n");
printf("ztimer_overhead_set...\n");
ZTIMER_USEC->adjust_set = _ztimer_usec_overhead(SAMPLES, BASE, ztimer_overhead_set);
printf("zitmer_overhead_sleep...\n");
printf("ztimer_overhead_sleep...\n");
ZTIMER_USEC->adjust_sleep = _ztimer_usec_overhead(SAMPLES, BASE, ztimer_overhead_sleep);
printf("ZTIMER_USEC adjust params for %s:\n", RIOT_BOARD);
printf(" CONFIG_ZTIMER_USEC_ADJUST_SET %" PRIi16 "\n", ZTIMER_USEC->adjust_set);
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