From dd3c7db0ad1f116d7e32e07ab0943bc41ba2e0d2 Mon Sep 17 00:00:00 2001
From: recallmenot <104343143+recallmenot@users.noreply.github.com>
Date: Fri, 9 Jun 2023 05:57:53 +0000
Subject: [PATCH] GPIO branchless PWM flicker (#157)
* one GPIO library to rule them all
* GPIO example makefile transfer
* GPIO README.md video upload
* Update README.md
* Update README.md
* GPIO library path recitified
* GPIO pretty paths please
* platformio.ini removed GPIO_analogRead test
* GPIO removed implementation block (unused)
* restoring blink.bin #1
* restoring blink.bin #2
* GPIO_branchless added branching digitalWrite (sometimes necessary)
* GPIO fixed PWM fade flicker
---------
Co-authored-by: recallmenot <edmund.raile@proton.me>
---
extralibs/ch32v003_GPIO_branchless.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/extralibs/ch32v003_GPIO_branchless.h b/extralibs/ch32v003_GPIO_branchless.h
index 455716b..728ee00 100644
--- a/extralibs/ch32v003_GPIO_branchless.h
+++ b/extralibs/ch32v003_GPIO_branchless.h
@@ -80,6 +80,10 @@ This puts the defaults at an inaudible 23.4kHz.
The higher the frequency, the greater the EMI radiation will be.
With low frequencies, say below 1000Hz, LEDs may exhibit perceivable flicker.
+Since this library enables compare capture preload (OCxPE of CHCTLRy), writing a value into the compare register using analogWrite will automatically apply it (=load into shadow register) when the timer starts its next cycle.
+This avoids a bug whereby writing a compare value lower than the current counter value, the output will glitch high for the next cycle, resulting in flickery updates.
+Writing `TIMx->SWEVGR |= TIM_UG` will immediately update the shadow register and cause the same issue.
+
*/
@@ -463,12 +467,10 @@ static inline void GPIO_tim2_init() {
#undef GPIO_tim1_analogWrite
#define GPIO_tim1_analogWrite(channel, value) ({ \
TIM1->GPIO_timer_CVR(channel) = value; \
- TIM1->SWEVGR |= TIM_UG; \
})
#undef GPIO_tim2_analogWrite
#define GPIO_tim2_analogWrite(channel, value) ({ \
TIM2->GPIO_timer_CVR(channel) = value; \
- TIM2->SWEVGR |= TIM_UG; \
})
#endif // CH32V003_GPIO_BR_H
--
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