rtl872x: overshoot issue #2680
rtl872x: overshoot issue #2680
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hal/inc/gpio_hal.h
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| @@ -73,6 +73,8 @@ PinMode hal_gpio_get_mode(hal_pin_t pin); | |||
| void hal_gpio_write(hal_pin_t pin, uint8_t value); | |||
| int32_t hal_gpio_read(hal_pin_t pin); | |||
| uint32_t hal_gpio_pulse_in(hal_pin_t pin, uint16_t value); | |||
| hal_gpio_drive_t hal_gpio_get_drive_strength(hal_pin_t pin); | |||
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Nit: If we are later to expose this in dynalib might perhaps be better to do int hal_gpio_get_drive_strength(hal_pin_t hal_gpio_drive_t* drive) to catch errors (e.g. wrong pin, input only pin etc).
hal/src/rtl872x/gpio_hal.cpp
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| return drive; | ||
| } | ||
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| int hal_gpio_configure_drive_strength(hal_pin_t pin, hal_gpio_drive_t drive) { |
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hal_gpio_config_t::drive_strength should also be handled in hal_gpio_configure, right?
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Yes, set to HAL_GPIO_DRIVE_DEFAULT in the hal_gpio_configure
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Hm. What I meant is that it should be called in hal_gpio_configure with that field as argument, so hal_gpio_configure(pin, config->drive_strength)
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I misunderstood that, I'll rework this API
hal/src/rtl872x/gpio_hal.cpp
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| return SYSTEM_ERROR_NONE; | ||
| } | ||
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| int hal_gpio_configure_drive_strength(hal_pin_t pin, hal_gpio_drive_t drive) { |
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Would it be clearer if this function was renamed hal_gpio_set_drive_strength() to match hal_gpio_get_drive_strength()?
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To be honest, I'd also prefer hal_gpio_set_drive_strength(), I intended to keep it consistent with hal_gpio_configure, well, let's rename it.
… configuration for high speed buses
…GPIO_DRIVE_DEFAULT
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Problem
During the EVT test, we observed significant overshoot. This issue occurs on every high-speed bus, including SPI, I2C, PWM, I2S, and DMIC.
Solution
There are four drive strength can be configured for RTL872x, all the GPIO were configured to
PAD_DRV_STRENGTH_3at boot.We compared the overshoot issue with each drive strength configuration and found
PAD_DRV_STRENGTH_0andPAD_DRV_STRENGTH_2were better thanPAD_DRV_STRENGTH_1andPAD_DRV_STRENGTH_3Below is the clock pin of SPI0@50MHz
Selecting PAD_DRV_STRENGTH_2 could be a solution to avoid the overshoot issue while maintaining a high drive strength.
Below, you will find a more detailed comparison between PAD_DRV_STRENGTH_2 and PAD_DRV_STRENGTH_3 across different buses on the Orson platform.
Steps to Test
References
[CH119867]
[CH119866]
[CH120087]
[CH119868]
Completeness