pwm pins exhibit bimodal behavior

[pcduino]

pwm pins exhibit bimodal behavior

[mwhooker]

Here's dmesg from a run of the breaking script

   1 [  268.944775] sb-pwm: pwm_disable 1
   2 [  268.944817] sb-pwm: set_pwm_gpio_level ret=0
   3 [  268.945281] sb-pwm: pwm_config duty=7, period=2000
   4 [  268.945292] sb-pwm: pwm_config 1
   5 [  268.945302] sb-pwm: pre_scal:120, entire_cycle:256, pwm_freq:781
   6 [  268.945310] sb-pwm: ----781
   7 [  268.945317] sb-pwm: pre_scal:180, entire_cycle:256, pwm_freq:520
   8 [  268.945325] sb-pwm: ----520
   9 [  268.945332] sb-pwm: pre_scal_id=1, active_cycle=1
  10 [  268.945341] sb-pwm: pwm_enable 1
  11 [  268.945745] sb-pwm: pwm_config duty=15, period=2000
  12 [  268.945755] sb-pwm: pwm_config 1
  13 [  268.945764] sb-pwm: pre_scal:120, entire_cycle:256, pwm_freq:781
  14 [  268.945772] sb-pwm: ----781
  15 [  268.945779] sb-pwm: pre_scal:180, entire_cycle:256, pwm_freq:520
  16 [  268.945787] sb-pwm: ----520
  17 [  268.945794] sb-pwm: pre_scal_id=1, active_cycle=2
  18 [  268.945802] sb-pwm: pwm_enable 1
  19 [  268.946193] sb-pwm: pwm_disable 1
  20 [  268.946213] sb-pwm: set_pwm_gpio_level ret=0
  21 [  268.957074] sb-pwm: pwm_config duty=7, period=2000
  22 [  268.957089] sb-pwm: pwm_config 1
  23 [  268.957098] sb-pwm: pre_scal:120, entire_cycle:256, pwm_freq:781
  24 [  268.957106] sb-pwm: ----781
  25 [  268.957113] sb-pwm: pre_scal:180, entire_cycle:256, pwm_freq:520
  26 [  268.957121] sb-pwm: ----520
  27 [  268.957128] sb-pwm: pre_scal_id=1, active_cycle=1
  28 [  268.957137] sb-pwm: pwm_enable 1
  29 [  268.967971] sb-pwm: pwm_config duty=15, period=2000
  30 [  268.967985] sb-pwm: pwm_config 1
  31 [  268.967994] sb-pwm: pre_scal:120, entire_cycle:256, pwm_freq:781
  32 [  268.968002] sb-pwm: ----781
  33 [  268.968009] sb-pwm: pre_scal:180, entire_cycle:256, pwm_freq:520
  34 [  268.968017] sb-pwm: ----520
  35 [  268.968025] sb-pwm: pre_scal_id=1, active_cycle=2
  36 [  268.968033] sb-pwm: pwm_enable 1
  37 [  268.978778] sb-pwm: pwm_config duty=23, period=2000
  38 [  268.978792] sb-pwm: pwm_config 1
  39 [  268.978802] sb-pwm: pre_scal:120, entire_cycle:256, pwm_freq:781
  40 [  268.978810] sb-pwm: ----781
  41 [  268.978817] sb-pwm: pre_scal:180, entire_cycle:256, pwm_freq:520
  42 [  268.978826] sb-pwm: ----520
  43 [  268.978833] sb-pwm: pre_scal_id=1, active_cycle=3
  44 [  268.978841] sb-pwm: pwm_enable 1
  45 [  268.989513] sb-pwm: pwm_config duty=31, period=2000
  46 [  268.989525] sb-pwm: pwm_config 1
  47 [  268.989534] sb-pwm: pre_scal:120, entire_cycle:256, pwm_freq:781
  48 [  268.989542] sb-pwm: ----781
  49 [  268.989549] sb-pwm: pre_scal:180, entire_cycle:256, pwm_freq:520
  50 [  268.989557] sb-pwm: ----520

and the actual script

import time
from pcduino import pwm

if __name__ == '__main__':
    pin = 2
    for i in xrange(3):
        pwm.analog_write(pin, i)

    for i in xrange(4):
        pwm.analog_write(pin, i)
        time.sleep(0.01)
    pwm.analog_write(pin, 0)

[mwhooker]

This script will reliably reproduce the issue

from pcduino import pwm

if __name__ == '__main__':

    for i in xrange(256):
        pwm.analog_write(1, i)

I can also reproduce the issue in bash

for i in $(seq 0 255); do
    echo -n $i > /sys/class/leds/pwm1/brightness;
done

The upper binary value seems to be the second value written in rapid succession. i.e. the upper value in this example appeared to be "1".

[mwhooker]

Just pinged @linksprite. Will report back.

[mwhooker]

Heard from the developers that this issue should be fixed in the latest pcduino image.

[labixiaohu]

The following error occurred while I was editing my project: No such file or directory :/sys/class/misc/pwmtimer/enable