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-rw-r--r--docs/esp32/tutorial/pwm.rst220
1 files changed, 178 insertions, 42 deletions
diff --git a/docs/esp32/tutorial/pwm.rst b/docs/esp32/tutorial/pwm.rst
index 2650284d35..82d43b36f6 100644
--- a/docs/esp32/tutorial/pwm.rst
+++ b/docs/esp32/tutorial/pwm.rst
@@ -11,16 +11,20 @@ compared with the length of a single period (low plus high time). Maximum
duty cycle is when the pin is high all of the time, and minimum is when it is
low all of the time.
-* More comprehensive example with all 16 PWM channels and 8 timers::
+* More comprehensive example with all **16 PWM channels and 8 timers**::
+ from time import sleep
from machine import Pin, PWM
try:
- f = 100 # Hz
- d = 1024 // 16 # 6.25%
- pins = (15, 2, 4, 16, 18, 19, 22, 23, 25, 26, 27, 14 , 12, 13, 32, 33)
+ F = 10000 # Hz
+ D = 65536 // 16 # 6.25%
+ pins = (2, 4, 12, 13, 14, 15, 16, 18, 19, 22, 23, 25, 26, 27, 32, 33)
pwms = []
for i, pin in enumerate(pins):
- pwms.append(PWM(Pin(pin), freq=f * (i // 2 + 1), duty= 1023 if i==15 else d * (i + 1)))
+ f = F * (i // 2 + 1)
+ d = min(65535, D * (i + 1))
+ pwms.append(PWM(pin, freq=f, duty_u16=d))
+ sleep(2 / f)
print(pwms[i])
finally:
for pwm in pwms:
@@ -31,65 +35,100 @@ low all of the time.
Output is::
- PWM(Pin(15), freq=100, duty=64, resolution=10, mode=0, channel=0, timer=0)
- PWM(Pin(2), freq=100, duty=128, resolution=10, mode=0, channel=1, timer=0)
- PWM(Pin(4), freq=200, duty=192, resolution=10, mode=0, channel=2, timer=1)
- PWM(Pin(16), freq=200, duty=256, resolution=10, mode=0, channel=3, timer=1)
- PWM(Pin(18), freq=300, duty=320, resolution=10, mode=0, channel=4, timer=2)
- PWM(Pin(19), freq=300, duty=384, resolution=10, mode=0, channel=5, timer=2)
- PWM(Pin(22), freq=400, duty=448, resolution=10, mode=0, channel=6, timer=3)
- PWM(Pin(23), freq=400, duty=512, resolution=10, mode=0, channel=7, timer=3)
- PWM(Pin(25), freq=500, duty=576, resolution=10, mode=1, channel=0, timer=0)
- PWM(Pin(26), freq=500, duty=640, resolution=10, mode=1, channel=1, timer=0)
- PWM(Pin(27), freq=600, duty=704, resolution=10, mode=1, channel=2, timer=1)
- PWM(Pin(14), freq=600, duty=768, resolution=10, mode=1, channel=3, timer=1)
- PWM(Pin(12), freq=700, duty=832, resolution=10, mode=1, channel=4, timer=2)
- PWM(Pin(13), freq=700, duty=896, resolution=10, mode=1, channel=5, timer=2)
- PWM(Pin(32), freq=800, duty=960, resolution=10, mode=1, channel=6, timer=3)
- PWM(Pin(33), freq=800, duty=1023, resolution=10, mode=1, channel=7, timer=3)
-
-* Example of a smooth frequency change::
+ PWM(Pin(2), freq=10000, duty_u16=4096)
+ PWM(Pin(4), freq=10000, duty_u16=8192)
+ PWM(Pin(12), freq=20000, duty_u16=12288)
+ PWM(Pin(13), freq=20000, duty_u16=16384)
+ PWM(Pin(14), freq=30030, duty_u16=20480)
+ PWM(Pin(15), freq=30030, duty_u16=24576)
+ PWM(Pin(16), freq=40000, duty_u16=28672)
+ PWM(Pin(18), freq=40000, duty_u16=32768)
+ PWM(Pin(19), freq=50000, duty_u16=36864)
+ PWM(Pin(22), freq=50000, duty_u16=40960)
+ PWM(Pin(23), freq=60060, duty_u16=45056)
+ PWM(Pin(25), freq=60060, duty_u16=49152)
+ PWM(Pin(26), freq=69930, duty_u16=53248)
+ PWM(Pin(27), freq=69930, duty_u16=57344)
+ PWM(Pin(32), freq=80000, duty_u16=61440)
+ PWM(Pin(33), freq=80000, duty_u16=65535)
+
+
+* Example of a **smooth frequency change**::
from time import sleep
from machine import Pin, PWM
- F_MIN = 500
- F_MAX = 1000
+ F_MIN = 1000
+ F_MAX = 10000
f = F_MIN
- delta_f = 1
+ delta_f = F_MAX // 50
- p = PWM(Pin(5), f)
- print(p)
+ pwm = PWM(Pin(27), f)
while True:
- p.freq(f)
-
- sleep(10 / F_MIN)
+ pwm.freq(f)
+ sleep(1 / f)
+ sleep(0.1)
+ print(pwm)
f += delta_f
- if f >= F_MAX or f <= F_MIN:
+ if f > F_MAX or f < F_MIN:
delta_f = -delta_f
+ print()
+ if f > F_MAX:
+ f = F_MAX
+ elif f < F_MIN:
+ f = F_MIN
- See PWM wave at Pin(5) with an oscilloscope.
+ See PWM wave on Pin(27) with an oscilloscope.
+
+ Output is::
-* Example of a smooth duty change::
+ PWM(Pin(27), freq=998, duty_u16=32768)
+ PWM(Pin(27), freq=1202, duty_u16=32768)
+ PWM(Pin(27), freq=1401, duty_u16=32768)
+ PWM(Pin(27), freq=1598, duty_u16=32768)
+ ...
+ PWM(Pin(27), freq=9398, duty_u16=32768)
+ PWM(Pin(27), freq=9615, duty_u16=32768)
+ PWM(Pin(27), freq=9804, duty_u16=32768)
+ PWM(Pin(27), freq=10000, duty_u16=32768)
+
+ PWM(Pin(27), freq=10000, duty_u16=32768)
+ PWM(Pin(27), freq=9804, duty_u16=32768)
+ PWM(Pin(27), freq=9615, duty_u16=32768)
+ PWM(Pin(27), freq=9398, duty_u16=32768)
+ ...
+ PWM(Pin(27), freq=1598, duty_u16=32768)
+ PWM(Pin(27), freq=1401, duty_u16=32768)
+ PWM(Pin(27), freq=1202, duty_u16=32768)
+ PWM(Pin(27), freq=998, duty_u16=32768)
+
+
+* Example of a **smooth duty change**::
from time import sleep
from machine import Pin, PWM
- DUTY_MAX = 2**16 - 1
+ DUTY_MAX = 65535
duty_u16 = 0
- delta_d = 16
+ delta_d = 256
- p = PWM(Pin(5), 1000, duty_u16=duty_u16)
- print(p)
+ pwm = PWM(Pin(27), freq=1000, duty_u16=duty_u16)
while True:
- p.duty_u16(duty_u16)
+ pwm.duty_u16(duty_u16)
+ sleep(2 / pwm.freq())
+ print(pwm)
- sleep(1 / 1000)
+ if duty_u16 >= DUTY_MAX:
+ print()
+ sleep(2)
+ elif duty_u16 <= 0:
+ print()
+ sleep(2)
duty_u16 += delta_d
if duty_u16 >= DUTY_MAX:
@@ -99,9 +138,106 @@ low all of the time.
duty_u16 = 0
delta_d = -delta_d
- See PWM wave at Pin(5) with an oscilloscope.
+ PWM wave on Pin(27) with an oscilloscope.
+
+ Output is::
+
+ PWM(Pin(27), freq=998, duty_u16=0)
+ PWM(Pin(27), freq=998, duty_u16=256)
+ PWM(Pin(27), freq=998, duty_u16=512)
+ PWM(Pin(27), freq=998, duty_u16=768)
+ PWM(Pin(27), freq=998, duty_u16=1024)
+ ...
+ PWM(Pin(27), freq=998, duty_u16=64512)
+ PWM(Pin(27), freq=998, duty_u16=64768)
+ PWM(Pin(27), freq=998, duty_u16=65024)
+ PWM(Pin(27), freq=998, duty_u16=65280)
+ PWM(Pin(27), freq=998, duty_u16=65535)
+
+ PWM(Pin(27), freq=998, duty_u16=65279)
+ PWM(Pin(27), freq=998, duty_u16=65023)
+ PWM(Pin(27), freq=998, duty_u16=64767)
+ PWM(Pin(27), freq=998, duty_u16=64511)
+ ...
+ PWM(Pin(27), freq=998, duty_u16=1023)
+ PWM(Pin(27), freq=998, duty_u16=767)
+ PWM(Pin(27), freq=998, duty_u16=511)
+ PWM(Pin(27), freq=998, duty_u16=255)
+ PWM(Pin(27), freq=998, duty_u16=0)
+
+
+* Example of a **smooth duty change and PWM output inversion**::
+
+ from utime import sleep
+ from machine import Pin, PWM
+
+ try:
+ DUTY_MAX = 65535
+
+ duty_u16 = 0
+ delta_d = 65536 // 32
+
+ pwm = PWM(Pin(27))
+ pwmi = PWM(Pin(32), invert=1)
+
+ while True:
+ pwm.duty_u16(duty_u16)
+ pwmi.duty_u16(duty_u16)
+
+ duty_u16 += delta_d
+ if duty_u16 >= DUTY_MAX:
+ duty_u16 = DUTY_MAX
+ delta_d = -delta_d
+ elif duty_u16 <= 0:
+ duty_u16 = 0
+ delta_d = -delta_d
+
+ sleep(.01)
+ print(pwm)
+ print(pwmi)
+
+ finally:
+ try:
+ pwm.deinit()
+ except:
+ pass
+ try:
+ pwmi.deinit()
+ except:
+ pass
+
+ Output is::
+
+ PWM(Pin(27), freq=5000, duty_u16=0)
+ PWM(Pin(32), freq=5000, duty_u16=32768, invert=1)
+ PWM(Pin(27), freq=5000, duty_u16=2048)
+ PWM(Pin(32), freq=5000, duty_u16=2048, invert=1)
+ PWM(Pin(27), freq=5000, duty_u16=4096)
+ PWM(Pin(32), freq=5000, duty_u16=4096, invert=1)
+ PWM(Pin(27), freq=5000, duty_u16=6144)
+ PWM(Pin(32), freq=5000, duty_u16=6144, invert=1)
+ PWM(Pin(27), freq=5000, duty_u16=8192)
+ PWM(Pin(32), freq=5000, duty_u16=8192, invert=1)
+ ...
+
+
+ See PWM waves on Pin(27) and Pin(32) with an oscilloscope.
+
+Note: New PWM parameters take effect in the next PWM cycle.
+
+ pwm = PWM(2, duty=512)
+ print(pwm)
+ >>> PWM(Pin(2), freq=5000, duty=1023) # the duty is not relevant
+ pwm.init(freq=2, duty=64)
+ print(pwm)
+ >>> PWM(Pin(2), freq=2, duty=16) # the duty is not relevant
+ time.sleep(1 / 2) # wait one PWM period
+ print(pwm)
+ >>> PWM(Pin(2), freq=2, duty=64) # the duty is actual
+
+Note: machine.freq(20_000_000) reduces the highest PWM frequency to 10 MHz.
-Note: the Pin.OUT mode does not need to be specified. The channel is initialized
+Note: the Pin.OUT mode does not need to be specified. The channel is initialized
to PWM mode internally once for each Pin that is passed to the PWM constructor.
The following code is wrong::
generated by cgit v1.2.3 (git 2.39.1) at 2025-05-29 00:54:21 +0000