Messages in this thread | | | From | Nylon Chen <> | Subject | [PATCH 0/2] Change PWM-controlled LED pin active mode and algorithm | Date | Fri, 13 Jan 2023 16:31:13 +0800 |
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According to the circuit diagram of User LEDs - RGB described in the manual hifive-unmatched-schematics-v3.pdf[0]. The behavior of PWM is acitve-high.
According to the descriptionof PWM for pwmcmp in SiFive FU740-C000 Manual[1]. The pwm algorithm is (PW) pulse active time = (D) duty * (T) period[2]. The `frac` variable is pulse "inactive" time so we need to invert it.
So this patchset removes active-low in DTS and adds reverse logic to the driver.
[0]:https://sifive-china.oss-cn-zhangjiakou.aliyuncs.com/HiFIve%20Unmatched/hifive-unmatched-schematics-v3.pdf [1]:https://sifive-china.oss-cn-zhangjiakou.aliyuncs.com/HiFIve%20Unmatched/fu740-c000-manual-v1p2.pdf [2]:https://en.wikipedia.org/wiki/Duty_cycle
Nylon Chen (2): riscv: dts: sifive unmatched: Remove PWM controlled LED's active-low properties pwm: sifive: change the PWM controlled LED algorithm
arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts | 4 ---- drivers/pwm/pwm-sifive.c | 1 + 2 files changed, 1 insertion(+), 4 deletions(-)
-- 2.36.1
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