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cpu: efm32: provide non-standard UART modes #9127

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merged 3 commits into from
Jun 4, 2018
Merged

cpu: efm32: provide non-standard UART modes #9127

merged 3 commits into from
Jun 4, 2018

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basilfx
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@basilfx basilfx commented May 13, 2018 •
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Contribution description

I need non-standard UART modes for some (KNX) transceivers that want 8E1. This PR adds them as an option to the uart_config struct, similar to how it was done for some Kinetis boards. The default remains 8N1, for both USART and LEUART.

Conversion methods were added to Gecko-SDK (see this commit), which minimizes the changes in the RIOT code and provides a clean abstraction for both USART and LEUART.

Issues/PRs references

#5899, #7165

@basilfx basilfx added Platform: ARM Platform: This PR/issue effects ARM-based platforms CI: ready for build If set, CI server will compile all applications for all available boards for the labeled PR Area: boards Area: Board ports labels May 13, 2018
@basilfx basilfx requested a review from kYc0o May 14, 2018 06:12
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basilfx commented May 25, 2018

Ping @kYc0o

@basilfx basilfx force-pushed the feature/efm32_uart_modes branch from f28ab62 to 71a4d7e Compare May 25, 2018 09:55
kYc0o
kYc0o reviewed May 25, 2018
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cpu/efm32/periph/uart.c Outdated
@@ -104,6 +109,9 @@ int uart_init(uart_t dev, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)

init.enable = leuartDisable;
init.baudrate = baudrate;
init.databits = LEUART_DataBits2Def((uart_config[dev].mode >> 0) & 0xf);
init.stopbits = LEUART_StopBits2Def((uart_config[dev].mode >> 4) & 0xf);
init.parity = LEUART_Parity2Def((uart_config[dev].mode >> 8) & 0xf);
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So, the baud rate will only change on init, then it stays like that as I see? Which means once the UART is attached to a device it cannot be detached is it?

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@basilfx basilfx May 25, 2018 •
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Yes, that's true. #5899 proposes a runtime option, but it is not merged/fixed/proposed.

STM32 Kinetis does the same, iirc.

kYc0o
kYc0o reviewed May 25, 2018
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pkg/gecko_sdk/Makefile Outdated
@@ -1,6 +1,6 @@
PKG_NAME=gecko_sdk
PKG_URL=https://github.com/basilfx/RIOT-gecko-sdk
PKG_VERSION=d381e526d68a2d0c951f37040c1c2e168ac66cd6
PKG_VERSION=ee01ab57eaaa8805916601dd444d1b63f03037de
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I see there's an update to the gecko sdk. Is this intended here?

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Yeah, the update is intended, as they provide the utility methods to convert bits to enums.

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kYc0o commented May 25, 2018

I also wonder how is this configurable at compile time. The only way to change the behaviour is to modify the source code, which seems not super practical. Maybe you can add an #ifdef on the headers (which would be also a kind of API change, but only as a parameter) and then pass the config through CFLAGS? Otherwise even if there are reasons to have this PR in, it doesn't really give the option and the behaviour stays unchanged (with some additional bytes to the final binary because of the new operations).

@basilfx basilfx force-pushed the feature/efm32_uart_modes branch from 71a4d7e to 02ba86b Compare May 25, 2018 16:10
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basilfx commented May 25, 2018 •
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@kYc0o As we discussed on IRC, I have updated this PR to make this feature optional (in favor of code size, because the current boards/configuration doesn't make use of this feature). I did not make it configurable for each UART interface, since I think that if this is a desired feature, we should fix #5899.

I opted for a solution that I can reuse to make other parts of EFM32 optional, like disabling support for low-power peripherals (if not used). So the last two commits may seem like a lot, I want to re-use them and provide a uniform interface/place for EFM32 specific features/toggles.

Note that Murdock won't test the code, but if you manually test it and provide EFM32_UART_MODES=1 on the command line, you will see that it increases the code size.

@kaibeckmann kaibeckmann mentioned this pull request May 28, 2018
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@basilfx basilfx force-pushed the feature/efm32_uart_modes branch 5 times, most recently from c6fc3c7 to a4734cd Compare June 4, 2018 16:01
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kYc0o commented Jun 4, 2018

Ok, I think we're good here. You may squash.

@basilfx basilfx force-pushed the feature/efm32_uart_modes branch from a4734cd to be29e0a Compare June 4, 2018 16:06
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basilfx commented Jun 4, 2018

Squashed and rebased.

@basilfx basilfx force-pushed the feature/efm32_uart_modes branch from be29e0a to 6789c49 Compare June 4, 2018 16:16
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kYc0o approved these changes Jun 4, 2018
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ACK and go!

@kYc0o kYc0o merged commit 188886d into RIOT-OS:master Jun 4, 2018
This was referenced Jun 11, 2018
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@cladmi cladmi added this to the Release 2018.07 milestone Jul 10, 2018
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@kYc0o kYc0o kYc0o approved these changes

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