timers-pwm-baremetal

Name: timers-pwm-baremetal
Author: mohitmishra786

141stars19forks

How to install timers-pwm-baremetal?

mohitmishra786/low-level-dev-skills/timers-pwm-baremetal

$npx -y skills add mohitmishra786/low-level-dev-skills --skill timers-pwm-baremetal

Installs into the current project.

Summary

Bare-metal timer and PWM skill. Use when configuring general-purpose timers for PWM, input capture, or periodic ticks without RTOS. Activates on queries about timer prescaler, PWM duty cycle, input capture, or SysTick bare-metal.

Files · 1

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SKILL.md

1	# Timers and PWM (Bare-Metal)
2
3	## Purpose
4
5	Configure MCU timers for PWM output, input capture, and periodic scheduling: prescaler/ARR setup, compare channels, and SysTick as a simple tick source.
6
7	## When to Use
8
9	- Motor/LED dimming via PWM
10	- Measuring pulse width (input capture)
11	- Bare-metal `millis()` without FreeRTOS
12	- Hardware periodic sampling trigger
13
14	## Workflow
15
16	### 1. PWM on TIM2 CH1 (STM32)
17
18	```
19	f_pwm = f_timer_clk / ((PSC+1) * (ARR+1))
20	duty = (CCR / (ARR+1)) * 100%
21	```
22
23	```c
24	RCC->APB1ENR \|= RCC_APB1ENR_TIM2EN;
25
26	TIM2->PSC = 83; /* 84MHz / 84 = 1 MHz tick */
27	TIM2->ARR = 999; /* 1 kHz PWM */
28	TIM2->CCR1 = 500; /* 50% duty */
29	TIM2->CCMR1 \|= (6U << TIM_CCMR1_OC1M_Pos); /* PWM mode 1 */
30	TIM2->CCER \|= TIM_CCER_CC1E;
31	TIM2->CR1 \|= TIM_CR1_CEN;
32	```
33
34	GPIO: PA0 AF1 TIM2_CH1.
35
36	### 2. SysTick tick
37
38	```c
39	volatile uint32_t tick_ms;
40
41	void SysTick_Handler(void) {
42	tick_ms++;
43	}
44
45	void systick_init(uint32_t hz) {
46	SysTick_Config(SystemCoreClock / hz);
47	}
48	```
49
50	### 3. Input capture
51
52	Configure channel in `CCMR` as input, set `CCER` polarity, read `CCR` on interrupt when edge captured.
53
54	### 4. Agent usage
55
56	```
57	/timers-pwm-baremetal 1 kHz 25% duty PWM on TIM2 channel 1
58	```
59
60	## Common Problems
61
62	\| Symptom \| Cause \| Fix \|
63	\|---------\|-------\|-----\|
64	\| Wrong frequency \| APB timer clock doubling \| Check RM timer clock x2 rule \|
65	\| No PWM output \| CCER/CCMR not enabled \| Enable channel output \|
66	\| Jittery tick \| SysTick overridden \| One owner for SysTick \|
67
68	## Related Skills
69
70	- `skills/baremetal/gpio-baremetal` — timer pin AF
71	- `skills/embedded/freertos` — replace SysTick with RTOS tick
72	- `skills/baremetal/adc-dac-baremetal` — timer TRGO for ADC trigger

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timers-pwm-baremetal

141stars19forks

View on GitHub

How to install timers-pwm-baremetal?

mohitmishra786/low-level-dev-skills/timers-pwm-baremetal

$npx -y skills add mohitmishra786/low-level-dev-skills --skill timers-pwm-baremetal

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Timers and PWM (Bare-Metal)
2
3	## Purpose
4
5	Configure MCU timers for PWM output, input capture, and periodic scheduling: prescaler/ARR setup, compare channels, and SysTick as a simple tick source.
6
7	## When to Use
8
9	- Motor/LED dimming via PWM
10	- Measuring pulse width (input capture)
11	- Bare-metal `millis()` without FreeRTOS
12	- Hardware periodic sampling trigger
13
14	## Workflow
15
16	### 1. PWM on TIM2 CH1 (STM32)
17
18	```
19	f_pwm = f_timer_clk / ((PSC+1) * (ARR+1))
20	duty = (CCR / (ARR+1)) * 100%
21	```
22
23	```c
24	RCC->APB1ENR \|= RCC_APB1ENR_TIM2EN;
25
26	TIM2->PSC = 83; /* 84MHz / 84 = 1 MHz tick */
27	TIM2->ARR = 999; /* 1 kHz PWM */
28	TIM2->CCR1 = 500; /* 50% duty */
29	TIM2->CCMR1 \|= (6U << TIM_CCMR1_OC1M_Pos); /* PWM mode 1 */
30	TIM2->CCER \|= TIM_CCER_CC1E;
31	TIM2->CR1 \|= TIM_CR1_CEN;
32	```
33
34	GPIO: PA0 AF1 TIM2_CH1.
35
36	### 2. SysTick tick
37
38	```c
39	volatile uint32_t tick_ms;
40
41	void SysTick_Handler(void) {
42	tick_ms++;
43	}
44
45	void systick_init(uint32_t hz) {
46	SysTick_Config(SystemCoreClock / hz);
47	}
48	```
49
50	### 3. Input capture
51
52	Configure channel in `CCMR` as input, set `CCER` polarity, read `CCR` on interrupt when edge captured.
53
54	### 4. Agent usage
55
56	```
57	/timers-pwm-baremetal 1 kHz 25% duty PWM on TIM2 channel 1
58	```
59
60	## Common Problems
61
62	\| Symptom \| Cause \| Fix \|
63	\|---------\|-------\|-----\|
64	\| Wrong frequency \| APB timer clock doubling \| Check RM timer clock x2 rule \|
65	\| No PWM output \| CCER/CCMR not enabled \| Enable channel output \|
66	\| Jittery tick \| SysTick overridden \| One owner for SysTick \|
67
68	## Related Skills
69
70	- `skills/baremetal/gpio-baremetal` — timer pin AF
71	- `skills/embedded/freertos` — replace SysTick with RTOS tick
72	- `skills/baremetal/adc-dac-baremetal` — timer TRGO for ADC trigger

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6 picks

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