IOCTL_PWM_CONTROLLER_SET_DESIRED_PERIOD IOCTL (pwm.h)

Article
10/21/2021

Sets the output signal period of a Pulse Width Modulation (PWM) controller to a suggested value.

Input buffer

A pointer to a buffer that contains a PWM_CONTROLLER_SET_DESIRED_PERIOD_INPUT struct. The associated value is the requested output signal period, in picoseconds, for the controller. This value must be greater than zero (0). It must be in the controller supported range of periods, which is between the MinimumPeriod and MaximumPeriod values, inclusive, which you can obtain by using IOCTL_PWM_CONTROLLER_GET_INFO.

Input buffer length

The size of the input buffer, in bytes.

Output buffer

A pointer to a buffer that contains a PWM_CONTROLLER_SET_DESIRED_PERIOD_INPUT struct. The associated value is the effective output signal period of the Pulse Width Modulation (PWM) controller. It can later be retrieved by using IOCTL_PWM_CONTROLLER_GET_ACTUAL_PERIOD.

Output buffer length

The size of the output buffer, in bytes.

Remarks

To perform this operation, call the DeviceIoControl function with the following parameters.

BOOL 
   WINAPI 
   DeviceIoControl( (HANDLE)       hDevice,         // handle to device
                    (DWORD)        IOCTL_PWM_CONTROLLER_SET_DESIRED_PERIOD, // dwIoControlCode(LPDWORD)      lpInBuffer,      // input buffer
                    (DWORD)        nInBufferSize,   // size of input buffer
                    (LPDWORD)      lpOutBuffer,     // output buffer
                    (DWORD)        nOutBufferSize,  // size of output buffer
                    (LPDWORD)      lpBytesReturned, // number of bytes returned
                    (LPOVERLAPPED) lpOverlapped );  // OVERLAPPED structure

Parameters	Description
hDevice [in]	A handle to the device. To obtain a device handle, call the CreateFile function.
dwIoControlCode [in]	The control code for the operation. Use IOCTL_PWM_CONTROLLER_SET_DESIRED_PERIOD for this operation.
lpInBuffer	A pointer to a buffer that contains a PWM_CONTROLLER_SET_DESIRED_PERIOD_INPUT struct. The associated value is the requested output signal period, in picoseconds, for the controller. This value must be greater than zero (0). It must be in the controller supported range of periods, which is between the MinimumPeriod and MaximumPeriod values, inclusive, which you can obtain by using IOCTL_PWM_CONTROLLER_GET_INFO.
nInBufferSize [in]	The size of the input buffer, in bytes.
lpOutBuffer [out]	A pointer to a buffer that contains a PWM_CONTROLLER_SET_DESIRED_PERIOD_INPUT struct. The associated value is the effective output signal period of the Pulse Width Modulation (PWM) controller. It can later be retrieved by using IOCTL_PWM_CONTROLLER_GET_ACTUAL_PERIOD.
nOutBufferSize [in]	The size of the output buffer, in bytes.
lpBytesReturned [out]	LPDWORD A pointer to a variable that receives the size of the data stored in the output buffer, in bytes. If the output buffer is too small, the call fails, GetLastError returns ERROR_INSUFFICIENT_BUFFER, and lpBytesReturned is zero. If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl makes use of lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless. If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If the hDevice parameter is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.
lpOverlapped [in]	LPOVERLAPPED A pointer to an OVERLAPPED structure. If hDevice was opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored. If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped (asynchronous) operation. In this case, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways. For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed. Otherwise, the function does not return until the operation has been completed or an error occurs.

Requirements

Requirement	Value
Minimum supported client	Windows 10 [desktop apps only]
Minimum supported server	Windows Server 2016 [desktop apps only]
Header	pwm.h (include Pwm.h)

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