cpu/qn908x/periph_i2c: allow internal pull-up on SCL #19729
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cpu/qn908x/include/periph_cpu.h
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| @@ -366,6 +366,7 @@ typedef struct { | |||
| gpio_t pin_scl; /**< SCL pin */ | |||
| gpio_t pin_sda; /**< SDA pin */ | |||
| uint32_t speed; /**< bus speed in bit/s */ | |||
| bool external_pull_up; /**< Do not enable internal pull-up on SCL? */ | |||
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Does anything speak against always enabling this?
That's now it's done on e.g. nRF5x
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At least in theory this could reduce power consumption while the SCL is driven low by the controller / clock-stretched by the peripheral.
E.g. if a 3.3 V SCL line is driven low and there is a
but e.g. with
But then again, a weaker pull up results in a lower data rate and therefore would consume the current over a longer period of time.
Maybe its best to just enable it always until someone has a real world example where it is beneficial to only have the external pull up.
Always enable the internal pull-up on the SCL line to always have a functional I2C bus. This may increase power consumption where an external pull up is present as well. But let's wait for a real world use case where this would help to extend battery life before making this configurable. This fixes RIOT-OS#19021
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19724: dist/tools/openocd: add OPENOCD_SERVER_ADDRESS variable r=maribu a=fabian18 19729: cpu/qn908x/periph_i2c: allow internal pull-up on SCL r=maribu a=maribu ### Contribution description Allow the board config to specify use of external or external pull-up resistor on the SCL up. Default to the internal pull-up, two weak pull ups in parallel are preferable over no pull-up. Co-authored-by: Fabian Hüßler <fabian.huessler@ml-pa.com> Co-authored-by: Marian Buschsieweke <marian.buschsieweke@posteo.net>
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Contribution description
Allow the board config to specify use of external or external pull-up resistor on the SCL up. Default to the internal pull-up, two weak pull ups in parallel are preferable over no pull-up.
Testing procedure
On
master: No output at all, board hangs.This PR:
(Note: The mma8x5x is connected via I2C and the driver hangs in master during the first I2C access due to bogus clock stretching due to the missing pull-up.)
Issues/PRs references
This fixes #19021