diff options
Diffstat (limited to 'hsm-pwm/Hsm/PWM.hs')
| -rw-r--r-- | hsm-pwm/Hsm/PWM.hs | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/hsm-pwm/Hsm/PWM.hs b/hsm-pwm/Hsm/PWM.hs index ad4c052..6b2a882 100644 --- a/hsm-pwm/Hsm/PWM.hs +++ b/hsm-pwm/Hsm/PWM.hs @@ -3,7 +3,7 @@ module Hsm.PWM ( PWMHandle , PWMChannel(PWM2, PWM3) - , setFrequency + , setCycleDuration , allocatePWM ) where @@ -78,16 +78,23 @@ setDutyCycle channel dutyCycle = do where (_, _, dutyCyclePath) = channelPaths channel -setFrequency :: PWMHandle -> PWMChannel -> Int -> IO () -setFrequency _ channel frequency = do +setCycleDuration :: PWMHandle -> PWMChannel -> Int -> IO () +setCycleDuration _ channel 0 = do + logMsg $ "Halting PWM signals on channel " <> pack (show channel) + setEnable channel False +setCycleDuration _ channel cycleDuration = do logMsg - $ "Setting frequency on channel " + $ "Setting cycle duration on channel " <> pack (show channel) <> " to " - <> pack (show frequency) + <> pack (show cycleDuration) setEnable channel False - setPeriod channel frequency - setDutyCycle channel $ frequency `div` 2 + -- Sets the duty cycle to zero before updating the period. This prevents + -- `Invalid argument` errors, as the period must never be set to a value + -- smaller than the duty cycle. + setDutyCycle channel 0 + setPeriod channel cycleDuration + setDutyCycle channel $ cycleDuration `div` 2 setEnable channel True allocatePWM :: Region -> (PWMChannel -> Int) -> IO PWMHandle @@ -118,7 +125,7 @@ allocatePWM region mapper = alloc_ region acquire $ const release waitWritable enablePath waitWritable periodPath waitWritable dutyCyclePath - setFrequency PWMHandle channel $ mapper channel + setCycleDuration PWMHandle channel $ mapper channel acquire = do waitWritable exportPath waitWritable unexportPath |