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machine/esp32: add PWM support using the LEDC peripheral
The classic ESP32 had no PWM. This adds it. It uses the high speed half of the LEDC peripheral. This gives 4 timers (PWM0 to PWM3) and 8 channels. You can use any pin, because the signal goes through the GPIO matrix. The ESP32-C3 and the ESP32-S3 have LEDC PWM. Most of that code is the same for all of these chips. This change uses that code again. It does not add a second driver for the same peripheral. Three functions in the shared file work only on the newer chips. They move to a file for each chip. enableClock The C3 and S3 turn on the clock in SYSTEM. This chip uses DPORT. It also has no LEDC.CONF_CLK_EN bit. setTimerConf The timer registers here are HSTIMER0_CONF. On the other chips they are TIMER0_CONF. chanOp The channel registers here are HSCH0_CONF0. On the other chips they are CH0_CONF0. The files are now: machine_esp32xx_pwm.go The shared part. It builds for esp32 also. It calls enableClock and setTimerConf. machine_esp32xx_ls_pwm.go New. It holds the two low speed functions. The code moved without a change. It builds for esp32c3 and esp32s3 only. machine_esp32_pwm.go New. The versions for the classic ESP32. Two hardware details are important. TICK_SEL has the opposite meaning on this chip. Here 1 selects APB_CLK at 80MHz and 0 selects REF_TICK at 1MHz. The low speed timers on the C3 and the S3 write 0. A 0 here makes all frequencies 80 times too slow. There is no PARA_UP bit. On the C3 and the S3 you set PARA_UP to apply a change to a channel. High speed channels apply the change themselves at the end of the period. Tests: The examples/pwm binaries for esp32c3-supermini and xiao-esp32s3 are the same byte for byte before and after this change. The move of the code did not change it. Tested on an ESP32-WROVER board. A servo on GPIO15 turns from 0 to 180 degrees and back. The movement is smooth. This shows that the timing is correct. A servo moves only with pulses between 0.5ms and 2.5ms that repeat near 50Hz. Motor control PWM (the MCPWM peripheral) is not in this change. It needs a different API.
1 parent d88abc2 commit 763c83b

5 files changed

Lines changed: 407 additions & 61 deletions

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‎make/smoketest.mk‎

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@@ -473,6 +473,8 @@ ifneq ($(XTENSA), 0)
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@$(MD5SUM) $(SMOKE_OUT).bin
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$(TINYGO) build -size short -o $(SMOKE_OUT).bin -target=esp32-coreboard-v2 examples/adc
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@$(MD5SUM) $(SMOKE_OUT).bin
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$(TINYGO) build -size short -o $(SMOKE_OUT).bin -target=esp32-coreboard-v2 examples/pwm
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@$(MD5SUM) $(SMOKE_OUT).bin
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$(TINYGO) build -size short -o $(SMOKE_OUT).bin -target=esp32c3-generic examples/machinetest
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@$(MD5SUM) $(SMOKE_OUT).bin
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$(TINYGO) build -size short -o $(SMOKE_OUT).bin -target=esp32s3-generic examples/machinetest

‎src/examples/pwm/esp32-coreboard-v2.go‎

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//go:build esp32_coreboard_v2
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package main
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import "machine"
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var (
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pwm = machine.PWM0
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pinA = machine.GPIO18
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pinB = machine.GPIO19
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)

‎src/machine/machine_esp32_pwm.go‎

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//go:build esp32
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// PWM on the classic ESP32 uses the LEDC peripheral.
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//
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// LEDC here has two halves: a high-speed one and a low-speed one. This file uses
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// the high-speed half. It gives 4 timers (PWM0-PWM3) and 8 channels.
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//
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// The code that is the same on every ESP32 chip is in machine_esp32xx_pwm.go.
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// This file adds only the parts that are different here.
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//
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// Three things are different from the ESP32-C3 and the ESP32-S3:
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//
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// - The clock is switched on in DPORT. The newer chips renamed that block to
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// SYSTEM. This chip also has no LEDC.CONF_CLK_EN bit.
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// - Register names start with HS, for example HSTIMER0_CONF and HSCH0_CONF0.
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// - There is no PARA_UP bit. On the C3 and S3 you set PARA_UP to say "apply my
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// changes now". Here the channel applies them by itself, at the end of the
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// period it is in. That is what makes it "high speed".
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// See the ESP32 TRM, chapter "LED PWM Controller".
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package machine
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import "device/esp"
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// The GPIO matrix can send an internal signal to almost any pin. Each signal has
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// a number. High-speed LEDC channel 0 is number 71, and the rest follow on from
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// there, so channels 0 to 7 are 71 to 78.
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// (From Espressif's soc/gpio_sig_map.h: LEDC_HS_SIG_OUT0_IDX.)
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const LEDC_HS_SIG_OUT0_IDX = 71
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const ledcChannelsESP32 = 8
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var (
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PWM0 = &LEDCPWM{SigOutBase: LEDC_HS_SIG_OUT0_IDX, NumChannels: ledcChannelsESP32, timerNum: 0}
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PWM1 = &LEDCPWM{SigOutBase: LEDC_HS_SIG_OUT0_IDX, NumChannels: ledcChannelsESP32, timerNum: 1}
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PWM2 = &LEDCPWM{SigOutBase: LEDC_HS_SIG_OUT0_IDX, NumChannels: ledcChannelsESP32, timerNum: 2}
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PWM3 = &LEDCPWM{SigOutBase: LEDC_HS_SIG_OUT0_IDX, NumChannels: ledcChannelsESP32, timerNum: 3}
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)
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// enableClock turns the LEDC hardware on and picks its clock.
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func (pwm *LEDCPWM) enableClock() {
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// Every peripheral starts switched off, to save power. Turn the LEDC clock
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// on, then take it out of reset. These registers are in DPORT on this chip.
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// The C3 and S3 call the same block SYSTEM.
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esp.DPORT.SetPERIP_RST_EN_LEDC_RST(1)
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esp.DPORT.SetPERIP_CLK_EN_LEDC_CLK_EN(1)
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esp.DPORT.SetPERIP_RST_EN_LEDC_RST(0)
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// Use APB_CLK, which runs at 80MHz. This chip has no CONF_CLK_EN bit, so
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// there is nothing more to switch on.
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esp.LEDC.SetCONF_APB_CLK_SEL(1)
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}
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// setTimerConf writes the resolution and the divider that Configure worked out
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// into one timer.
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//
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// Watch TICK_SEL. It is 1 here, not 0. On this chip:
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//
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// 1 = APB_CLK, 80MHz <- what we want
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// 0 = REF_TICK, 1MHz
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//
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// The low-speed timers on the C3 and S3 use the opposite meaning, so their code
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// writes 0. Writing 0 here would make every frequency 80 times too slow.
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//
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// These timers have no PARA_UP bit. The short reset pulse at the end is what
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// makes the new values take effect.
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func (pwm *LEDCPWM) setTimerConf(dutyRes uint8, divReg uint32) {
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switch pwm.timerNum {
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case 0:
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esp.LEDC.SetHSTIMER0_CONF_DUTY_RES(uint32(dutyRes))
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esp.LEDC.SetHSTIMER0_CONF_DIV_NUM(divReg)
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esp.LEDC.SetHSTIMER0_CONF_TICK_SEL(1)
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esp.LEDC.SetHSTIMER0_CONF_PAUSE(0)
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esp.LEDC.SetHSTIMER0_CONF_RST(1)
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esp.LEDC.SetHSTIMER0_CONF_RST(0)
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case 1:
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esp.LEDC.SetHSTIMER1_CONF_DUTY_RES(uint32(dutyRes))
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esp.LEDC.SetHSTIMER1_CONF_DIV_NUM(divReg)
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esp.LEDC.SetHSTIMER1_CONF_TICK_SEL(1)
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esp.LEDC.SetHSTIMER1_CONF_PAUSE(0)
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esp.LEDC.SetHSTIMER1_CONF_RST(1)
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esp.LEDC.SetHSTIMER1_CONF_RST(0)
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case 2:
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esp.LEDC.SetHSTIMER2_CONF_DUTY_RES(uint32(dutyRes))
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esp.LEDC.SetHSTIMER2_CONF_DIV_NUM(divReg)
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esp.LEDC.SetHSTIMER2_CONF_TICK_SEL(1)
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esp.LEDC.SetHSTIMER2_CONF_PAUSE(0)
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esp.LEDC.SetHSTIMER2_CONF_RST(1)
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esp.LEDC.SetHSTIMER2_CONF_RST(0)
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case 3:
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esp.LEDC.SetHSTIMER3_CONF_DUTY_RES(uint32(dutyRes))
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esp.LEDC.SetHSTIMER3_CONF_DIV_NUM(divReg)
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esp.LEDC.SetHSTIMER3_CONF_TICK_SEL(1)
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esp.LEDC.SetHSTIMER3_CONF_PAUSE(0)
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esp.LEDC.SetHSTIMER3_CONF_RST(1)
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esp.LEDC.SetHSTIMER3_CONF_RST(0)
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}
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}
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// chanOp does the work for one channel, numbered 0 to 7. It either sets the
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// channel up, changes its duty, or flips its idle level.
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//
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// Each channel has its own registers, and each register has its own generated
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// setter function. There is no array to index, so this has to be a long switch.
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// The C3 and S3 files have the same shape.
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//
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// DUTY_SCALE is set to 0. LEDC can fade slowly from one duty to the next; 0
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// turns that off, so the duty changes in a single step.
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func (pwm *LEDCPWM) chanOp(ch uint8, op ledcChanOp, duty uint32, inverting bool) {
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invVal := uint32(0)
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if inverting {
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invVal = 1
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}
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switch ch {
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case 0:
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switch op {
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case ledcChanOpInit:
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esp.LEDC.SetHSCH0_CONF0_TIMER_SEL(uint32(pwm.timerNum))
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esp.LEDC.SetHSCH0_CONF0_SIG_OUT_EN(1)
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esp.LEDC.SetHSCH0_CONF0_IDLE_LV(0)
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esp.LEDC.SetHSCH0_HPOINT_HPOINT(0)
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esp.LEDC.SetHSCH0_DUTY_DUTY(0)
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esp.LEDC.SetHSCH0_CONF1_DUTY_SCALE(0)
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esp.LEDC.SetHSCH0_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH0_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH0_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH0_CONF1_DUTY_START(1)
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case ledcChanOpSetDuty:
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esp.LEDC.SetHSCH0_DUTY_DUTY(duty)
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esp.LEDC.SetHSCH0_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH0_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH0_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH0_CONF1_DUTY_START(1)
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esp.LEDC.SetHSCH0_CONF0_SIG_OUT_EN(1)
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case ledcChanOpSetInvert:
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esp.LEDC.SetHSCH0_CONF0_IDLE_LV(invVal)
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}
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case 1:
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switch op {
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case ledcChanOpInit:
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esp.LEDC.SetHSCH1_CONF0_TIMER_SEL(uint32(pwm.timerNum))
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esp.LEDC.SetHSCH1_CONF0_SIG_OUT_EN(1)
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esp.LEDC.SetHSCH1_CONF0_IDLE_LV(0)
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esp.LEDC.SetHSCH1_HPOINT_HPOINT(0)
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esp.LEDC.SetHSCH1_DUTY_DUTY(0)
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esp.LEDC.SetHSCH1_CONF1_DUTY_SCALE(0)
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esp.LEDC.SetHSCH1_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH1_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH1_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH1_CONF1_DUTY_START(1)
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case ledcChanOpSetDuty:
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esp.LEDC.SetHSCH1_DUTY_DUTY(duty)
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esp.LEDC.SetHSCH1_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH1_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH1_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH1_CONF1_DUTY_START(1)
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esp.LEDC.SetHSCH1_CONF0_SIG_OUT_EN(1)
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case ledcChanOpSetInvert:
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esp.LEDC.SetHSCH1_CONF0_IDLE_LV(invVal)
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}
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case 2:
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switch op {
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case ledcChanOpInit:
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esp.LEDC.SetHSCH2_CONF0_TIMER_SEL(uint32(pwm.timerNum))
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esp.LEDC.SetHSCH2_CONF0_SIG_OUT_EN(1)
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esp.LEDC.SetHSCH2_CONF0_IDLE_LV(0)
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esp.LEDC.SetHSCH2_HPOINT_HPOINT(0)
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esp.LEDC.SetHSCH2_DUTY_DUTY(0)
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esp.LEDC.SetHSCH2_CONF1_DUTY_SCALE(0)
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esp.LEDC.SetHSCH2_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH2_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH2_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH2_CONF1_DUTY_START(1)
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case ledcChanOpSetDuty:
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esp.LEDC.SetHSCH2_DUTY_DUTY(duty)
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esp.LEDC.SetHSCH2_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH2_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH2_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH2_CONF1_DUTY_START(1)
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esp.LEDC.SetHSCH2_CONF0_SIG_OUT_EN(1)
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case ledcChanOpSetInvert:
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esp.LEDC.SetHSCH2_CONF0_IDLE_LV(invVal)
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}
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case 3:
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switch op {
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case ledcChanOpInit:
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esp.LEDC.SetHSCH3_CONF0_TIMER_SEL(uint32(pwm.timerNum))
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esp.LEDC.SetHSCH3_CONF0_SIG_OUT_EN(1)
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esp.LEDC.SetHSCH3_CONF0_IDLE_LV(0)
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esp.LEDC.SetHSCH3_HPOINT_HPOINT(0)
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esp.LEDC.SetHSCH3_DUTY_DUTY(0)
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esp.LEDC.SetHSCH3_CONF1_DUTY_SCALE(0)
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esp.LEDC.SetHSCH3_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH3_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH3_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH3_CONF1_DUTY_START(1)
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case ledcChanOpSetDuty:
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esp.LEDC.SetHSCH3_DUTY_DUTY(duty)
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esp.LEDC.SetHSCH3_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH3_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH3_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH3_CONF1_DUTY_START(1)
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esp.LEDC.SetHSCH3_CONF0_SIG_OUT_EN(1)
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case ledcChanOpSetInvert:
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esp.LEDC.SetHSCH3_CONF0_IDLE_LV(invVal)
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}
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case 4:
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switch op {
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case ledcChanOpInit:
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esp.LEDC.SetHSCH4_CONF0_TIMER_SEL(uint32(pwm.timerNum))
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esp.LEDC.SetHSCH4_CONF0_SIG_OUT_EN(1)
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esp.LEDC.SetHSCH4_CONF0_IDLE_LV(0)
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esp.LEDC.SetHSCH4_HPOINT_HPOINT(0)
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esp.LEDC.SetHSCH4_DUTY_DUTY(0)
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esp.LEDC.SetHSCH4_CONF1_DUTY_SCALE(0)
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esp.LEDC.SetHSCH4_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH4_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH4_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH4_CONF1_DUTY_START(1)
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case ledcChanOpSetDuty:
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esp.LEDC.SetHSCH4_DUTY_DUTY(duty)
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esp.LEDC.SetHSCH4_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH4_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH4_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH4_CONF1_DUTY_START(1)
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esp.LEDC.SetHSCH4_CONF0_SIG_OUT_EN(1)
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case ledcChanOpSetInvert:
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esp.LEDC.SetHSCH4_CONF0_IDLE_LV(invVal)
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}
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case 5:
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switch op {
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case ledcChanOpInit:
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esp.LEDC.SetHSCH5_CONF0_TIMER_SEL(uint32(pwm.timerNum))
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esp.LEDC.SetHSCH5_CONF0_SIG_OUT_EN(1)
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esp.LEDC.SetHSCH5_CONF0_IDLE_LV(0)
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esp.LEDC.SetHSCH5_HPOINT_HPOINT(0)
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esp.LEDC.SetHSCH5_DUTY_DUTY(0)
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esp.LEDC.SetHSCH5_CONF1_DUTY_SCALE(0)
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esp.LEDC.SetHSCH5_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH5_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH5_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH5_CONF1_DUTY_START(1)
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case ledcChanOpSetDuty:
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esp.LEDC.SetHSCH5_DUTY_DUTY(duty)
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esp.LEDC.SetHSCH5_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH5_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH5_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH5_CONF1_DUTY_START(1)
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esp.LEDC.SetHSCH5_CONF0_SIG_OUT_EN(1)
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case ledcChanOpSetInvert:
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esp.LEDC.SetHSCH5_CONF0_IDLE_LV(invVal)
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}
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case 6:
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switch op {
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case ledcChanOpInit:
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esp.LEDC.SetHSCH6_CONF0_TIMER_SEL(uint32(pwm.timerNum))
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esp.LEDC.SetHSCH6_CONF0_SIG_OUT_EN(1)
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esp.LEDC.SetHSCH6_CONF0_IDLE_LV(0)
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esp.LEDC.SetHSCH6_HPOINT_HPOINT(0)
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esp.LEDC.SetHSCH6_DUTY_DUTY(0)
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esp.LEDC.SetHSCH6_CONF1_DUTY_SCALE(0)
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esp.LEDC.SetHSCH6_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH6_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH6_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH6_CONF1_DUTY_START(1)
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case ledcChanOpSetDuty:
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esp.LEDC.SetHSCH6_DUTY_DUTY(duty)
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esp.LEDC.SetHSCH6_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH6_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH6_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH6_CONF1_DUTY_START(1)
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esp.LEDC.SetHSCH6_CONF0_SIG_OUT_EN(1)
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case ledcChanOpSetInvert:
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esp.LEDC.SetHSCH6_CONF0_IDLE_LV(invVal)
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}
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case 7:
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switch op {
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case ledcChanOpInit:
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esp.LEDC.SetHSCH7_CONF0_TIMER_SEL(uint32(pwm.timerNum))
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esp.LEDC.SetHSCH7_CONF0_SIG_OUT_EN(1)
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esp.LEDC.SetHSCH7_CONF0_IDLE_LV(0)
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esp.LEDC.SetHSCH7_HPOINT_HPOINT(0)
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esp.LEDC.SetHSCH7_DUTY_DUTY(0)
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esp.LEDC.SetHSCH7_CONF1_DUTY_SCALE(0)
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esp.LEDC.SetHSCH7_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH7_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH7_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH7_CONF1_DUTY_START(1)
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case ledcChanOpSetDuty:
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esp.LEDC.SetHSCH7_DUTY_DUTY(duty)
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esp.LEDC.SetHSCH7_CONF1_DUTY_CYCLE(1)
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esp.LEDC.SetHSCH7_CONF1_DUTY_NUM(1)
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esp.LEDC.SetHSCH7_CONF1_DUTY_INC(1)
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esp.LEDC.SetHSCH7_CONF1_DUTY_START(1)
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esp.LEDC.SetHSCH7_CONF0_SIG_OUT_EN(1)
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case ledcChanOpSetInvert:
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esp.LEDC.SetHSCH7_CONF0_IDLE_LV(invVal)
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}
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}
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}

‎src/machine/machine_esp32xx_ls_pwm.go‎

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//go:build esp32c3 || esp32s3
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// Low-speed LEDC code, shared by the ESP32-C3 and the ESP32-S3.
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//
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// Both chips have only the low-speed LEDC block. Their clock and timer registers
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// use the same names, so one copy of this code serves both.
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//
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// The classic ESP32 has a high-speed block instead, with different register
9+
// names. Its versions of these two functions are in machine_esp32_pwm.go.
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//
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// The SVD (lib/cmsis-svd/data/Espressif/esp32s3.svd) describes the two bits that
12+
// make a change take effect on these chips. CONF0.PARA_UP "updates HPOINT,
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// DUTY_START, SIG_OUT_EN, TIMER_SEL, DUTY_NUM, DUTY_CYCLE, DUTY_SCALE, DUTY_INC
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// for channel and is auto-cleared by hardware". CONF1.DUTY_START "other CONF1
15+
// fields take effect when this bit is set to 1".
16+
17+
package machine
18+
19+
import "device/esp"
20+
21+
// enableClock turns the LEDC hardware on and picks APB_CLK as its clock.
22+
func (pwm *LEDCPWM) enableClock() {
23+
// Enable LEDC clock and release reset (SYSTEM perip_clk_en0 / perip_rst_en0).
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esp.SYSTEM.SetPERIP_RST_EN0_LEDC_RST(1)
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esp.SYSTEM.SetPERIP_CLK_EN0_LEDC_CLK_EN(1)
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esp.SYSTEM.SetPERIP_RST_EN0_LEDC_RST(0)
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// LEDC global: APB clock source, enable internal clock.
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esp.LEDC.SetCONF_APB_CLK_SEL(1)
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esp.LEDC.SetCONF_CLK_EN(1)
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}
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func (pwm *LEDCPWM) setTimerConf(dutyRes uint8, divReg uint32) {
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t := pwm.timerNum
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switch t {
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case 0:
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esp.LEDC.SetTIMER0_CONF_DUTY_RES(uint32(dutyRes))
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esp.LEDC.SetTIMER0_CONF_CLK_DIV(divReg)
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esp.LEDC.SetTIMER0_CONF_TICK_SEL(0)
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esp.LEDC.SetTIMER0_CONF_PAUSE(0)
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esp.LEDC.SetTIMER0_CONF_RST(1)
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esp.LEDC.SetTIMER0_CONF_RST(0)
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esp.LEDC.SetTIMER0_CONF_PARA_UP(1)
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case 1:
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esp.LEDC.SetTIMER1_CONF_DUTY_RES(uint32(dutyRes))
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esp.LEDC.SetTIMER1_CONF_CLK_DIV(divReg)
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esp.LEDC.SetTIMER1_CONF_TICK_SEL(0)
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esp.LEDC.SetTIMER1_CONF_PAUSE(0)
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esp.LEDC.SetTIMER1_CONF_RST(1)
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esp.LEDC.SetTIMER1_CONF_RST(0)
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esp.LEDC.SetTIMER1_CONF_PARA_UP(1)
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case 2:
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esp.LEDC.SetTIMER2_CONF_DUTY_RES(uint32(dutyRes))
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esp.LEDC.SetTIMER2_CONF_CLK_DIV(divReg)
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esp.LEDC.SetTIMER2_CONF_TICK_SEL(0)
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esp.LEDC.SetTIMER2_CONF_PAUSE(0)
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esp.LEDC.SetTIMER2_CONF_RST(1)
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esp.LEDC.SetTIMER2_CONF_RST(0)
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esp.LEDC.SetTIMER2_CONF_PARA_UP(1)
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case 3:
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esp.LEDC.SetTIMER3_CONF_DUTY_RES(uint32(dutyRes))
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esp.LEDC.SetTIMER3_CONF_CLK_DIV(divReg)
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esp.LEDC.SetTIMER3_CONF_TICK_SEL(0)
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esp.LEDC.SetTIMER3_CONF_PAUSE(0)
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esp.LEDC.SetTIMER3_CONF_RST(1)
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esp.LEDC.SetTIMER3_CONF_RST(0)
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esp.LEDC.SetTIMER3_CONF_PARA_UP(1)
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}
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}

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